Abstract:

Concerning the high overheads of current channel access mechanisms and frequent collisions in high-density deployed Wireless Local Area Network (WLAN), an enhanced mechanism named as Hybrid Frequency-domain Channel Contention (HFCC) based on frequency-domain channel contention was proposed. Firstly, the subcarriers within Orthogonal Frequency Division Multiplexing (OFDM) symbols which were used for frequency-domain channel contention were classified as contention subcarriers and information subcarriers. Secondly, two rounds of channel contention were performed when station (STA) needs to access channel and the confirmation of successful channel contention was performed if necessary. Finally, a single OFDM symbol was used to acknowledge correct reception of a packet. The theoretical analysis showed that, compared with Distributed Coordination Function (DCF), when many STAs (35 or so) were contending a channel in the network, the collision probability of HFCC declined 99.1%, and the system throughput of it increased 73.2%. In addition, the throughput of HFCC respectively increased by 35.7% and 75.2% compared with Back2F and REPICK. The analysis results show that HFCC can reduce the overhead while improving the robustness, which is suitable for high-density deployed network.

Key words: Wireless Local Area Network (WLAN), Distributed Coordination Function (DCF), frequency domain, channel contention, high-density deployment

摘要：

针对现有无线局域网信道接入机制开销较大、高密部署场景下站点碰撞频繁的问题,提出一种基于频域竞争的改进机制混合频域竞争(HFCC)。首先,将用于频域竞争的正交频分复用(OFDM)符号中的子载波分类为竞争子载波和信息子载波;其次,每次信道接入均采用两轮信道竞争,必要时开启成功竞争信道确认;最后,利用单个OFDM符号反馈数据正确接收信息。理论分析表明,当网络中竞争站点(STA)较多(35个左右)时,与分布式协调功能(DCF)相比,HFCC站点碰撞概率下降幅度和系统吞吐量提升幅度分别为99.1%和73.2%;与现有频域竞争机制Back2F和REPICK相比,系统吞吐量分别提高了35.7%和75.2%。分析结果表明,HFCC可在降低开销的同时提高系统的强健性,适用于高密部署场景。

关键词: 无线局域网, 分布式协调功能, 频域, 信道竞争, 高密部署