The invention relates to a method for configuring subframes for uplink/downlink communication for a mobile station (UE) not supporting dual uplink but located in a communication system supporting dual connectivity. The UE is connected simultaneously to two base stations via a respective communication link. An uplink transmission pattern is determined, defining whether subframes are usable for uplink communication to the first or second base station or for switching the uplink communication between the two communication links. Based on the determined uplink transmission pattern, and further based on configuration of the mobile station for supporting dual reception or not, a downlink reception is derived for downlink communication between the two base stations and the mobile station, the downlink reception pattern defining whether the subframes are usable for downlink communication from the first or second base station or for switching the downlink communication between the two communication links.

Long Term Evolution (LTE)
Third-generation mobile systems (3G) based on WCDMA radio-access technology are being deployed on a broad scale all around the world. A first step in enhancing or evolving this technology entails introducing High-Speed Downlink Packet Access (HSDPA) and an enhanced uplink, also referred to as High Speed Uplink Packet Access (HSUPA), giving a radio access technology that is highly competitive.
In order to be prepared for further increasing user demands and to be competitive against new radio access technologies, 3GPP introduced a new mobile communication system which is called Long Term Evolution (LTE). LTE is designed to meet the carrier needs for high speed data and media transport as well as high capacity voice support for the next decade. The ability to provide high bit rates is a key measure for LTE.
The work item (WI) specification on Long-Term Evolution (LTE) called Evolved UMTS Terrestrial Radio Access (UTRA) and UMTS Terrestrial Radio Access Network (UTRAN) is finalized as Release 8 (LTE Rel. 8). The LTE system represents efficient packet-based radio access and radio access networks that provide full IP-based functionalities with low latency and low cost. In LTE, scalable multiple transmission bandwidths are specified such as 1.4, 3.0, 5.0, 10.0, 15.0, and 20.0 MHz, in order to achieve flexible system deployment using a given spectrum. In the downlink, Orthogonal Frequency Division Multiplexing (OFDM) based radio access was adopted because of its inherent immunity to multipath interference (MPI) due to a low symbol rate, the use of a cyclic prefix (CP) and its affinity to different transmission bandwidth arrangements. Single-carrier frequency division multiple access (SC-FDMA) based radio access was adopted in the uplink, since provisioning of wide area coverage was prioritized over improvement in the peak data rate considering the restricted transmit power of the user equipment (UE). Many key packet radio access techniques are employed including multiple-input multiple-output (MIMO) channel transmission techniques and a highly efficient control signaling structure is achieved in LTE Rel. 8/9.
LTE Architecture
The overall architecture is shown in FIG. 1 and a more detailed representation of the E-UTRAN architecture is given in FIG. 2. The E-UTRAN consists of an eNodeB, providing the E-UTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the user equipment (UE). The eNodeB (eNB) hosts the Physical (PHY), Medium Access Control (MAC), Radio Link Control (RLC) and Packet Data Control Protocol (PDCP) layers that include the functionality of user-plane header-compression and encryption. It also offers Radio Resource Control (RRC) functionality corresponding to the control plane. It performs many functions including radio resource management, admission control, scheduling, enforcement of negotiated uplink Quality of Service (QoS), cell information broadcast, ciphering/deciphering of user and control plane data, and compression/decompression of downlink/uplink user plane packet headers. The eNodeBs are interconnected with each other by means of the X2 interface.
The eNodeBs are also connected by means of the S1 interface to the EPC (Evolved Packet Core), more specifically to the MME (Mobility Management Entity) by means of the S1-MME and to the Serving Gateway (SGW) by means of the S1-U. The S1 interface supports a many-to-many relation between MMEs/Serving Gateways and eNodeBs. The SGW routes and forwards user data packets, while also acting as the mobility anchor for the user plane during inter-eNodeB handovers and as the anchor for mobility between LTE and other 3GPP technologies (terminating S4 interface and relaying the traffic between 2G/3G systems and PDN GW). For idle state user equipments, the SGW terminates the downlink data path and triggers paging when downlink data arrives for the user equipment. It manages and stores user equipment contexts, e.g. parameters of the IP bearer service, network internal routing information. It also performs replication of the user traffic in case of lawful interception.
The MME is the key control-node for the LTE access-network. It is responsible for idle mode user equipment tracking and paging procedure including retransmissions. It is involved in the bearer activation/deactivation process and is also responsible for choosing the SGW for a user equipment at the initial attach and at time of intra-LTE handover involving Core Network (CN) node relocation. It is responsible for authenticating the user (by interacting with the HSS). The Non-Access Stratum (NAS) signaling terminates at the MME and it is also responsible for generation and allocation of temporary identities to user equipments. It checks the authorization of the user equipment to camp on the service provider's Public Land Mobile Network (PLMN) and enforces user equipment roaming restrictions. The MME is the termination point in the network for ciphering/integrity protection for NAS signaling and handles the security key management. Lawful interception of signaling is also supported by the MME. The MME also provides the control plane function for mobility between LTE and 2G/3G access networks with the S3 interface terminating at the MME from the SGSN. The MME also terminates the S6a interface towards the home HSS for roaming user equipments.
Component Carrier Structure in LTE (Release 8)
The downlink component carrier of a 3GPP LTE system is subdivided in the time-frequency domain in so-called subframes. In 3GPP LTE each subframe is divided into two downlink slots as shown in FIG. 3, wherein the first downlink slot comprises the control channel region (PDCCH region) within the first OFDM symbols. Each subframe consists of a give number of OFDM symbols in the time domain (12 or 14 OFDM symbols in 3GPP LTE (Release 8)), wherein each OFDM symbol spans over the entire bandwidth of the component carrier. The OFDM symbols thus each consists of a number of modulation symbols transmitted on respective NRBDL×NscRB subcarriers as also shown in FIG. 4.
Assuming a multi-carrier communication system, e.g. employing OFDM, as for example used in 3GPP Long Term Evolution (LTE), the smallest unit of resources that can be assigned by the scheduler is one "resource block". A physical resource block (PRB) is defined as NsymbDL consecutive OFDM symbols in the time domain (e.g. 7 OFDM symbols) and NscRB consecutive subcarriers in the frequency domain as exemplified in FIG. 4 (e.g. 12 subcarriers for a component carrier). In 3GPP LTE (Release 8), a physical resource block thus consists of NsymbDL×NscRB resource elements, corresponding to one slot in the time domain and 180 kHz in the frequency domain (for further details on the downlink resource grid, see for example 3GPP TS 36.211, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical Channels and Modulation (Release 8)", section 6.2, available at http://www.3gpp.org and incorporated herein by reference).
One subframe consists of two slots, so that there are 14 OFDM symbols in a subframe when a so-called "normal" CP (cyclic prefix) is used, and 12 OFDM symbols in a subframe when a so-called "extended" CP is used. For sake of terminology, in the following the time-frequency resources equivalent to the same NscRB consecutive subcarriers spanning a full subframe is called a "resource block pair", or equivalent "RB pair" or "PRB pair".
The term "component carrier" refers to a combination of several resource blocks in the frequency domain. In future releases of LTE, the term "component carrier" is no longer used; instead, the terminology is changed to "cell", which refers to a combination of downlink and optionally uplink resources. The linking between the carrier frequency of the downlink resources and the carrier frequency of the uplink resources is indicated in the system information transmitted on the downlink resources.
Similar assumptions for the component carrier structure apply to later releases too.
Carrier Aggregation in LTE-A for Support of Wider Bandwidth
The frequency spectrum for IMT-Advanced was decided at the World Radio communication Conference 2007 (WRC-07). Although the overall frequency spectrum for IMT-Advanced was decided, the actual available frequency bandwidth is different according to each region or country. Following the decision on the available frequency spectrum outline, however, standardization of a radio interface started in the 3rd Generation Partnership Project (3GPP). At the 3GPP TSG RAN #39 meeting, the Study Item description on "Further Advancements for E-UTRA (LTE-Advanced)" was approved. The study item covers technology components to be considered for the evolution of E-UTRA, e.g. to fulfill the requirements on IMT-Advanced.
The bandwidth that the LTE-Advanced system is able to support is 100 MHz, while an LTE system can only support 20 MHz. Nowadays, the lack of radio spectrum has become a bottleneck of the development of wireless networks, and as a result it is difficult to find a spectrum band which is wide enough for the LTE-Advanced system. Consequently, it is urgent to find a way to gain a wider radio spectrum band, wherein a possible answer is the carrier aggregation functionality.
In carrier aggregation, two or more component carriers (component carriers) are aggregated in order to support wider transmission bandwidths up to 100 MHz. Several cells in the LTE system are aggregated into one wider channel in the LTE-Advanced system which is wide enough for 100 MHz even though these cells in LTE are in different frequency bands.
All component carriers can be configured to be LTE Rel. 8/9 compatible, at least when the aggregated numbers of component carriers in the uplink and the downlink are the same. Not all component carriers aggregated by a user equipment may necessarily be Rel. 8/9 compatible. Existing mechanism (e.g. barring) may be used to avoid Rel-8/9 user equipments to camp on a component carrier.
A user equipment may simultaneously receive or transmit one or multiple component carriers (corresponding to multiple serving cells) depending on its capabilities. A LTE-A Rel. 10 user equipment with reception and/or transmission capabilities for carrier aggregation can simultaneously receive and/or transmit on multiple serving cells, whereas an LTE Rel. 8/9 user equipment can receive and transmit on a single serving cell only, provided that the structure of the component carrier follows the Rel. 8/9 specifications.
Carrier aggregation is supported for both contiguous and non-contiguous component carriers with each component carrier limited to a maximum of 110 Resource Blocks in the frequency domain using the 3GPP LTE (Release 8/9) numerology.
It is possible to configure a 3GPP LTE-A (Release 10) compatible user equipment to aggregate a different number of component carriers originating from the same eNodeB (base station) and of possibly different bandwidths in the uplink and the downlink. The number of downlink component carriers that can be configured depends on the downlink aggregation capability of the UE. Conversely, the number of uplink component carriers that can be configured depends on the uplink aggregation capability of the UE. It may not be possible to configure a mobile terminal with more uplink component carriers than downlink component carriers.
