 there are N pairs in the group, the number of bits per pair is equal to [log2N]. The third bitmap is the Resource Allocation Bitmap which uses N bits per MS to signal the HARQ burst size and resource size for the scheduled MS in the subframe or extended subframe that are scheduled in the frame. The scheduled mobile stations may have a different number of bits in the third bitmap when they are assigned different MIMO mode and number of streams. 6.11 BANDWIDTH REQUEST AND ALLOCATION Bandwidth Request (BR) refers to a mechanism that a mobile station uses to inform the serving BS about the need for UL bandwidth allocation. The MS may use a contention-based random access BR indicator and an optional quick access message on BR channel, a standalone bandwidth request, a piggybacked bandwidth request carried in an extended header in the MAC PDU, or a bandwidth request using fast-feedback channel. Bandwidth requests in standalone and piggybacked schemes are made in the form of the number of bytes needed to carry the MAC PDU, excluding the physical layer 6.11 Bandwidth request and allocation overhead. The bandwidth request message from the MS indicates the size of the payload excluding any header, security, or other MAC PDU overhead that are included during transmission over the air interface. An MS requests UL bandwidth on a per-connection basis. In addition, the MS may request bandwidth for multiple connections in a piggyback scheme. Two mechanisms may be used by a network operator to impose cell access restrictions. The first mechanism is an indication of cell status and special reservations for control of cell selection and reselection. The second mechanism, referred to as access class control, prevents selected classes of users from sending initial access messages for control of emergency calls. The serving BS may advertise a minimum access class in the BR channel configuration within a DL control message. When an MS has data to send in the uplink using the contention-based random access bandwidth request mechanism, 