Conference Paper

On Spatial Reuse and Capture in Ad Hoc Networks

Univ. of South Carolina, Columbia
DOI: 10.1109/WCNC.2008.291 Conference: Wireless Communications and Networking Conference, 2008. WCNC 2008. IEEE
Source: IEEE Xplore


Neighbors of both the transmitter and the receiver must keep quiet in a 802.11 wireless network as it requires bidirectional exchange, i.e., nodes reverse their roles as transmitters and receivers, for transmitting a single DATA frame. To reduce role reversals and to improve spatial reuse, a piggybacked acknowledgment based approach has been proposed to enable concurrent transmissions. Recent findings on physical layer capture show that it is possible to capture a frame of interest in the presence of concurrent interference and that the SINR threshold is dependent on the relative order in which the frame and the interference arrive at the receiver. In this paper, we show that it is possible to exploit capture and increase concurrent transmissions in wireless adhoc networks. We develop a distributed channel access scheme and demonstrate that it offers significant throughput gain particularly at lower data rates.

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    • "To achieve spatial reuse maximization, MAC protocol must coordinate the hosts to access the common medium depending on their distances to avoid interfering another ongoing transmission whilst not to prevent an upcoming nondestructive transmission but declared as possibly interferer because of the traditional PCS and VCS mechanisms [21]. 4-phase MAC protocol of 802.11 alleviates highly the hidden terminal problem, whilst posing another challenge called exposed terminal problem which is a critical issue to be considered in order to improve spatial reuse [22]. As depicted inFig. "

    Full-text · Article · Feb 2016 · International Journal of Advanced Computer Science and Applications
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    • "Thus, in packet radio, capture alone is not sufficient for successful reception, rather the receiver must be synchronized and locked onto the captured signal as well. Several research contributions analyze possible collision constellations and their effect on packet reception [14], [23], and propose a new receiver design that releases the lock when a stronger packet arrives, discards the first and receives the second packet, the so-called message-in-message (MIM) capture [14], [28]. Subsequent work applies these insights to improve network throughput. "
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    ABSTRACT: Numerous studies have shown that concurrent transmissions can help to boost wireless network performance despite the possibility of packet collisions. However, while these works provide empirical evidence that concurrent transmissions may be received reliably, existing signal capture models only partially explain the root causes of this phenomenon. We present a comprehensive mathematical model for MSK-modulated signals that makes the reasons explicit and thus provides fundamental insights on the key parameters governing the successful reception of colliding transmissions. A major contribution is the closed-form derivation of the receiver bit decision variable for an arbitrary number of colliding signals and constellations of power ratios, time offsets, and carrier phase offsets. We systematically explore the factors for successful packet delivery under concurrent transmissions across the whole parameter space of the model. We confirm the capture threshold behavior observed in previous studies but also reveal new insights relevant to the design of optimal protocols: We identify capture zones depending not only on the signal power ratio but also on time and phase offsets.
    Full-text · Article · Aug 2014 · IEEE Transactions on Wireless Communications
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    ABSTRACT: Recent experimental studies on physical layer capture in 802.11 based networks have demonstrated that the minimum signal-to-interference ratio required for successful reception of a frame depends upon the order of arrivals of the sender's frame and the interference, and it is much less when the sender's frame arrives earlier. This differential capture capability (DCC) leads to a very small interference range around the receiver once it starts receiving a frame, and hence it allows considerable reduction in the required carrier sensing range. While the DCC feature of receivers helps alleviate some hidden and exposed terminal problems, there still remains many exposed nodes. In this paper, we further exploit the DCC feature to mitigate the problem of these exposed terminals that remain even after optimum reduction in carrier sensing range. We propose a liberal carrier sensing scheme that helps identify some of the exposed prospective receivers by using some already available local information and allow them to initiate secondary sessions. Through extensive simulations we demonstrate that the proposed scheme offers significant throughput gain over the conventional carrier sensing scheme that ignores the DCC feature.
    No preview · Article · Jan 2010
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