In a typical TDD deployment, the number of component carriers and the bandwidth of each component carrier in uplink and downlink is the same. Component carriers originating from the same eNodeB need not to provide the same coverage.
The spacing between centre frequencies of contiguously aggregated component carriers shall be a multiple of 300 kHz. This is in order to be compatible with the 100 kHz frequency raster of 3GPP LTE (Release 8/9) and at the same time preserve orthogonality of the subcarriers with 15 kHz spacing. Depending on the aggregation scenario, the n×300 kHz spacing can be facilitated by insertion of a low number of unused subcarriers between contiguous component carriers.
The nature of the aggregation of multiple carriers is only exposed up to the MAC layer. For both uplink and downlink there is one HARQ entity required in MAC for each aggregated component carrier. There is (in the absence of SU-MIMO for uplink) at most one transport block per component carrier. A transport block and its potential HARQ retransmissions need to be mapped on the same component carrier.
The Layer 2 structure with activated carrier aggregation is shown in FIG. 5 and FIG. 6 for the downlink and uplink respectively.
When carrier aggregation is configured, the mobile terminal only has one RRC connection with the network. At RRC connection establishment/re-establishment, one cell provides the security input (one ECGI, one PCI and one ARFCN) and the non-access stratum mobility information (e.g. TAI) similarly as in LTE Rel. 8/9. After RRC connection establishment/re-establishment, the component carrier corresponding to that cell is referred to as the downlink Primary Cell (PCell). There is always one and only one downlink PCell (DL PCell) and one uplink PCell (UL PCell) configured per user equipment in connected state. Within the configured set of component carriers, other cells are referred to as Secondary Cells (SCells); with carriers of the SCell being the Downlink Secondary Component Carrier (DL SCC) and Uplink Secondary Component Carrier (UL SCC). The characteristics of the downlink and uplink PCell are:                1. For each SCell the usage of uplink resources by the UE, in addition to the downlink ones is configurable; the number of DL SCCs configured is therefore always larger or equal to the number of UL SCCs, and no SCell can be configured for usage of uplink resources only        2. The uplink PCell is used for transmission of Layer 1 uplink control information        3. The downlink PCell cannot be de-activated, unlike SCells        4. From UE perspective, each uplink resource only belongs to one serving cell        5. The number of serving cells that can be configured depends on the aggregation capability of the UE        6. Re-establishment is triggered when the downlink PCell experiences Rayleigh fading (RLF), not when downlink SCells experience RLF        7. The downlink PCell cell can change with handover (i.e. with security key change and RACH procedure)        8. Non-access stratum information is taken from the downlink PCell        9. PCell can only be changed with handover procedure (i.e. with security key change and RACH procedure)        10. PCell is used for transmission of PUCCH
The configuration and reconfiguration of component carriers can be performed by RRC. Activation and deactivation is done via MAC control elements. At intra-LTE handover, RRC can also add, remove, or reconfigure SCells for usage in the target cell. When adding a new SCell, dedicated RRC signaling is used for sending the system information of the SCell, the information being necessary for transmission/reception (similarly as in Rel-8/9 for handover).
When a user equipment is configured with carrier aggregation there is one pair of uplink and downlink component carriers that is always active. The downlink component carrier of that pair might be also referred to as DL anchor carrier'. Same applies also for the uplink.
When carrier aggregation is configured, a user equipment may be scheduled over multiple component carriers simultaneously but at most one random access procedure shall be ongoing at any time. Cross-carrier scheduling allows the PDCCH of a component carrier to schedule resources on another component carrier. For this purpose a component carrier identification field is introduced in the respective DCI formats, called CIF.
A linking between uplink and downlink component carriers allows identifying the uplink component carrier for which the grant applies when there is no-cross-carrier scheduling. The linkage of downlink component carriers to uplink component carrier does not necessarily need to be one to one. In other words, more than one downlink component carrier can link to the same uplink component carrier. At the same time, a downlink component carrier can only link to one uplink component carrier.
Logical and Transport Channels
The MAC layer provides a data transfer service for the RLC layer through logical channels. Logical channels are either Control Logical Channels which carry control data such as RRC signalling, or Traffic Logical Channels which carry user plane data. Broadcast Control Channel (BCCH), Paging Control channel (PCCH), Common Control Channel (CCCH), Multicast Control Channel (MCCH) and Dedicated Control Channel (DCCH) are Control Logical Channels. Dedicated Traffic channel (DTCH) and Multicast Traffic Channel (MTCH) are Traffic Logical Channels.
Data from the MAC layer is exchanged with the physical layer through Transport Channels. Data is multiplexed into transport channels depending on how it is transmitted over the air. Transport channels are classified as downlink or uplink as follows. Broadcast Channel (BCH), Downlink Shared Channel (DL-SCH), Paging Channel (PCH) and Multicast Channel (MCH) are downlink transport channels, whereas the Uplink Shared Channel (UL-SCH) and the Random Access Channel (RACH) are uplink transport channels.
A multiplexing is then performed between logical channels and transport channels in the downlink and uplink respectively.
Layer 1/Layer 2 (L1/L2) Control Signaling
In order to inform the scheduled users about their allocation status, transport format and other data-related information (e.g. HARQ information, transmit power control (TPC) commands), L1/L2 control signaling is transmitted on the downlink along with the data. L1/L2 control signaling is multiplexed with the downlink data in a subframe, assuming that the user allocation can change from subframe to subframe. It should be noted that user allocation might also be performed on a TTI (Transmission Time Interval) basis, where the TTI length can be a multiple of the subframes. The TTI length may be fixed in a service area for all users, may be different for different users, or may even by dynamic for each user. Generally, the L1/2 control signaling needs only to be transmitted once per TTI. Without loss of generality, the following assumes that a TTI is equivalent to one subframe.
The L1/L2 control signaling is transmitted on the Physical Downlink Control Channel (PDCCH). A PDCCH carries a message as a Downlink Control Information (DCI), which includes resource assignments and other control information for a mobile terminal or groups of UEs. In general, several PDCCHs can be transmitted in one subframe.
It should be noted that in 3GPP LTE, assignments for uplink data transmissions, also referred to as uplink scheduling grants or uplink resource assignments, are also transmitted on the PDCCH.
With respect to scheduling grants, the information sent on the L1/L2 control signaling may be separated into the following two categories, Shared Control Information (SCI) carrying Cat 1 information and Downlink Control Information (DCI) carrying Cat 2/3 information.
Shared Control Information (SCI) Carrying Cat 1 Information
The shared control information part of the L1/L2 control signaling contains information related to the resource allocation (indication). The shared control information typically contains the following information:                A user identity indicating the user(s) that is/are allocated the resources.        RB allocation information for indicating the resources (Resource Blocks (RBs)) on which a user(s) is/are allocated. The number of allocated resource blocks can be dynamic.        The duration of assignment (optional), if an assignment over multiple sub-frames (or TTIs) is possible.
Depending on the setup of other channels and the setup of the Downlink Control Information (DCI)—see below—the shared control information may additionally contain information such as ACK/NACK for uplink transmission, uplink scheduling information, information on the DCI (resource, MCS, etc.).
Downlink Control Information (DCI) Carrying Cat 2/3 Information
The downlink control information part of the L1/L2 control signaling contains information related to the transmission format (Cat 2 information) of the data transmitted to a scheduled user indicated by the Cat 1 information. Moreover, in case of using (Hybrid) ARQ as a retransmission protocol, the Cat 2 information carries HARQ (Cat 3) information. The downlink control information needs only to be decoded by the user scheduled according to Cat 1. The downlink control information typically contains information on:                Cat 2 information: Modulation scheme, transport-block (payload) size or coding rate, MIMO (Multiple Input Multiple Output)-related information, etc. Either the transport-block (or payload size) or the code rate can be signaled. In any case these parameters can be calculated from each other by using the modulation scheme information and the resource information (number of allocated resource blocks)        Cat 3 information: HARQ related information, e.g. hybrid ARQ process number, redundancy version, retransmission sequence number
Downlink control information occurs in several formats that differ in overall size and also in the information contained in its fields. The different DCI formats that are currently defined for LTE are described in detail in 3GPP TS 36.212, "Multiplexing and channel coding", section 18.104.22.168 (available at http://www.3gpp.org and incorporated herein by reference).
Uplink Control Information (UCI)
In general, uplink control signaling in mobile communication systems can be divided into two categories:                Data-associated control signaling, is control signaling which is always transmitted together with uplink data and is used in the processing of that data. Examples include transport format indications, "New data" Indicator (NDIs) and MIMO parameters.        Control signaling not associated with data is transmitted independently of any uplink data packet. Examples include HARQ Acknowledgements (ACK/NACK) for downlink data packets, Channel Quality Indicators (CQIs) to support link adaptation, and MIMO feedback such as Rank Indicators (RIs) and Precoding Matrix Indicators (PMI) for downlink transmissions. Scheduling Requests (SRs) for uplink transmissions also fall into this category.
Uplink data-associated control signaling is not necessary in LTE, as the relevant information is already known to the eNodeB. Therefore, only data-non-associated control signaling exists in the LTE uplink.
Consequently, the UCI can consist of:                Scheduling Requests (SRs)        HARQ ACK/NACK in response to downlink data packets on the PDSCH (Physical Downlink Shared CHannel). One ACK/NACK bit is transmitted in the case of single-codeword downlink transmission while two ACK/NACK bits are used in the case of two-codeword downlink transmission.        Channel State Information (CSI) which includes CQls as well as the MIMO-related feedback consisting of RIs (Rank Indicator) and PMI (Precoding Matrix Indicator). 20 bits per subframe are used for the CSI. Channel state information which is required in the eNB for scheduling of downlink data transmissions.
