CSMA/CN: Carrier Sense Multiple Access With Collision Notification
CSMA/CN: Carrier Sense Multiple Access With Collision Notification
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DOI：
10.1109/tnet.2011.2174461
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发表时间：
2012-04-01
影响因子：
3.7
通讯作者：
Nelakuditi, Srihari
中科院分区：
文献类型：
--
作者：
Sen, Souvik;Choudhury, Romit Roy;Nelakuditi, Srihari
无线发射机只有在完成整个传输后才会获悉数据包丢失并推断冲突。如果发射机能够及早检测到冲突[例如有线网络中具有冲突检测功能的载波侦听多路访问 (CSMA/CD)]，它可以立即中止其传输，从而释放信道以进行有用的通信。在无线网络中实现 CSMA/CD 有两个主要障碍。首先，无线发射机不能同时发射和侦听冲突。其次，发射机周围的任何信道活动可能都不是接收机冲突的指标。本文尝试使用一种称为 CSMA/CN（冲突通知）的新颖方案来近似无线网络中的 CSMA/CD。在 CSMA/CN 下，接收器使用 PHY 层信息来检测冲突并立即通知发送器。冲突通知由唯一的签名组成，与数据在同一通道上发送。发射机采用监听天线并执行签名相关来辨别该通知。一旦识别，发射器立即中止传输。我们表明，即使存在来自发射天线的强烈自干扰，也可以在收听者天线处可靠地检测到通知签名。 10 个 USRP/GNU 无线电的原型测试台证明了 CSMA/CN 的可行性和有效性。
A wireless transmitter learns of a packet loss and infers collision only after completing the entire transmission. If the transmitter could detect the collision early [such as with carrier sense multiple access with collision detection (CSMA/CD) in wired networks], it could immediately abort its transmission, freeing the channel for useful communication. There are two main hurdles to realize CSMA/CD in wireless networks. First, a wireless transmitter cannot simultaneously transmit and listen for a collision. Second, any channel activity around the transmitter may not be an indicator of collision at the receiver. This paper attempts to approximate CSMA/CD in wireless networks with a novel scheme called CSMA/CN (collision notification). Under CSMA/CN, the receiver uses PHY-layer information to detect a collision and immediately notifies the transmitter. The collision notification consists of a unique signature, sent on the same channel as the data. The transmitter employs a listener antenna and performs signature correlation to discern this notification. Once discerned, the transmitter immediately aborts the transmission. We show that the notification signature can be reliably detected at the listener antenna, even in the presence of a strong self-interference from the transmit antenna. A prototype testbed of 10 USRP/GNU Radios demonstrates the feasibility and effectiveness of CSMA/CN.