er-cell/sector interference effects. The procedures include MAC layer functions (e.g., interference measurement/assessment reports sent via MAC signaling and interference mitigation by scheduling and flexible frequency reuse), and PHY functions (e.g., transmit power control, interference randomization, interference cancellation, interference measurement, transmit beamforming/precoding). The inter-BS coordination functions coordinate the operation of multiple base stations by exchanging information, about interference statistics between the base stations via core-network signaling. 3.2.1 Data-Plane and Control-Plane Functions in Base Stations and Mobile Stations Figure 3-14 shows the user data processing path at the BS and MS. As shown in the figure, the user data traverses the path from network layer to physical layer and vice versa. In the transmitter side, a network layer packet is processed by the convergence sub-layer, the ARQ function (if enabled), the fragmentation/packing function, and the MAC PDU formation function, to form the MAC PDU to be sent to the physical layer for processing. In the receiver side, a physical layer SDU is processed by MAC PDU formation function, the fragmentation/packing function, CHAPTER 3 IEEE 802.16m Reference Model and Protocol Structure Network Layer Management SAP and Control SAP Radio Resource Control and Management (RRCM) CS SAP Relay Radio Resource Location System Convergence Sublayer Configuration Functions Management Management Management Service Flow Mobility Idle Mode Classification Multi-Carrier E-MBS Management Management Header Service flow and Suppression Network-entry Security Self Organization Connection Management Management Management MAC SAP Scheduling and Resource Multiplexing Fragmentation/Packing Multi Radio Sleep Mode Coexistence Management PHYControl MAC PDU Formation Data Forwarding Interference Link Adaptation Control Management Ranging (CQI, HARQ, power Signaling control) Encryption HARQ/CQI Medium Access Control (MAC) Ranging Feedback PHY SAP PHY Prot