Wi-Fi 6

What is Wi-Fi 6 (802.11ax)?

Wi-Fi experiences a seismic change approximately every five years – and Wi-Fi 6 / Wi-Fi 6 (802.11ax) is the latest generation of Wi-Fi that bridges the performance gap towards ten gigabit speeds. 新的 Wi-Fi 标准将提供更快的网络性能，同时连接更多的设备，并将 Wi-Fi 从“尽最大努力”过渡到决定性的无线技术，后者已经成为互联网连接的事实媒介。 With an expected four-fold capacity increase over its 802.11ac Wave 2 predecessor, Wi-Fi 6 / Wi-Fi 6 (802.11ax) deployed in dense device environments will support higher service-level agreements (SLAs) to more concurrently connected users and devices with more diverse usage profiles.

详细信息

Wi-Fi 6 (802.11ax) offers a range of technical enhancements to optimize spectral efficiency, increase throughput and reduce power consumption. 其中包括：

OFDMA 和 MU-MIMO

正交频分多址 (OFDMA) 和多用户多入多出 (MU-MIMO) 是在未经许可的 Wi-Fi 频谱中提高可靠性和效率的技术。与前几代 Wi-Fi 不同，OFDMA 使 Wi-Fi 变得具有确定性，因为设备始终以最小的竞争获得更多关注。这有助于稳定 Wi-Fi 性能，尤其是在密度更高的环境中。

每个 Wi-Fi 被分成称为资源单元的较小子信道。接入点决定如何分配子信道，因为每个单独的 RU（或子信道）可以被寻址到同时服务的不同客户端。该技术通过创建更窄但专用的子信道来提高平均吞吐量（每个用户）。此外，OFDMA 提高了频谱效率并减少了延迟，同时支持异构用户（即 IM、电子邮件或轻量级 Web 浏览，而不是大量下载）。

重要的是要注意，OFDMA 和 MU-MIMO 提供互补技术来同时为多个用户服务。更具体地说，当多个连接传输有限数量的数据时，OFDMA 会得到最佳利用。OFDMA 在近、中和远所有范围内都有效，提供更低的延迟，并可用于减轻 OBSS 干扰问题。同时，MU-MIMO 可最好地为多个用户提供完全缓冲流量，在近到中距离时最有效。

上行链路 MU-MIMO

With Wi-Fi 6 (802.11ax), OFDMA and MU-MIMO are supported in downlink (from AP to stations) and uplink (from stations to AP). 应当注意，接入点在两个方向上调度传输。 This contrasts with pre-Wi-Fi 6 (802.11ax) networks (especially in uplink direction), where resource allocation is contention-based, with individual stations making the decision to appropriate the medium and transmit data.随着基站的增加，竞争也在增加。

子载波间隔和 MAC/PHY 增强功能

With Wi-Fi 6 (802.11ax), sub-carrier spacing is reduced, thereby enabling a 4X jump in the number of available data-tones and significantly increasing maximum PHY rates. 此外，附加的数据语音有助于支持多个用户结合 OFDMA。 Wi-Fi 6 (802.11ax) also optimizes spectral efficiency with more tones/channel, reduces overhead, bolsters outdoor operation and facilitates a quantum jump in highest achievable PHY rates. In addition, Wi-Fi 6 (802.11ax) APs maintains two separate network allocation vectors (NAVs) to prevent misbehavior and collisions. Last, but certainly not least, Wi-Fi 6 (802.11ax) features a 1024-QAM constellation (in contrast to 256-QAM for 11ac), enabling a 25% physical data rate increase that in combination with other Wi-Fi 6 (802.11ax) techniques offer up to 4x the capacity.