The amount of UCI a UE can transmit in a subframe depends on the number of SC-FDMA symbols available for transmission of control signaling data. The PUCCH supports eight different formats, depending on the amount of information to be signaled. The following UCI formats on PUCCH are supported, according to the following overview
PUCCHFormatUplink Control Information (UCI)Format 1Scheduling Request (SR) (unmodulated waveform)Format 1a1-bit HARQ ACK/NACK with/without SRFormat 1b2-bit HARQ ACK/NACK with/without SRFormat 2CSI (20 coded bits)Format 2CSI and 1- or 2-bit HARQ ACK/NACK for extended CP onlyFormat 2aCSI and 1-bit HARQ ACK/NACK (20 + 1 coded bits)Format 2bCSI and 2-bit HARQ ACK/NACK (20 + 2 coded bits)Format 3Multiple ACK/NACKs for carrier aggregation:up to 20 ACK/NACK bits plus optional SR, in 48 coded bits
Using the different defined PUCCH formats (according to 5.4.1 and 5.4.2 of TS 36.211), the following combinations of UCI on PUCCH are supported (see Section 10.1.1 of TS 36.213):                Format 1a for 1-bit HARQ-ACK or in case of FDD for 1-bit HARQ-ACK with positive SR        Format 1b for 2-bit HARQ-ACK or for 2-bit HARQ-ACK with positive SR        Format 1b for up to 4-bit HARQ-ACK with channel selection when the UE is configured with more than one serving cell or, in the case of TDD, when the UE is configured with a single serving cell        Format 1 for positive SR        Format 2 for a CSI report when not multiplexed with HARQ-ACK        Format 2a for a CSI report multiplexed with 1-bit HARQ-ACK for normal cyclic prefix        Format 2b for a CSI report multiplexed with 2-bit HARQ-ACK for normal cyclic prefix        Format 2 for a CSI report multiplexed with HARQ-ACK for extended cyclic prefix        Format 3 for up to 10-bit HARQ-ACK for FDD and for up to 20-bit HARQ-ACK for TDD        Format 3 for up to 11-bit corresponding to 10-bit HARQ-ACK and 1-bit positive/negative SR for FDD and for up to 21-bit corresponding to 20-bit HARQ-ACK and 1-bit positive/negative SR for TDD.        Format 3 for multi-cell HARQ-ACK, 1-bit positive/negative SR and a CSI report for one serving cell.Downlink & Uplink Data Transmission
Regarding downlink data transmission, L1/L2 control signaling is transmitted on a separate physical channel (PDCCH), along with the downlink packet data transmission. This L1/L2 control signaling typically contains information on:                The physical resource(s) on which the data is transmitted (e.g. subcarriers or subcarrier blocks in case of OFDM, codes in case of CDMA). This information allows the mobile terminal (receiver) to identify the resources on which the data is transmitted.        When user equipment is configured to have a Carrier Indication Field (CIF) in the L1/L2 control signaling, this information identifies the component carrier for which the specific control signaling information is intended. This enables assignments to be sent on one component carrier which are intended for another component carrier ("cross-carrier scheduling"). This other, cross-scheduled component carrier could be for example a PDCCH-less component carrier, i.e. the cross-scheduled component carrier does not carry any L1/L2 control signaling.        The Transport Format, which is used for the transmission. This can be the transport block size of the data (payload size, information bits size), the MCS (Modulation and Coding Scheme) level, the Spectral Efficiency, the code rate, etc. This information (usually together with the resource allocation (e.g. the number of resource blocks assigned to the user equipment)) allows the user equipment (receiver) to identify the information bit size, the modulation scheme and the code rate in order to start the demodulation, the de-rate-matching and the decoding process. The modulation scheme may be signaled explicitly.        Hybrid ARQ (HARQ) information:                    HARQ process number: Allows the user equipment to identify the hybrid ARQ process on which the data is mapped.            Sequence number or new data indicator (NDI): Allows the user equipment to identify if the transmission is a new packet or a retransmitted packet. If soft combining is implemented in the HARQ protocol, the sequence number or new data indicator together with the HARQ process number enables soft-combining of the transmissions for a PDU prior to decoding.            Redundancy and/or constellation version: Tells the user equipment, which hybrid ARQ redundancy version is used (required for de-rate-matching) and/or which modulation constellation version is used (required for demodulation).                        UE Identity (UE ID): Tells for which user equipment the L1/L2 control signaling is intended for. In typical implementations this information is used to mask the CRC of the L1/L2 control signaling in order to prevent other user equipments to read this information.
To enable an uplink packet data transmission, L1/L2 control signaling is transmitted on the downlink (PDCCH) to tell the user equipment about the transmission details. This L1/L2 control signaling typically contains information on:                The physical resource(s) on which the user equipment should transmit the data (e.g. subcarriers or subcarrier blocks in case of OFDM, codes in case of CDMA).        When user equipment is configured to have a Carrier Indication Field (CIF) in the L1/L2 control signaling, this information identifies the component carrier for which the specific control signaling information is intended. This enables assignments to be sent on one component carrier which are intended for another component carrier. This other, cross-scheduled component carrier may be for example a PDCCH-less component carrier, i.e. the cross-scheduled component carrier does not carry any L1/L2 control signaling.        L1/L2 control signaling for uplink grants is sent on the DL component carrier that is linked with the uplink component carrier or on one of the several DL component carriers, if several DL component carriers link to the same UL component carrier.        The Transport Format, the user equipment should use for the transmission. This can be the transport block size of the data (payload size, information bits size), the MCS (Modulation and Coding Scheme) level, the Spectral Efficiency, the code rate, etc. This information (usually together with the resource allocation (e.g. the number of resource blocks assigned to the user equipment)) allows the user equipment (transmitter) to pick the information bit size, the modulation scheme and the code rate in order to start the modulation, the rate-matching and the encoding process. In some cases the modulation scheme maybe signaled explicitly.        Hybrid ARQ information:                    HARQ Process number: Tells the user equipment from which hybrid ARQ process it should pick the data.            Sequence number or new data indicator: Tells the user equipment to transmit a new packet or to retransmit a packet. If soft combining is implemented in the HARQ protocol, the sequence number or new data indicator together with the HARQ process number enables soft-combining of the transmissions for a protocol data unit (PDU) prior to decoding.            Redundancy and/or constellation version: Tells the user equipment, which hybrid ARQ redundancy version to use (required for rate-matching) and/or which modulation constellation version to use (required for modulation).                        UE Identity (UE ID): Tells which user equipment should transmit data. In typical implementations this information is used to mask the CRC of the L1/L2 control signaling in order to prevent other user equipments to read this information.
There are several different possibilities how to exactly transmit the information pieces mentioned above in uplink and downlink data transmission. Moreover, in uplink and downlink, the L1/L2 control information may also contain additional information or may omit some of the information. For example:                HARQ process number may not be needed, i.e. is not signaled, in case of a synchronous HARQ protocol.        A redundancy and/or constellation version may not be needed, and thus not signaled, if Chase Combining is used (always the same redundancy and/or constellation version) or if the sequence of redundancy and/or constellation versions is pre-defined.        Power control information may be additionally included in the control signaling.        MIMO related control information, such as e.g. pre-coding, may be additionally included in the control signaling.        In case of multi-codeword MIMO transmission transport format and/or HARQ information for multiple code words may be included.
For uplink resource assignments (on the Physical Uplink Shared Channel (PUSCH)) signaled on PDCCH in LTE, the L1/L2 control information does not contain a HARQ process number, since a synchronous HARQ protocol is employed for LTE uplink. The HARQ process to be used for an uplink transmission is given by the timing. Furthermore, it should be noted that the redundancy version (RV) information is jointly encoded with the transport format information, i.e. the RV info is embedded in the transport format (TF) field. The Transport
Format (TF) respectively modulation and coding scheme (MCS) field has for example a size of 5 bits, which corresponds to 32 entries. 3 TF/MCS table entries are reserved for indicating redundancy versions (RVs) 1, 2 or 3. The remaining MCS table entries are used to signal the MCS level (TBS) implicitly indicating RVO. The size of the CRC field of the PDCCH is 16 bits.
For downlink assignments (PDSCH) signaled on PDCCH in LTE the Redundancy Version (RV) is signaled separately in a two-bit field. Furthermore the modulation order information is jointly encoded with the transport format information. Similar to the uplink case there is 5 bit MCS field signaled on PDCCH. 3 of the entries are reserved to signal an explicit modulation order, providing no Transport format (Transport block) info. For the remaining 29 entries modulation order and Transport block size info are signaled.
Further detailed information on the control information can be found in 3GPP TS 36.212 Section 5.3.3 and 3GPP 36.213 Sections 7.1.7 and 8.6, incorporated herein by reference.
Channel Quality Reporting—CSI
The principle of link adaptation is fundamental to the design of a radio interface which is efficient for packet-switched data traffic. Unlike the early versions of UMTS (Universal Mobile Telecommunication System), which used fast closed-loop power control to support circuit-switched services with a roughly constant data rate, link adaptation in LTE adjusts the transmitted data rate (modulation scheme and channel coding rate) dynamically to match the prevailing radio channel capacity for each user.
For the downlink data transmissions in LTE, the eNodeB typically selects the modulation scheme and code rate (MCS) depending on a prediction of the downlink channel conditions. An important input to this selection process is the Channel State Information (CSI) feedback transmitted by the User Equipment (UE) in the uplink to the eNodeB.
Channel state information is used in a multi-user communication system, such as for example 3GPP LTE to determine the quality of channel resource(s) for one or more users. In general, in response to the CSI feedback the eNodeB can select between QPSK, 16-QAM and 64-QAM schemes and a wide range of code rates. This CSI information may be used to aid in a multi-user scheduling algorithm to assign channel resources to different users, or to adapt link parameters such as modulation scheme, coding rate or transmit power, so as to exploit the assigned channel resources to its fullest potential.
The CSI is reported for every component carrier, and, depending on the reporting mode and bandwidth, for different sets of subbands of the component carrier. In 3GPP LTE, the smallest unit for which channel quality is reported is called a subband, which consists of multiple frequency-adjacent resource blocks.
As described before, user equipments will usually not perform and report CSI measurements on configured but deactivated downlink component carriers but only radio resource management related measurements like RSRP (Reference Signal Received Power) and RSRQ (Reference Signal Received Quality).
