Joint Transmission Rate, Power, and Carrier Sense Settings: An Initial Measurement Study

Abstract

Abstract-A substantial variety of control algorithms to adjust carrier sensing, transmission power, and transmission rate have been proposed for IEEE 802.11 wireless networks in the recent literature. Their objectives range from maximizing throughput, spatial reuse, and fairness to minimizing interference and congestion within the network. However, only a few of these have been implemented and analysed in practice, often because accessing and changing the necessary parameters in the wireless hardware is too difficult. Essentially, there is little understanding about the interactions of jointly adjusted transmission rate, power and carrier sense thresholds, and their impact on the aforementioned objectives. Therefore, in this paper, we focus on transmission rate, power and carrier sensing settings. We provide a detailed description of the common IEEE 802.11 radio hardware, especially in terms of carrier-sensing circuitry. We then present our results from our validation and initial measurement study, which demonstrate interactions between transmit power and rate under different carrier-sensing settings in a two link scenario. Our initial findings indicate there exists a limited number of ratepower combinations that achieve high performance in terms of either throughput and fairness both with and without carrier sensing. Furthermore, in the case of both strong and weak links exist in the network, turning carrier sensing off significantly improves performance.

hMAC: Enabling Hybrid TDMA/CSMA on IEEE 802.11 Hardware

“…Finally, a similar situation appears in networks that perform transmit power control on a per-link or per-packet basis, e.g. as suggested by [1], [5], [6], [7], [8], [12], [15], [18]. Fig.…”

Practical Power and Rate Control for WiFi

“…There is a significant amount of both theoretical and practical work on independently performing power [1]- [6], rate [7]- [12] and carrier sense control [13]- [17]. However, the interactions among these mechanisms cannot be overlooked, as they lead to tradeoffs [18]. In theory, one can improve spatial reuse, and consequently network capacity, by reducing the power or increasing the carrier sense threshold.…”

“…For instance, several theoretical and practical works focus on independently performing power [1]- [6], rate [7]- [12] and carrier sense control [13]- [17], which aim at adjusting the power, rate and carrier sense parameters, respectively, according to the measured link quality. As the interactions among these mechanisms lead to interesting tradeoffs [18], in this paper, we focus on their joint operation. Theoretical solutions in this context typically either require changes to the MAC (e.g., introducing a new frame type or adding additional information to Beacon frames) [19], [20], or assume cross-layer information from the MAC layer such as information about wireless neighbors and medium access state per link [20].…”