nimum Reserved Traffic Rate, Maximum Latency, Tolerated Jitter, Uplink Grant Scheduling Type, SDU size for fixed length SDU service flows, Request/Transmission Policy, and Unsolicited Grant Interval. If present, the Minimum Reserved Traffic Rate parameter has the same value as the Maximum Sustained Traffic Rate parameter. Real-Time Polling Service (rtPS) is designed to support real-time UL service flows that transport variable-size data packets on a periodic basis such as Moving Pictures Experts Group (MPEG) video format. This service offers real-time, periodic, and unicast request opportunities, which meet the service flow's real-time requirements and further allow the MS to specify the size of the desired grant. This service involves more overhead than UGS, but supports variable-sized grants for optimal data transport. The BS provides periodic unicast request opportunities. In order to ensure proper operation, the Request/Transmission Policy is set such that the MS is prohibited from using any contention-based request opportunities for this connection. The BS may render unicast request opportunities as prescribed by this class even if prior requests were not fulfilled. As a result, the 6.6 IEEE 802. 16m QoS classes MS uses only unicast request and data transmission opportunities in order to obtain UL transmission grants. The mandatory QoS parameters corresponding to this class are Minimum Reserved Traffic Rate, Maximum Sustained Traffic Rate, Maximum Latency, Uplink Grant Scheduling Type, Request/ Transmission Policy, and Unsolicited Polling Interval. Extended Real-Time Polling Service (ertPS) is a scheduling mechanism which utilizes the advantages of UGS and rtPS. The BS provides unicast grants in an unsolicited manner similar to UGS, reducing the latency of bandwidth request. Unlike the UGS allocations, the ertPS allocations are variable-sized. The BS may provide periodic UL allocations that are used for requesting the bandwidth as well as for data transmission. By default, the size of allocations corresponds