Details about the involved reporting and transmission mechanisms are given in the following specifications to which it is referred for further reading (all documents available at http://www.3gpp.org and incorporated herein by reference):                3GPP TS 36.211, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical channels and modulation", version 10.0.0, particularly sections 6.3.3, 6.3.4,        3GPP TS 36.212, "Evolved Universal Terrestrial Radio Access (E-UTRA); Multiplexing and channel coding", version 10.0.0, particularly sections 5.2.2, 5.2.4, 5.3.3,        3GPP TS 36.213, "Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures", version 10.0.1, particularly sections 7.1.7, and 7.2.
The periodicity and frequency resolution to be used by a UE to report on the CSI are both controlled by the eNodeB. The Physical Uplink Control Channel (PUCCH) is used for periodic CSI reporting only (i.e. CSI reporting with a specific periodicity configured by RRC); the PUSCH is used for aperiodic reporting of the CSI, whereby the eNodeB specifically instructs (by a PDCCH) the UE to send an individual CSI report embedded into a resource which is scheduled for uplink data transmission.
Sounding Reference Symbol (SRS)
The SRS are important for uplink channel sounding to support dynamic uplink resource allocation, as well as for reciprocity-aided beamforming in the downlink. Uplink Sounding Reference Signals (SRS) are mainly used for channel quality estimation of the uplink channel which in turn is used as an input for the uplink scheduler, e.g. it enables frequency-selective scheduling.
Release 10 introduces the possibility of dynamically triggering individual SRS transmissions via the PDCCH; these dynamic aperiodic SRS transmissions are known as "type-1" SRSs, while the Release 8 periodic RRC-configured SRSs are known as "type-0" in Release 10.
An indicator in an uplink resource grant on the PDCCH can be used to trigger a single type 1 SRS transmission. This facilitates rapid channel sounding to respond to changes in traffic or channel conditions, without typing up SRS resources for a long period. In DCI format 0, one new bit can indicate activation of a type 1 SRS according to a set of parameters that is configured beforehand by RRC signaling. In DCI format 4, which is used for scheduling uplink SU-MIMO transmissions, two new bits allow one of three sets of RRC-configured type 1 SRS transmission parameters to be triggered.
The SRS transmissions are always in the last SC-FDMA symbol of the corresponding subframe where reporting is configured/scheduled. PUSCH data transmission is not permitted on the SC-FDMA signal designated for SRS, i.e. PUSCH transmission is punctured such that all symbols but the last are used for PUSCH.
Uplink Control Signaling and Multiplexing
When simultaneous uplink PUSCH data and control signaling are scheduled, the control signaling is normally multiplexed together with the data (in PUSCH) prior to the DFT spreading, in order to preserve the single-carrier low Cubic Metric (CM) property of the uplink transmission. The uplink control channel, PUCCH, is used by a UE to transmit any necessary control signaling only in subframes in which the UE has not been allocated any RBs for PUSCH transmission.
Further information on the multiplexing of the uplink control signaling can be found in Chapters 18.104.22.168, 16.3.3, 16.3.4, 16.3.5, 16.3.6, 16.3.7, 16.4 of LTE—The UMTS Long Term Evolution—From Theory to Practice, Edited by Stefanie Sesia, Issam Toufik, Matthew Baker, Second Edition, incorporated herein by reference
Time Division Duplex—TDD
LTE can operate in Frequency-Division-Duplex (FDD) and Time-Division-Duplex (TDD) modes in a harmonized framework, designed also to support the evolution of TD-SCDMA
(Time-Division Synchronous Code Division Multiple Access). TDD separates the uplink and downlink transmissions in the time domain, while the frequency may stay the same.
The term "duplex" refers to bidirectional communication between two devices, distinct from unidirectional communication. In the bidirectional case, transmissions over the link in each direction may take place at the same time ("full duplex") or at mutually exclusive times ("half duplex").
For TDD in the unpaired radio spectrum, the basic structure of RBs and REs is depicted in FIG. 4, but only a subset of the subframes of a radio frame are available for downlink transmissions; the remaining subframes are used for uplink transmissions, or for special subframes. Special subframes are important to allow uplink transmission timings to be advanced, so as to make sure that transmitted signals from the UEs (i.e. uplink) arrive roughly at the same time at the eNodeB. Since the signal propagation delay is related to the distance between transmitter and receiver (neglecting reflection and other similar effects), this means that a signal transmitted by a UE near the eNodeB travels for a short time than the signals transmitted by a UE far from the eNodeB. In order to arrive at the same time, the far UE has to transmit its signal earlier than the near UE, which is solved by the so-called "timing advance" procedure in 3GPP systems. In TDD this has the additional circumstance that the transmission and reception occur on the same carrier frequency, i.e. downlink and uplink need to be duplexed in time domain. While a UE far from the eNodeB needs to start uplink transmission earlier than the near UE, conversely, a downlink signal is received by a near UE earlier than by the far UE. In order to be able to switch the circuitry from DL reception to UL transmission, guard time is defined in the special subframe. To additionally take care of the timing advanace problem, the guard time for a far UE needs to be longer than for a near UE.
This TDD structure is known as "Frame Structure Type 2" in 3GPP LTE Release 8 and later, of which seven different uplink-downlink configurations are defined, which allow a variety of downlink-uplink ratios and switching periodicities. FIG. 7 illustrates the table with the 7 different TDD uplink-downlink configurations, indexed from 0-6, where "D" shall indicate a downlink subframe, "U" an uplink subframe and "S" a special subframe. As can be seen therefrom, the seven available TDD uplink-downlink configurations can provide between 40% and 90% of downlink subframes (when, for simplicity, counting a special subframe as a downlink subframe, since part of such a subframe is available for downlink transmission).
FIG. 8 shows the frame structure type 2, particularly for a 5 ms switch-point periodicity, i.e. for TDD configurations 0, 1, 2 and 6.
FIG. 8 illustrates a radio frame, being 10 ms in length, and the corresponding two half-frames of 5 ms each. The radio frame consists of 10 subframes with each 1 ms, where each of the subframes is assigned the type of uplink, downlink or special, as defined by one of the Uplink-downlink configurations according to the table of FIG. 7.
As can be appreciated from FIG. 7, subframe #1 is always a Special subframe, and subframe #6 is a Special subframe for TDD configurations 0, 1, 2 and 6; for TDD configurations 3, 4 and 5, subframe #6 is destined for downlink. Special subframes include three fields: DwPTS (Downlink Pilot Time Slot), the GP (Guard Period) and UpPTS (Uplink Pilot Time Slot). The following Table shows information on the special subframe and in particular lists the lengths of DwPTS (Downlink Pilot Time Slot), the GP (Guard Period) and of UpPTS (Uplink Pilot Time Slot) as a multiple of the sample time Ts=(1/30720) ms as defined for 3GPP LTE Release 11.
TABLEspecial subframe configurations, Frame Structure Type 2Normal cyclic prefix in downlinkExtended cyclic prefix in downlinkUpPTSUpPTSNormalExtendedNormalExtendedSpecialcycliccycliccycliccyclicsubframeprefix inprefix inprefix inprefix inconfigurationDwPTSuplinkuplinkDwPTSuplinkuplink0 6592 · Ts2192 · Ts2560 · Ts 7680 · Ts2192 · Ts2560 · Ts119760 · Ts20480 · Ts221952 · Ts23040 · Ts324144 · Ts25600 · Ts426336 · Ts 7680 · Ts4384 · Ts5120 · Ts5 6592 · Ts4384 · Ts5120 · Ts20480 · Ts619760 · Ts23040 · Ts721952 · Ts12800 · Ts824144 · Ts———913168 · Ts———
The TDD configuration applied in the system has an impact on many operations performed at the mobile station and base station, such as radio resource management (RRM) measurements, channel state information (CSI) measurements, channel estimations, PDCCH detection and HARQ timings.
In particular, the UE reads the system information to learn about the TDD configuration in its current cell, i.e. which subframe to monitor for measurement, for CSI measure and report, for time domain filtering to get channel estimation, for PDCCH detection, or for UL/DL ACK/NACK feedback.
Hybrid ARQ Schemes
A common technique for error detection and correction in packet transmission systems over unreliable channels is called hybrid Automatic Repeat request (HARQ), which is a combination of Forward Error Correction (FEC) and ARQ.
If a FEC encoded packet is transmitted and the receiver fails to decode the packet correctly (errors are usually checked by a CRC (Cyclic Redundancy Check)), the receiver requests a retransmission of the packet. Generally (and throughout this document) the transmission of additional information is called "retransmission (of a packet)", although this retransmission does not necessarily mean a transmission of the same encoded information, but could also mean the transmission of any information belonging to the packet (e.g. additional redundancy information).
Depending on the information (generally code-bits/symbols), of which the transmission is composed, and depending on how the receiver processes the information, the following Hybrid ARQ schemes are defined: Type I, Type II and Type III HARQ.
Synchronous HARQ means that the re-transmissions of HARQ blocks occur at pre-defined periodic intervals. Hence, no explicit signaling is required to indicate to the receiver the retransmission schedule. Asynchronous HARQ offers the flexibility of scheduling re-transmissions based on air interface conditions. In this case some identification of the HARQ process needs to be signaled in order to allow for a correct combining and protocol operation. In 3GPP LTE systems, HARQ operations with eight processes are used. The HARQ protocol operation for downlink data transmission will be similar or even identical to HSDPA.
In uplink HARQ protocol operation there are two different options on how to schedule a retransmission. Retransmissions are either "scheduled" by a NACK (also referred to as a synchronous non-adaptive retransmission) or are explicitly scheduled by the network by transmitting a PDCCH (also referred to as synchronous adaptive retransmissions). In case of a synchronous non-adaptive retransmission the retransmission will use the same parameters as the previous uplink transmission, i.e. the retransmission will be signaled on the same physical channel resources, respectively uses the same modulation scheme/transport format.
Since synchronous adaptive retransmissions are explicitly scheduled via PDCCH, the eNodeB has the possibility to change certain parameters for the retransmission. It should be noted that the HARQ feedback (ACK/NACK) and PDCCH signaling occurs at the same timing. Therefore the user equipment only needs to check once whether a synchronous non-adaptive retransmission is triggered (i.e. only a NACK is received) or whether eNode B requests a synchronous adaptive retransmission (i.e. PDCCH is signaled).
HARQ and Control Signaling for TDD Operation
As explained above, transmission of downlink or uplink data with HARQ requires that an ACKnowledgement ACK or Negative ACK be sent in the opposite direction to inform the transmitting side of the success or failure of the packet reception.
In case of FDD operation, acknowledgement indicators related to data transmission in a subframe n are transmitted in the opposite direction during subframe n+4, such that a one-to-one synchronous mapping exists between the instant at which the transport is transmitted and its corresponding acknowledgment.
