Access Priority Adaptation for Triggered Uplink Channel Access in 802.11ax WLANs
Access Priority Adaptation for Triggered Uplink Channel Access in 802.11ax WLANs
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DOI：
10.1109/icc45041.2023.10279066
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发表时间：
2023-05
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影响因子：
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通讯作者：
Vinicius Da Silva Goncalves;E. Knightly
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作者：
Vinicius Da Silva Goncalves;E. Knightly
上行链路多用户（MU）MIMO传输允许客户端同时向接入点（AP）发送独立的数据流，从而有效地倍增用于上行链路接入的无线信道的容量。由于分布式无线网络的固有限制，需要额外的协调来有效地实现上行链路MU-MIMO。触发上行链路接入（TUA）是唯一可以在Wi-Fi中发起上行链路MU-MIMO传输的机制：它使接入点（AP）能够开始同时的上行链路多用户（MU）传输。为了触发MU上行链路传输，AP必须首先使用增强型分布式信道接入（EDCA）来竞争信道，并赢得信道接入以在下行链路方向上广播触发帧。同时，具有缓冲用于上行链路传输的业务的客户端也使用相同的EDCA方法竞争信道接入。然而，上述机制在网络中引入了根本冲突。潜在地存在两个网络实体竞争用于相同分组的信道，即，AP竞争用于广播触发帧的信道，而具有缓冲用于上行链路传输的业务的客户端也竞争单用户（SU）信道接入。然而，虽然TUA MU传输优于SU上行链路，但不能完全禁用后者。在本文中，我们引入客户端接入操作（CAM）作为一种机制，使客户端能够动态地适应他们的信道接入优先级，以实现高效的上行链路MU-MIMO WLAN。通过在具有TUA机制的端到端测试平台中进行的实验，一个11 ax兼容网络，以及来自突发闭环应用程序的流量，我们表明CAM实现了吞吐量的增加和平均延迟高达65%的减少。此外，我们还表明，在相同的场景下，使用标准定义的访问自适应机制，总吞吐量会下降，平均延迟会急剧增加。
Uplink Multi-User (MU) MIMO transmissions allow clients to simultaneously transmit independent data streams to the Access Point (AP), effectively multiplying the capacity of the wireless channel for uplink access. Due to inherent limitations of the distributed wireless networks, extra coordination is required for effective implementation of uplink MU-MIMO. Triggered uplink access (TUA) is the only mechanism that can initiate an uplink MU-MIMO transmission in Wi-Fi: it enables an access point (AP) to start simultaneous uplink multi-user (MU) transmissions. To trigger a MU uplink transmission, the AP must first contend for the channel using the enhanced distributed channel access (EDCA) and win channel access to broadcast the trigger frame in the downlink direction. At the same time, clients that have traffic buffered for uplink transmission also contend for channel access using the same EDCA method. However, the aforementioned mechanism introduces a fundamental conflict in the network. There are potentially two network entities competing for the channel for the same packet, namely, the AP contends for the channel to broadcast the trigger frame, while the clients that have traffic buffered for uplink transmission also contend for single-user (SU) channel access. Yet, while TUA MU transmission is preferable to SU uplink, one cannot disable the latter entirely. In this paper, we introduce Client-side Access Manipulation (CAM) as a mechanism to enable clients to dynamically adapt their channel access priority in order to realize an efficient uplink MU-MIMO WLAN. Through experiments in an end-to-end testbed with the TUA mechanism, an 11ax compliant network, and traffic from bursty closed-loop applications we show that CAM achieves gains in throughput and up to 65% reduction in average latency. Moreover, we show that, on the same scenarios, the aggregate throughput decreases and the average latency increases sharply with the use of the standard's defined access adaptation mechanism.