ta processing path, such as service flow classification and header compression, as well as MAC and PHY data packet processing and encryption functions. As shown in Figure 3-8, the IEEE 802.16m data-plane entity comprises the service specific Convergence Sub-layer, IEEE 802.16m Data-Plane Entity CS SAP Service Specific Convergence Sublayer MAC SAP Medium Access Control Functional Group (Data Plane Functions) Security Sublayer (Data Plane Security) PHY SAP Physical Layer (PHY) FIGURE 3-8 The IEEE 802.16m data-plane entity [12] CHAPTER 3 IEEE 802. 16m Reference Model and Protocol Structure MAC functional group, security, and physical layer protocols corresponding to data-plane user packet processing. The MAC and PHY SAPs, while conceptually the same as those specified by IEEE 802.16- 2009 standard, have different manifestation due to the new and/or modified MAC and PHY features introduced in the IEEE 802.16m standard. There is no significant change in CS SAP relative to that specified in the IEEE 802.16-2009 standard [3]. The CS provides a mapping of external network data formats (e.g., IP layer packets, ATM cells) received through CS SAP into MAC SDUs that are delivered to the MAC CPS via MAC SAP. This includes classifying external network SDUs and associating them with a proper Service Flow Identifier and Connection Identifier. A Service Flow (SF) is a MAC transport service that provides unidirectional transport of packets in the downlink or uplink [14]. It is identified by a 32-bit SFID. A service flow is characterized by a set of QoS parameters, i.e., a parameter set associated with a service flow identifier containing traffic parameters which define scheduling behavior of uplink or downlink service flows associated with transport connections. An admitted and active service flow is uniquely mapped to a CID. Note that the IEEE 802.16 standard supports two phase activation model. i.e., the resources for a service are first admitted or reserved and once the BS and MS negotiations are completed, the resources are ac