However, in the case of TDD operation, subframes are designated on a cell-specific basis as uplink or downlink or special (see previous chapter), thereby constraining the times at which resource grants, data transmissions, acknowledgments and retransmissions can be sent in their respective directions. The LTE design for TDD therefore supports grouped ACK/NACK transmission to carry multiple acknowledgements within one subframe.
For uplink HARQ, the sending (in one downlink subframe) of multiple acknowledgements on the Physical Hybrid ARQ Indicator CHannel (PHICH) is not problematic since, when viewed from the eNodeB, this is not significantly different from the case in which single acknowledgements are sent simultaneously to multiple UEs. However, for downlink HARQ, if the asymmetry is downlink-biased, the uplink control signaling (PUCCH) formats of FDD are insufficient to carry the additional ACK/NACK information. Each of the TDD subframe configurations in LTE (see below, and FIG. 7) has its own such mapping predefined between downlink and uplink subframes for HARQ purposes, with the mapping being designed to achieve a balance between minimization of acknowledgment delay and an even distribution of ACK/NACKs across the available uplink subframes. Further details are provided in TS 36.213 v11.1.0 "3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures (Release 11)" Chapter 7.3 incorporated herewith by reference.
Small Cells
Explosive demands for mobile data are driving changes in how mobile operators will need to respond to the challenging requirements of higher capacity and improved Quality of user Experience (QoE). Currently, fourth generation wireless access systems using Long Term Evolution (LTE) are being deployed by many operators worldwide in order to offer faster access with lower latency and more efficiency than 3G/3.5G system. Nevertheless, the anticipated future traffic growth is so tremendous that there is a vastly increased need for further network densification to handle the capacity requirements, particularly in high traffic areas (hot spot areas) that generate the highest volume of traffic. Network densification—increasing the number of network nodes, thereby bringing them physically closer to the user terminals—is a key to improving traffic capacity and extending the achievable user-data rates of a wireless communication system.
In addition to straightforward densification of a macro deployment, network densification can be achieved by the deployment of complementary low-power nodes respectively small cells under the coverage of an existing macro-node layer. In such a heterogeneous deployment, the low-power nodes provide very high traffic capacity and very high user throughput locally, for example in indoor and outdoor hotspot positions. Meanwhile, the macro layer ensures service availability and QoE over the entire coverage area. In other words, the layer containing the low-power nodes can also be referred to as providing local-area access, in contrast to the wide-area-covering macro layer.
The installation of low-power nodes respectively small cells as well as heterogeneous deployments has been possible since the first release of LTE. In this regard, a number of solutions have been specified in recent releases of LTE (i.e., Release-10/11). More specifically, these releases introduced additional tools to handle inter-layer interference in heterogeneous deployments. In order to further optimize performance and provide cost/energy-efficient operation, small cells require further enhancements and in many cases need to interact with or complement existing macro cells. Such solutions will be investigated during the further evolution of LTE—Release 12 and beyond. In particular further enhancements related to low-power nodes and heterogeneous deployments will be considered under the umbrella of the new Rel-12 study item (SI) "Study on Small Cell Enhancements for E-UTRA and E-UTRAN". Some of these activities will focus on achieving an even higher degree of interworking between the macro and low-power layers, including different forms of macro assistance to the low-power layer and dual-layer connectivity. Dual connectivity implies that the device has simultaneous connections to both macro and low-power layers.
Some deployment scenarios assumed in this study item on small cell enhancements will be discussed below. In the following scenarios, the backhaul technologies categorized as non-ideal backhaul in TR 36.932 [3] are assumed. Fibre access which can be used to deploy Remote Radio Heads (RRHs) is not assumed in this study. HeNBs are not precluded, but not distinguished from Pico eNBs in terms of deployment scenarios and challenges even though the transmission power of HeNBs is lower than that of Pico eNBs. The following 3 scenarios are considered.
Scenario #1
Scenario #1 is illustrated in FIG. 9 and is the deployment scenario where macro and small cells on the same carrier frequency (intra-frequency) are connected via a non-ideal backhaul. User are distributed both for outdoor and indoor.
Scenario #2
Scenario #2 is illustrated in FIGS. 10 and 11 and refers to a deployment scenario where macro and small cells on different carrier frequencies (inter-frequency) are connected via a non-ideal backhaul. User are distributed both for outdoor and indoor. There are essentially two different scenarios #2, referred herein as 2a and 2b, the difference being that in scenario 2b an indoor small cell deployment is considered.
Scenario #3 is illustrated in FIG. 12 and refers to a deployment scenario where only small cells on one or more carrier frequencies are connected via a non-ideal backhaul link.
Depending on the deployment scenario, different challenges/problems exist which need to be further investigated. During the study item phase such challenges have been identified for the corresponding deployment scenarios and captured in TS 36.842; more details on those challenges/problems can be found there.
In order to resolve the identified challenges which are described in section 5 of TS36.842, the following design goals are taken into account for this study in addition to the requirements specified in TR 36.932.
In terms of mobility robustness:                For UEs in RRC_CONNECTED, Mobility performance achieved by small cell deployments should be comparable with that of a macro-only network.
In terms of increased signaling load due to frequent handover:                Any new solutions should not result in excessive increase of signaling load towards the Core Network. However, additional signaling and user plane traffic load caused by small cell enhancements should also be taken into account.
In terms of improving per-user throughput and system capacity:                Utilising radio resources across macro and small cells in order to achieve per-user throughput and system capacity similar to ideal backhaul deployments while taking into account QoS requirements should be targeted.Dual Connectivity
One promising solution to the problems which are currently under discussion in 3GPP RAN working groups is the so-called "dual connectivity" concept. The term "dual connectivity" is used to refer to an operation where a given UE consumes radio resources provided by at least two different network nodes connected with a non-ideal backhaul. Essentially, the UE is connected with both a macro cell (macro eNB) and small cell (secondary or small eNB). Furthermore, each eNB involved in dual connectivity for a UE may assume different roles. Those roles do not necessarily depend on the eNB's power class and can vary among UEs.
Since the study Item is currently at a very early stage, details on the dual connectivity are not decided yet. For example the architecture has not been agreed on yet. Therefore, many issues/details, e.g. protocol enhancements, are still open currently. FIG. 13 shows an exemplary architecture for dual connectivity. It should be only understood as one potential option; the invention is not limited to this specific network/protocol architecture but can be applied generally. The following assumptions on the architecture are made here:                Per bearer level decision where to serve each packet, C/U plane split                    As an example UE RRC signalling and high QoS data such as VoLTE can be served by the Macro cell, while best effort data is offloaded to the small cell.                        No coupling between bearers, so no common PDCP or RLC required between the Macro cell and small cell        Looser coordination between RAN nodes        SeNB has no connection to S-GW, i.e. packets are forwarded by MeNB        Small Cell is transparent to CN.
Regarding the last two bullet points, it should be noted that it's also possible that SeNB is connected directly with the S-GW, i.e. S1-U is between S-GW and SeNB. Essentially there are three different options w.r.t the bearer mapping/splitting:                Option 1: S1-U also terminates in SeNB; depicted in FIG. 14a         Option 2: S1-U terminates in MeNB, no bearer split in RAN; depicted in FIG. 14b         Option 3: S1-U terminates in MeNB, bearer split in RAN; depicted in FIG. 14c
FIG. 14a-c depict those three options taking the downlink direction for the U-Plane data as an example. For explanation purpose, option 2 is mainly assumed for this application, and is the basis for FIG. 13 too.
Shortcomings of Dual Connectivity for Uplink
As explained above, the main idea of the dual connectivity concept is that a UE is communicating to both the MeNB and at least one SeNB. The usage of radio resources from both links offers the opportunity to increase the capacity/throughput.
Even though details of the dual connectivity are not decided yet (as mentioned before), it may assumed that UE has the possibility to listen and/or transmit on multiple frequencies simultaneously. For example, dual UL transmission has an advantage of achieving higher peak throughput by simultaneously transmitting on multiple CCs in one TTI (e.g. subframe).
However, especially for the uplink direction there would be some challenging issues to be resolved, e.g. inter-modulation distortion (IMD) caused by simultaneous transmission on multiple CCs. For some band combinations, if IM products occur in the spectrum range of the other system, IMD has to be suppressed somehow. To overcome such mentioned issues, an additional insertion loss could be introduced, e.g. additional RF filter is inserted into UE RF components. However, this additional insertion loss would essentially shrink the UL coverage even for the case that UE is configured only with one carrier. As another alternative countermeasure, power reduction for the case of simultaneous transmission was mentioned. Essentially, additional power reduction like P-MPR or A-MPR is applied if UE transmits on multiple CCs in a TTI simultaneously. However, with this alternative the additional power reduction will also shrink the UL coverage of the area where UE can simultaneously transmits on 2 CCs. In addition, it was no so clear whether this solution would resolve some issues, e.g. blocking, on simultaneous transmission.
Considering the described complexity from UE RF point of view and also from baseband point of view, for support of dual Uplink Transmissions it would be quite likely that especially low end category UEs (probably be being, at least at the beginning, more numerous than more expensive ones) would not support dual uplink transmission.
Also, it should be kept in mind that the amount of different band combinations for carrier-aggregation-capable UEs are increasing all the time as new bands and band combinations are being acquired by operators around the world. Considering this excessive amount of different band combinations, it seems quite unlikely that a single UE could support all different small cell deployment band combinations.
Therefore, solutions for small cell deployments need to be designed in a way that also UEs which do not support dual Rx or dual Tx could get gains and thus benefit from dual connectivity support.

