lation CS SAP IEEE 802.16 GPCS MAC SAP 802.16m Protocol IEEE 802.16m MAC CPS and Security Sublayer Layers PHY SAP IEEE 802.16m PHY FIGURE 5-8 GPCS protocol layering model [1] a broadcast port [11]. The PHS algorithm defines rules for how packets with suppressed fields are reconstructed, based on the PHSI and the associated PHS rule. This reconstruction method can also be applied on packets transferred over the GPCS. The GPCS protocol layering model is shown in Figure 5-8. The GPCS uses the GPCS SAP, an instance of the logical CS SAP. The GPCS SAP parameters enable the upper layer protocols to generically pass information to the GPCS SO that the GPCS does not need to interpret upper layer protocol headers in order to map the upper layer data packets into proper IEEE 802.16m MAC connections. Since the SAP parameters are explicit, the parsing portion of the classification process is the responsibility of the upper layer. The parameters are relevant for SAP data path primitives, GPCS_DATA. request, and GPCS_DATA.indication as described in reference [1]. The parameters SFID, MS MAC Address, STID (for mobile and base stations compliant with IEEE 802.16m), FID (for mobile and base stations compliant with IEEE 802.16m), length, and data are described in reference [12]. Note that SFID and MS MAC Address are not transferred over the IEEE 802.16 air interface. The GPCS maps the CID or STID+ FID to SFID and MS MAC Address, and then passes them to the upper layer of the GPCS through GPCS_DATA.indication, where the CID or STID+FID are provided in MAC SAP. 5.5 THE 3GPP LTE PACKET DATA CONVERGENCE PROTOCOL The 3GPP Packet Data Convergence Protocol is part of Layer 2 protocols that provide the following services and functions to other protocol layers in the user-plane [20]: Header compression and decompression using ROHC; Transfer of user data; In-sequence delivery of upper layer PDUs at PDCP re-establishment procedure for RLC AM; 5.5 The 3GPP LTE packet data convergence protocol Duplicate detection of lower layer SDUs at PDCP re