nd Differentiated Services (Diffserv). These models encompass several categories of mechanisms that provide preferential treatment to specified traffic. A service class defines how each QoS parameter is applied to a specific service. Table 6-6 provides the typical service classes and their characteristics. 6.5.1 Legacy QoS Classes The IEEE 802.16-2009 standard defines several Quality of Service-related concepts, including service flow QoS scheduling, dynamic service establishment, and two-phase activation model [1]. The requirements for QoS function include the following: 1. A configuration and registration function for pre-configuring MS-based QoS service flows and traffic parameters; 2. A signaling function for dynamically establishing QoS-enabled service flows and traffic parameters; 3. Utilization of MAC scheduling and QoS traffic parameters for UL service flows; Table 6-6 Characteristics of Service Classes [11] Delay Bit Error Rate Service Class Categories Requirement Bit Rate (BER) Margin Use Cases Point-to-multi-point; multi-point-to- <20 ms 1-20 Mbps 10-9 < BER < 10-6 Tele-presence/video-conference; multi-point; multi-point-to-point; collaborative work navigation systems; highly interactive real-time gaming; real-time video streaming Asymmetric; interactive; low rate 20-100 ms 8-512 kbps 10-9 BER < 10-6 Remote control sensors; interactive geographical maps Point to multi-point; multi-point to 20-100 ms 1-50 Mbps 10-6 < BER < 10-3 Rich data call; video broadcasting/ multi-point; multi-point to point; streaming; high quality video interactive; high rate conferencing; collaborative work Conversational; soft BER 100-200 ms 8-512 kbps BER < 10-Superscript(3) Voice telephony; instant messages; multiplayer gaming; audio streaming; video telephony (medium quality); multiplayer gaming (high quality) Conversational; symmetric QoS; 100-200 ms 1-50 Mbps High quality video telephony; tight BER collaborative work; access to databases; file systems Point-to-point unidirectional (uplink >200 ms 8 kbps- 50 BER < 10-6 Mess