each transport block (TB), * thus allowing for receiver-side detection of residual A transport block is defined as the data accepted by the physical layer to be jointly encoded. © 2009 by Taylor & Francis Group, LLC Radio-Interface Physical Layer Table 3.1 LTE Physical Channels Channel Direction Description Downlink PDSCH Physical downlink Carries downlink user data from shared channel upper layers as well as paging signaling Physical multicast Used to support point-to- channel multipoint multimedia broadcast multicast service (MBMS) traffic Physical broadcast Used to broadcast a certain set of channel cell or system-specific information PCFICH Physical control Determines the number of OFDM format indicator symbols used for the allocation channel of control channels (PDCCH) in a subframe PDCCH Physical downlink Carries scheduling assignments, control channel uplink grants, and other control information; the PDCCH is mapped onto resource elements in up to the first three OFDM symbols in the first slot of a subframe PHICH Physical HARQ Carries the hybrid automatic indicator channel repeat request (HARQ) ACK/NAK Uplink PUSCH Physical uplink Carries uplink user data from shared channel upper layers; resources for the PUSCH are allocated on a subframe basis by the scheduler PUCCH Physical uplink PUCCH carries uplink control control channel information, including channel quality indication (CQI), HARQ ACK/NACK, and uplink scheduling requests PRACH Physical random Used to request a connection access channel setup in the uplink © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology Frame (10 ms) Subframe #0: Demodulation reference signals PUSCH, PUCCH Figure 3.5 Uplink radio frame structure. errors in the decoded TB. The corresponding error indication, reported via uplink, can be used by the downlink hybrid automatic repeat request (HARQ) protocol to perform a retransmission. Channel coding. The goal of this process is to increase reliability in the transmission by adding redund