An efficient channel access method using polling and dynamic priority assignment

摘要

In this paper we consider multi-access communication problem to allocate the channel efficiently among different nodes which wants to use it for communication. The problem is interesting for the access point does not know the number of packets to be transmitted per user node and nodes also don't know packet distribution at other nodes. There are many interesting approaches to this problem [1]. Broadly, we can classify as random access approach and deterministic approaches. In the random access approach each node tries to get hold of the channel as soon as it has a packet to transmit. Due to lack of knowledge about other nodes and no prior coordination among nodes such a method may lead to colliding packets over the channel. Deterministic methods involve scheduling of transmission based on some properties. Here, we introduce a new channel access method. This method follows deterministic model for transmitting packets. In this scheme the access point collects and schedules transmission of data packets in an efficient way. The receiver for which maximum packets are generated is given preference. However, such preferences can be changed if needed. Using simulation we find limits on the number of packets generated, number of packets lost and number of packets successfully transmitted with respect to receiver and channel capacity. This technique is compared with existing wireless protocol CSMA/CA. Our simulation results indicate that this scheme can work more efficiently than CSMA/CA with respect to channel throughput. The scheme is also compared with the conventional polling technique and the results capture the fact that the channel throughput of the proposed method is better than conventional polling at low load and the delay per node is nearly constant in proposed method while it increases in polling method. The results show that the proposed method shares the channel efficiently at low as well as the high load.