CSMA/CA in Time and Frequency Domains
CSMA/CA in Time and Frequency Domains
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DOI：
10.1109/icnp.2015.16
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发表时间：
2015-11
期刊：
影响因子：
--
通讯作者：
J. Herzen;A. Banchs;V. Shneer;Patrick Thiran
中科院分区：
文献类型：
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作者：
J. Herzen;A. Banchs;V. Shneer;Patrick Thiran
最近已经表明，“灵活信道化”，即无线站在每帧的基础上调整它们的频带，在实践中是可行的。在本文中，我们提出了TF-CSMA/CA，一种灵活的信道化，在时域和频域调度数据包的算法。TF-CSMA/CA是IEEE 802.11使用的CSMA/CA协议的简单扩展。与现有的信道化方案相反，它是完全分布式的，并且它仅对分组冲突、成功传输和载波侦听做出反应。使用TF-CSMA/CA，当站点涉及冲突时，它在时域和频域两者中执行退避。也在频域中的回退允许发射机在时域中更加高效和积极，这显著降低了最近的802.11 PHY层存在的严重开销。然而，主要的挑战是，台站需要某种程度的自组织，以便找到可变宽度的频谱带，最大限度地减少干扰，同时仍然有效地使用可用频谱。使用分析和模拟，我们表明，这样的扩展的CSMA/CA的频域大大提高了吞吐量和公平性。值得注意的是，它使基站能够在不使用通信的情况下找到适当大小的无干扰频谱带-仅依赖于作为隐式信号的冲突和成功。
It has recently been shown that "flexible channelization", whereby wireless stations adapt their spectrum bands on a per-frame basis, is feasible in practice. In this paper, we propose TF-CSMA/CA, an algorithm for flexible channelization that schedules packets in time and frequency domains. TF-CSMA/CA is a simple extension of the CSMA/CA protocol used by IEEE 802.11. Contrary to existing channelization schemes, it is entirely distributed and it reacts only to packet collisions, successful transmissions and carrier sensing. With TF-CSMA/CA, when a station is involved in a collision, it performs backoff in both time and frequency domains. Backing off also in the frequency domain allows the transmitters to be much more efficient and aggressive in the time domain, which significantly reduces the severe overheads present with recent 802.11 PHY layers. The main challenge, however, is that the stations need some level of self-organization in order to find spectrum bands of variable widths that minimize interference, while still efficiently using the available spectrum. Using analysis and simulations, we show that such an extension of CSMA/CA to the frequency domain drastically improves both throughput and fairness. Notably, it enables the stations to find interference-free spectrum bands of appropriate size using no communication -- relying only on collisions and successes as implicit signals.