Uplink switching of communication links for mobile stations in dual connectivity

Panasonic Intellectual Property Corporation of America


A camera having a blurring correction apparatus according to the present invention includes a photographic lens for forming an image of an object to be photographed, a detecting apparatus for detecting the degree of movement of the formed image of the object, a correcting apparatus operative at least during exposure time for correcting the position of the image of the object in response to a detection output of the detecting apparatus so as to compensate the movement of the image of the object, a setting apparatus for setting exposure time, a calculating apparatus for calculating the amount of movement of the image of the object produced during exposure time based on the detection output of the detecting apparatus and the set exposure time, and a prohibiting apparatus for prohibiting the operation of the correcting apparatus when the amount of movement of the image of the object produced during exposure time is smaller than a predetermined value.

1. Field of the Invention
The present invention relates generally to cameras, and more particularly to a camera having a blurring correction apparatus for compensating a blurring of an image of an object to be photographed on a photographing plane.
2. Description of the Related Art
When a camera is moved by camera-shake or an object to be photographed moves, an image of the object on a photographing plane is blurred, resulting in an incorrect image. Thus, an apparatus for correcting the position of the image of the object to compensate and prevent this blurring has been conventionally proposed as disclosed in, for example, U.S. Pat. No. 4,788,596.
Depending on photographing conditions, the blurring correction is not always required or enabled. For example, no blurring correction is required in case of the small amount of blurring (the small amount of movement) which is produced during set exposure time. Furthermore, it is impossible to correct an excessively high speed blurring or an excessively large amount of blurring.
No consideration has been made for conventionally proposed apparatuses as to what control should be performed in such a photographing condition. Accordingly, the blurring correction sometimes causes such conventional apparatuses to consume useless energy despite a case where no correction is required. In addition, a photographer sometimes misunderstands that a photography is successful due to a sufficient blurring correction despite the fact that no sufficient correction is made.

Camera having blurring correction apparatus


The invention relates to a set-top box receiver allowing access to interactive digital TV coming from any IP-network. It makes use of the SAP/SDP protocols as a logic link between “classic” DVB services (satellite, terrestrial, cable) and IP services. The invention allows providing TV services relying on existing Internet architecture. Simulation means are provided, in the MHP middleware, for building an Event Information Table upon the SDP messages. Specific preview information is added to the SDP messages so that they can be linked to a DVB service.

The current DVB Digital television standard defines broadcast of audio, video and additional data on a stream. From this additional content, the interactive digital TV middleware MHP (Multimedia Home Platform) is able to extract several tables defined by the DVB SI (Section Information) standard relating to signaling information. Amongst these tables, the Event Information Table (EIT) contains data about the Events (the programs) broadcast on a specific Service (the channel). These data can then be browsed by means of specific software, called an Electronic Program Guide (EPG), which displays a list of Services (the channels) and their associated Events (the programs). However, the end-user is limited to browsing data coming from the stream only (that is a terrestrial, satellite or cable signal) and from no other source.
The DVB SI norm states that the EIT provides, amongst others, the name of the event, the start time of the event, the duration of the event, a locator, which is special information for the receiver (the Set Top Box or STB) to tune to the right Service.
Future developments of digital TV will probably provide several complementary sources linked to an Event: genuine DVB MPEG2 (Moving Picture Expert Group 2) streamed data (broadcast on a satellite, terrestrial or cable signal) and, for instance, an additional MPEG4 (Moving Picture Expert Group 4) preview stream coming from the Internet.
For such an application (MPEG4 preview stream coming from the Internet), the SDP/SAP protocols (Service Description Protocol/Service Announcement Protocol) seem to suit well, for they are designed to allow participation to multimedia conferences on the Internet. An end-user uses the SAP to register to an MPEG4 video announcer and is notified of the parameters of the video session thanks to the SDP. Therefore, the user needs several parameters, such as the name of the video, the start and end time of the video, the IP address of the MPEG4 video server and the number of the port on which the video is played.
Watching an SDP/SAP Internet-distributed MPEG4 preview of a broadcast MPEG2 Event would impose the merging of the SDP/SAP information (IP address and port) with the genuine DVB SI Event data, while complying with the DVB SI standard (and the EIT structure).

Transparent access of STB MHP digital TV middleware to IP video content


A color proofing foil of increased developability is provided which comprises a substantially transparent polymeric base sheet having a thin coating of a light sensitive composition on the surface of said sheet comprising a mixture of a colorant, a light sensitive material and an effective amount of anionic surfactant. The anionic surfactant is obtained by the reaction of P.sub.2 O.sub.5 with a condensation product of an alkylene oxide and an organic compound containing a reactive hydrogen. The light sensitive coating compositions of this invention when positive working exhibit greatly increased exposure speed. When negative working they exhibit increased development speed. In both cases, they retain the required good adhesion to film substrates, good scratch resistance, freedom from tack and acceptable resistance to overdevelopment.

The present invention relates to color proofing foils and refers more particularly to methods and materials for making color proofing foils of dark colors of improved developability from light sensitive materials.
U.S. Pat. No. 3,326,682 teaches that positive working color proofing foils can be prepared by coating o-quinone diazide photosensitizers and colorants, with or without resins and other additives, upon a transparent support, preferably polyethylene glycol terephthalate. In the practice of the above patent, the contents of which are explicitly made part of this application by reference, excellent color separation overlay proofing materials have been made from positive silver halide color separations used as exposure masks upon the appropriate colored proofing foil. After exposure and development in dilute aqueous alkali, the foils may be viewed individually and then placed one above the other on top of a white reflecting support to give a preview of the print which is to be made from plates from the aforementioned color separation silver halide positives.
A black coated foil is customarily used as one of the layers to add depth of color beyond that which would be obtained from a three color separation restricted solely to cyan, magenta and yellow. It has been found by experience that when a black dye or pigment is added to the foil coating composition, a great increase in required exposure results due to the absorption of light by the black dye or pigment. Dark colored foils, either black or other dark colors, similarly require undesirably increased exposure.
In the case of the black in positive systems, one approach to reduced exposure has been to reduce the level of dye or black pigment. This has the undesirable effect of giving a medium gray or light gray rather than deep, rich, black which would be preferred. These considerations also apply to other dark colors, which may be used apart from multicolor proofing processes in the graphic arts.
Still another approach to overcoming the exposure increase resulting from the full quantity of black dye or pigment is disclosed in U.S. Pat. No. 4,154,613. According to this invention, it was found that an overall exposure to light prior to or after imagewise exposure results in a highly desirable reduction of required imagewise exposure even though the dye or pigment level in the coating was at the desired level required for full, deep, rich colors. However, special equipment and an added process step is required.
A recent development in the technology of color proofing has been the introduction of automatic exposure and development machinery. With the use of such equipment, it is desirable that foils of all colors either deeply or lightly tinted have the same exposure speed and development characteristics, in order to avoid individual manual attention in processing. With the exception of the aforementioned technique of overall pre or postexposure, there has existed no convenient method of adjusting the exposure speed of the various differently colored proofing foils.
Therefore, one object of the present invention is to provide methods and materials for making color proofing foils which overcome the disadvantages of the prior art.
Another object is to provide novel light sensitive materials for making color proofing foils of increased light sensitivity.
Another object is to provide novel light sensitive materials for making color proofing foils in which exposure speed can be varied independently of the color selected.
Still another object is to provide foils of improved developability in which the required development time may be adjusted so that it is the same for all colors.

Light-sensitive color proofing film with surfactant in a light-sensitive coating


Method and apparatus for magnetically treating aqueous and non-aqueous liquid streams to enhance their flow properties and to reduce their tendency to deposit scales, encrustations and the like, wherein the liquid stream for treatment, either immediately prior to or substantially simultaneously with its traversal of a high density, magnetic flux field having a normal orientation with respect to the primary flow path of the liquid stream is deflected along secondary flow paths angularly displaced from the primary flow path causing in effect a high velocity, essentially shear angle traversal of the flux field by said stream. Apparatus therefor includes a plurality of permanent magnet groups arranged in parallel within a hollow casing or housing, each of said groups comprising a plurality of superposed, elongated magnets in registered, overlying relationship polarized along their longitudinal axis, the latter being parallel to the primary flow path, the adjacent magnet groups providing liquid passageways therebetween and generating magnetic flux paths essentially normal to the primary flow path.

