Queue-Based MAC Protocol with Subcarrier Allocation Optimization

摘要

A MAC protocol, useful for WLANs, is provided for random access over a channel. The protocol includes three concurrent processes. The channel includes a contention subchannel and a transmission subchannel. In the contention process, all nodes use the standard RTS/CTS mechanism operated on the contention subchannel to contend for a transmission right. When one node gains the right, all the nodes store the contention result into their respective contention queue (CQ) buffers. In the transmission process, the nodes sequentially transmit their data over the transmission subchannel according to the order of the nodes stored in the CQ buffers. When one node finishes transmission, the CQ buffers are updated. The contention and transmission processes are connected by the queuing process for dynamically updating each node's CQ buffer. When OFDM is used in a random-access system, numbers of data subcarriers in both subchannels for maximizing the system throughput are given.

主权项

1. A method for enabling a plurality of nodes to communicate with an access point (AP) over a multiple-access channel, the channel including a contention subchannel and a transmission subchannel both of which are separate from each other, each of the nodes having a node identity (ID) for identification, each of the AP and the nodes having an individual contention queue (CQ) buffer for storing a waiting queue of the node IDs of the nodes each already granted with a right of data transmission by the AP, the method comprising:
when a first node being one of the nodes has data to be sent to the AP, contending, by the first node, for the right of data transmission until the AP grants the right of data transmission to the first node, wherein the first node contends for the right by communicating with the AP on the contention subchannel; when the AP grants the right to the first node, enqueuing, by each of the AP and the nodes, the CQ buffer thereof with the node ID of the first node; when the node ID of the first node in the waiting queue of the first node's CQ buffer has a position such that the first node is permitted to send out the data thereof to the AP, transmitting, by the first node, the data of the first node to the AP over the transmission channel; and when data transmission from the first node to the AP completes, dequeuing, by each of the AP and the nodes, from the CQ buffer thereof the node ID of the first node.