پيشنهاد يك پروتكل LLC وابسته به كانال راديويي در GPRS و ارزيابي بهره وري آن در ترافيك اينترنت

The Global System for Mobile Communications (GSM) Phase 2+ specifies a type of packet data service called General Packet Radio Service (GPRS). GPRS allows dynamic bandwidth allocation in which channels are allocated to a Mobile Station based on its demand. These results in better resource utilization compared to the circuit-based data services. In general, packet-based communication has a more bursty traffic and a longer connection time than circuit-based. A communication session may last for an extended period of time with intermittent packet transmissions. This traffic behavior coupled with flexible bandwidth allocation in a GPRS network results in multiplexing gain over the circuit switched data networks. This paper investigates the throughput and buffer utilization in a GPRS network under popular Internet traffic models, such as WWW suppose the (Logical Link Control) LLC and (Radio Link ControllMedium Access Control) RLC/MAC layers in GPRS. The layers are considered to work either in acknowledged or non-acknowledged mode. A new protocol for the acknowledged mode of LLC layer, "channel dependent LLC protocol", is proposed. This protocol dynamically takes in to consideration the quality of wireless channel. When the quality is good, the transmission is allowed. On the other hand when the channel condition deteriorates, the transmission can not take place.