1. Field of the Invention
The invention relates to the magnetic treatment of liquids and in particular to method and apparatus enabling the treatment of calcarious water and other aqueous and non-aqueous streams to enhance their flow properties and to reduce their corrosive effects on surfaces contacted by such streams.
Methods and associated apparatus for effectively reducing the tendency of calcarious water, for example, to deposit scales, encrustations and the like on heat exchange, conduit and other surfaces and based essentially upon the use of permanent magnets for the generation of magnetic fields to provide a magnetic treatment zone are described in the prior art in a variety of forms. In essence, the relevant techology requires, for beneficial treatment, that the contaminated water traverse one or more magnetic treatment zones, each being the locus of a high density magnetic flux, to yield a product water having reduced corrosive tendencies. The precise mechanism by which such beneficial effects obtain has not been definitely ascertained. In any event, it is hypothesized that the corrosive species present in the source water are, as a result of the the prescribed magnetic treatment, converted according to some chemical, electrochemical, physiochemical, etc., mechanism to an inert form non-injurious to conduit and process equipment surfaces. Theories thus far postulated range from the generation of induced polarization effects causing the formation of inert molecular complexes to the neutralization of the corrosive species by contact thereof with oppositely charged components in the water or with environmental surfaces. Thus, polarization and consequent orientation of the contaminants is said to increase their mobility and possible surface area within the aqueous medium correspondingly enhancing the likelihood of some form of neutralization reaction.
As will be recognized, the likelihood of scale formation in a particular instance is directly related to the residence time of the source, untreated water as well as the total water flow within a particular surface-contacting zone. For example, the recent emphasis on evaporative cooling principles with air cooled refrigeration systems e.g., home air conditioning units, has led to structural modifications wherein a water spray is directed onto the condenser coils. The amount of water used for such purposes is relatively small and thus the water flow over the condenser coils is minimal. Under such conditions, the deleterious effects of the corrosive species present in the water are most evident. Scale formation and the like severely reduce the efficiency of heat transfer across the affected surface correspondingly increasing unit energy requirements.
In view of escalating energy demands, the importance of making, for example, evaporative cooling systems feasible from both operational and economical standpoints is obvious.
Techniques heretofore promulgated for the magnetic treatment of calcarious water involve as an essential expedient the intersection of the calcarious water with a zone of high density magnetic flux. Approaches to the problem have focussed on such considerations as the water flow path relative to the flux field, flow path relative to the polar axes of the magnets as well as the type and orientation of permanent magnets to be used. As will be appreciated, numerous permutations within the scope of the aforedescribed variants may be efficacious as is evident from the prior art. Thus, flow parallel or normal to the polar axis of the magnets in conjunction with permanent magnets of the bar type polarized longitudinally or facially along their axes of symmetry are described. Whatever the arrangement, the primary objective of the magnetic treatment is to assure a thorough decontamination of the water to the fullest extent possible. In some instances, provision is made for multiple passage of the source water through the magnetic treatment zone. Representative here is U.S. Pat. No. 4,146,479 which describes a magnetic water conditioner wherein a plurality of coaxially arranged disc type magnets, polarized diametrically, are confined within a generally cylindrical sheath having outer, circumferentially spaced and radially extending rib portions, the longitudinally extending paths defined by such ribs defining, in conjunction with a casing of high permeance for the assembly, the annular passageways as well as zones of magnetic treatment. Source water is caused to traverse each of the annular passageways prior to exiting the device.
In general, prior art methods for magnetically treating calcarious water require relatively complex and expensive structural modifications of existing facilities for their effective implementation. Moreover, optimum effects may require the use of more than one unit and/or the use of yet additional features to achieve, for example, the advantage of increased water velocity through the magnetic treatment zone.
In accordance with the discovery forming the basis of the present invention, it has been ascertained that the beneficial effects of the magnetic treatment can be enhanced significantly by relatively simple means embodying a principle practicably applicable to conditioners currently available commercially with a minimum of structural modification, or in the form of a unitary device useful as an effective alternative or adjunct to known magnetic conditioners.
Thus, a primary object of the invention is to provide method and apparatus for the magnetic treatment of calcarious water and other liquid streams wherein the foregoing and related disadvantages are eliminated or at least mitigated to a substantial extent.
Another object of the invention is to provide method and apparatus capable of effectively reducing the tendency of calcarious water and other liquid streams to deposit scales, encrustations and other foulants on conduits, process equipment and other surfaces contacting the flowpath of such water as well as to enhance the flow properties of such streams.
Yet another object of the invention is to provide such method and apparatus capable of simple implementation with existing facilities and wherein requirements for structural modification are minimized.
Still another object of the invention is to provide such method and apparatus capable of effective use either in conjunction with or as an alternative to known magnetic water conditioning treatments.
A further object of the invention is to provide such an apparatus capable of simple and economical manufacture from materials readily available commercially.
Other objects and advantages of the invention will become apparent hereinafter as the description proceeds.
Attainment of the foregoing and related objects is made possible in accordance with the invention which, in its broader aspects, includes a method for treating aqueous and non-aqueous liquid streams to enhance their flow properties and to reduce their tendency to deposit scales, encrustatations and the like, comprising directing said stream along a primary flowpath to contact and traverse a high density magnetic flux field having a directional orientation, i.e., flux or polar axis, substantially normal to said primary flow path and wherein said stream, either immediately prior to or substantially simultaneously with its contacting said flux field, contacts deflecting means for directing said stream along secondary flow paths angularly displaced from said primary flow path or direction thereby causing an essentially shear angle traversal of said flux field by said stream.
In a further aspect, the invention includes apparatus for such a method comprising an enclosure having inlet means for admitting a liquid stream to said enclosure, means for directing said inlet stream along a primary flow path terminating in outlet means for discharging said stream from said enclosure, permanent magnet means for generating a magnetic flux field traversing said primary flow path and having a flux or polar axis oriented substantially normal to said primary flow path, deflecting means positioned in said primary flow path for directing said stream through said flux field along secondary flow paths angularly displaced from the direction of said primary flow, and outlet means for discharging said stream from said enclosure.
In yet a further aspect, the invention includes the contacting of aqueous streams subsequent to completion of the magnetic treatment with anode means.
The invention is explained by reference to the accompanying drawings wherein:


An inductance change detection circuit for detecting a change in inductance with a simple circuit design, having a series circuit having a resistor and a coil of which an inductance changes according to a position of an object; a pulse power supply 1 for applying a pulse voltage to the series circuit; a first signal generator for generating a first signal when an output voltage of the resistor in the series circuit becomes a specific voltage level; a second signal generator for generating a second signal responsive to a pulse voltage of the pulse power supply; and a comparison pulse generator for generating a pulse signal having a duty ratio responsive to the coil inductance based on the first signal and second signal.

1. Field of the Invention
The present invention relates to an inductance change detection circuit for detecting a change in the inductance of a coil. More specifically, the invention relates to an inductance change detection circuit for detecting a change in the position of an object based on a change in the inductance of a coil due to a change of a magnetic flux.
2. Description of the Related Art
A change in the position of an object that disrupts or indirectly changes the magnetic flux of a coil when the position of the object changes also results in a change in the inductance of the coil. It is therefore possible to detect a change in the object's position by detecting this inductance change as a DC signal, and devices used for this purpose are known from the literature. It is particularly desirable for such devices to detect this inductance change as a DC signal using a simple circuit design.
FIG. 8 shows a typical inductance change detection circuit according to the prior art as taught in Japanese Patent Laid-Open Publication No. 7-332910. FIG. 8A is a circuit diagram of this inductance change detection circuit, and FIG. 8B is a graph illustrating relationship between output pulses from a pulse power supply, and the output waveforms from a resistor R.sub.F in the inductance change detection circuit. Shown in FIG. 8A are a coil L of which the inductance changes according to the position of an object; a resistor R.sub.F having one end connected in series with the coil L and the other end to ground; and a pulse power supply 101.
The inductance change detection circuit shown in FIG. 8A detects the output from the output terminal, that is, the voltage between the resistor R.sub.F and ground, as an output voltage. When the position of the detected object has not changed from an initial position (referred to as the reference position below), this output voltage has a waveform as indicated by a solid line in FIG. 8B. When the position changes, however, the coil inductance L also changes, and the output voltage waveform changes as indicated by a dotted line in FIG. 8B. Because the output wave thus changes before and after the object changes position, it is possible to measure the voltage V.sub.0 and V.sub.01 at a specific time t.sub.k, and to detect the inductance change from this voltage difference.
A typical inductance change detection circuit of this type, however, has difficulty in detecting an inductance change with good precision when the signal amplitude from the output terminal drops or varies, however, because the change in coil inductance is detected from output voltage values detected at specific discrete points in time.
There is therefore a need for an inductance change detection circuit whereby a change in coil inductance can be detected with good precision using a simple circuit configuration.


An embodiment of a method for network resource management comprises performing joint traffic engineering and physical layer power control on a controller and using a routing and power control optimization process that comprises a combined alternating direction method of multipliers (ADMM) process and a power management process. First and second commands are generated at the controller according to optimization parameters determined by the routing and power control optimization process. The first and second commands are transmitted from the controller to nodes connected to the controller. The first commands are for modifying transmission parameters for links between nodes and the second commands are for modifying transmission parameters for connections between nodes and user devices.

A cellular radio system provides communications coverage over a selected area by a radio service and is divided into cells serviced by one or more antennas for corresponding radio base stations. Communications, for example, for data or voice transmissions, are generally provided over a wired backhaul network that is serviced by one or more network routers. The network routers are used to route the communications between origination points such as user handsets, other networks, service providers, or the like and the base stations, where the base stations transmit the communications wirelessly to end user devices.

