Group-Based Uplink OFDMA Random Access Algorithm for Next-Generation WLANs

下一代WLAN中一种基于分组的上行OFDMA随机接入方法

School of Electronics and Information, Northwestern Polytechnical University, Xi'an 710072, China

Received: 15 March 2019

Abstract

The traditional wireless local area network(WLAN) standard, IEEE 802.11, adopts carrier sense multiple access/collision avoidance(CSMA/CA) mechanism to allow a single user to compete for channel access. The upcoming WLAN standard, IEEE 802.11ax, combines orthogonal frequency division multiple access(OFDMA) technology with random access, and use Uplink OFDMA Random Access(UORA) technology as uplink random access. Therefore, UORA which allow multiple users to access channel at the same time can improve the utilization of network resources. Although UORA technology in IEEE 802.11ax has the advantage of low signaling overhead, when the number of users of network is large, the increase of random access collisions will lead to the decrease of network throughput. Therefore, we propose a group-based UORA method. As a central scheduling node, Access Point(AP) divide Stations(STAs) and resources to groups and sets different GroupID for different groups. STAs can only access resources with the same GroupID randomly. The validity of group-based UORA method is verified by mathematical model analysis and simulation. The network throughput of our group-based UORA is higher than that of the original UORA in IEEE 802.11ax, so it has great practical significance.

摘要

传统的无线局域网（wireless local area network，WLAN）标准IEEE 802.11采用载波侦听/冲突避免机制，允许单个用户竞争信道接入。而即将到来的下一代WLAN标准IEEE 802.11ax，将正交频分多址（orthogonal frequency division multiple access，OFDMA）技术和随机接入相结合，在上行传输中可以采用上行OFDMA随机接入（uplink OFDMA random access，UORA）技术，允许多个用户同时随机接入信道传输数据，因此提高了网络的资源利用率。虽然IEEE 802.11ax中的UORA技术具有信令开销小的优点，但是当用户数较多的时候，随机接入的冲突增加会导致网络吞吐量下降。因此，提出一种分组UORA的接入方法，无线接入点（access point，AP）作为中心调度节点对用户和资源进行分组，为不同组的用户和资源设置不同的标签，用户只能随机接入具有相同标签的资源。通过建立数学模型和仿真的方法，验证了分组UORA方法的有效性。分组UORA方法的网络吞吐量较IEEE 802.11ax中的原始UORA有所提升，因此具有一定的实际意义。