System and method for joint power allocation and routing for software defined networks


A system for reporting a condition of a first entity to a second entity, the system includes a processor that executes instructions to determine the condition of the first entity based on an aggregation of structured and unstructured information and entity-activity information of the first entity, and a reporting unit that reports the condition of the first entity to the second entity.

1. Field of the Invention
The present invention generally relates to a method and apparatus for reporting a condition, and more particularly to system, method, and computer program product for reporting a condition of a first entity to a second entity.
2. Description of the Related Art
Typical reporting systems simply attempt to contact a person that is or is believed to be directly affected by a situation, event, hazard, occurrence, etc. In some typical systems, if for example, a person needs help as a result of the situation, the system can attempt to contact another person in order to provide aid to the person in need. These systems may also allow the person who is believed to be directly affected by the situation to be made aware of their plight. In other situations, a single designated party is contacted in case of an emergency or accident—examples include health care proxies, emergency contacts listed in health care forms, motor vehicle registration forms, etc.
These conventional technologies, however, fail to consider third parties or other close parties who may be concerned about the person's well-being. Given the vast amount of structured and unstructured information that is available today, others, who are aware (or believe they are aware) of a location of the person, may be concerned if they become aware of an event near the area where the person is (or is believed to be) located. For example, structured information is widely available through, police reports, accident reports, weather reports, road condition reports, etc. In addition to the above-mentioned structured information, unstructured information is also available through news reports on the internet, including photos and videos, radio and media broadcasts, along with other unstructured information, such as, for example, blogs, posts, tweets, updates, media postings, at a number social networking sites.
As a result of this widely available information, those who are concerned for the well-being of the person may become concerned for the well being of the person or entity whose condition is believed to be affected. However, those who are concerned have to resort to conventional technology in order to ease their concerns. For example, they may try to contact the person to inquire about their condition or they may have to wait for that person to contact them. Similarly, they may have to wait until they become aware of information regarding the condition of the person from a source other than the person, e.g., a news report, a social media posting, a health care worker, etc.
That is, before a concerned party relying on conventional technologies is able to confirm the person's condition, they may be required actually make contact with the person or wait until they receive additional information regarding that person's condition. As a result, the concerned party may have to wait for a substantial amount of time before they are able to ascertain the condition of the person and before they are able to ascertain whether or not the person has even been affected by the situation or event. In addition, it may be too late to take additional action or provide help to the affected person with the current mechanisms.
Accordingly, there is a need for an improved system and method of reporting a condition of a first entity to a second entity.

Systems, methods, and computer program products for reporting condition of first entity to second entity

International Business Machines Corporation


A fuel manifold adapted to communicate with at least one fuel tank of an aircraft is presented. The manifold defines an enclosure adapted to be filled with fuel and to have an internal pressure P1 higher than the internal pressure P2 of the fuel tank. The enclosure includes at least one ceiling and at least one side wall provided with overflow holes adapted to communicate with the fuel tank. The manifold includes a mechanism for discharging an air pocket, trapped between the ceiling and the level of the overflow holes, to the fuel tank.

In the aeronautics field, the regulations in force, such as certifications FAR25.981.b and CS25.981.b, or their equivalents, impose flammability constraints for the fuel contained in aircraft tanks.
In practice, the airframe manufacturer must either be able to prove that the fuel is below these flammability constraints, or establish means for reducing explosion risks.
The use of inerting systems is well known for the generation of an inert gas, such as nitrogen or any other inert gas such as carbon dioxide, and introducing said inert gas into fuel tanks in order to reduce the risk of explosion from said tanks. This solution is widely used for tanks having a large air pocket, i.e., tanks contained in the wings of the aircraft or the central tanks primarily contained in the fuselage of the aircraft.
However, it is difficult to prove compliance with the regulations in force for a fuel manifold whose primary function is to be filled with fuel to be kept constantly full in order to avoid unpriming of the supply pumps of the aircraft engine.
The manifold is intended to communicate with at least one fuel tank. FIG. 1, which schematically shows a manifold (1) according to the prior art, defines an enclosure (2) intended to be filled with fuel and to have an internal pressure P1 higher than the internal pressure P2 of the fuel tank. The enclosure (2) comprises at least one ceiling (3) and at least one side wall (4a) connected to one another so as to define at least one zone (5) between them wherein at least one air pocket (6) can be trapped. The manifold comprises overflow holes (7) arranged in the side wall (4a) near said entrapment zone (5) and intended to communicate with the fuel tank.
According to the state of the art, the overflow holes do not make it possible to discharge the trapped air pocket because structural constraints do not make it possible to position the overflow holes flush with the upper ceiling of the manifold. Furthermore, other air pockets can be trapped, in particular when the filling system of the manifold is not working and/or during particular pitch and/or roll phases.
The manifold is constantly full of fuel, such that the air pocket inside the manifold is relatively small, which limits, or even prevents any injection of inerting gas inside the manifold.
Injecting inerting gas in the manifold also cannot be considered, as it would cause an overpressure of the manifold and the fuel tank in communication therewith, the appearance of bubbles and foam that could harm the operation of the pumps situated in the tank, and an uncontrolled transfer of fuel through the overflow holes.
Moreover, it is that much more difficult to ensure compliance of the manifold with the standard in force, since it is not directly connected to an inert tank, especially if fuel degassing issues are taken into account.
In the current state of the art, to bring the manifold into compliance with the standards in force, a first solution consists in pressurizing the manifold relative to the atmospheric pressure so as to shift the flammability envelope of the fuel. However, pressurization exposes the manifold to greater structural stresses, having a significant impact on the mechanical strength of the aircraft and its operating safety. Furthermore, it is difficult to be precise in estimating this physical phenomenon with respect to the flammability of the fuel.
Another solution consists in injecting inerting gas into the fuel tank that is in communication with the manifold and considering that if the fuel tank meets the requirements of the standards in force, the manifold meets them as well. This solution is based entirely on a qualitative argument, and it is difficult to prove its effectiveness if, as mentioned above, one considers the degassing of the fuel in the manifold. Furthermore, if the fuel tank in communication does not require inerting, this solution does not work.
Another solution consists in coating some inner walls of the manifold with a foam able to prevent the spread of flames in case of ignition of the fuel and to suffocate the fire. However, aside from decreasing the working volume of the manifold, the foam absorbs a quantity of fuel that cannot be retrieved, thereby decreasing the autonomy of the aircraft. Furthermore, the foam can break down and be aspirated by the supply means of the engine. Lastly, static electricity may appear within the foam, giving rise to an ignition risk.


A therapeutic device for treating tendinitis and epicondylitis of the elbow is provided. The device comprises a loop of elastic material, wherein the loop has a 360-degree twist built therein so as to provide distinct first and second surfaces on the loop. The device is employed by positioning the loop about the elbow joint in a figure-8 formation, such that the loop is divided into an upper-band and a lower-band. The upper-band encircles the arm above and adjacent the elbow joint, the lower-band encircles the arm below and adjacent the elbow joint. The user then permits the loop to remain positioned about the elbow joint for a period sufficient to provide the desired relief.

1. Field of the Invention
The present invention pertains to a therapeutic device for the elbow joint, as well as a therapeutic method utilizing this device. More specifically, this device alleviates the discomfort associated with tendinitis and epicondylitis of the elbow by providing gentle pressure around the circumference of the elbow both above and below the joint.
2. Description of the Prior Art
Athletes participating in a variety of sports including tennis, other racket sports, baseball, golf and weight lifting, to name but a few, often experience discomfort in and around the elbow joint. Many of these ailments can be directly attributed to frequent rotation of the elbow, particularly when the arm is fully extended. Thus, while participants in racket sports are especially prone to such problems, even the continued use of hand-tools may cause similar discomfort.
Often the discomfort experienced is attributed to "tennis elbow," a term which is loosely employed to describe a number of different elbow complaints. Primarily, however, the term is used to describe lateral or medial epicondylitis or tendinitis of the associated tendons in the region. In the elbow joint, the flexor muscle of the forearm connects to the medial epicondyle (inside elbow protrusion of the humerus), and the extensor muscle connects to the lateral epicondyle (outside elbow protrusion of the humerus). These muscles are connected by tendons to the respective epicondyles of the humerus. Excessive tension in the flexor and extensor muscles (such as that caused by the activities describes previously) puts tremendous stress on the connection between the tendons and the epicondyles. The result can be inflammation of the epicondyles, also known as epicondylitis. Alternatively, or simultaneously, the tendons themselves may become inflamed, particularly if the tendon begins to pull away from the bone. This inflammation of the tendons is termed tendinitis.
As is often the case with overuse or repetitive-stress injuries, foregoing the activity which caused the tendinitis or epicondylitis in the elbow is usually the most effective treatment. Patients, however, are often unwilling to forego the offending activity for an extended period of time. Thus, numerous devices have been developed in an attempt to reduce the stress on the elbow joint which occurs during exercise. For example, U.S. Pat. No. 3,789,842 describes a therapeutic support device comprising a flexible, but non-elastic band which is secured about the forearm adjacent to the elbow. The band is tightly secured about the forearm, and, because of its non-elastic nature, resists the expansion of the forearm muscles. A similar device is shown in U.S. Pat. No. 3,877,426.
While these prior art devices will often lessen discomfort when used during the offending activity (i.e., tennis), none are designed to reduce stress in the tendon/epicondyle area during the recuperative period which leads to healing. In addition, many of these devices are rather bulky and apply a considerable amount of compression about the forearm, and are thus not suitable for continual use. Thus, there is a need for a therapeutic device which will continually reduce the stress on the tendon/epicondyle area of the elbow, and which may be worn for long periods of time without discomfort.