Interference aware (IA) MAC: an enhancement to IEEE802.11b DCF

Abstract

Abstract-The IEEE802.11 has been devised explicitly for low mobility and single access point scenarios, so its effectiveness is impaired in conditions with not negligible interference in ad hoc and/or in infrastructure modes. Well known problems typical of these scenarios are the so called hidden and exposed terminals. In this paper we propose and test a novel MAC layer for Wireless LANs, able to improve the performance of IEEE802.11 DCF (Distributed Coordination Function) in environments with high interference levels. The key point is to insert information about received power and interference levels into MAC control packets. By computing an estimation of the interference increasing due to an eventual transmission (forbidden with IEEE802.11 because blocked by the virtual carrier sensing), the number of parallel transmissions can grow significantly.

Performance Analysis of State-Free Geographic Forwarding Protocols for Wireless Sensor Networks

“…Interference by control messages employed by the MAC protocol for instance, at times of receiving CTS signals, nodes overhearing such signals would have to set their Network Allocation Vector (NAV) in accordance to the rules (802.11 timing semantics) on the basis of information received. This interferes with ongoing transmissions [8]. Mcouat, 2013 further explained that the separating distance between the interfering node and the receiving node helps drains the interfering nodes signal to a level that allows the receiving node to function normally within the low-bandwidth radio model as long as the interfering signal is less than the acceptable noise level.…”

Performance enhancement of overlapping BSSs via dynamic transmit power control

“…The problem of this scheme is that it requires metrics such as PER and interference level to be measured in real time which can increase the burden of system. Also Cesana et al [8] present an interference aware MAC for ad hoc mode network, in which each station transmits using RTS/CTS procedure, and the information about reception powers of RTS frames and interference levels is inserted into CTS packets. Utilizing the information, stations which overhear a CTS can tune their transmit powers such that they can transmit simultaneously without interfering with each other.…”

“…*Correspondence: wodeying21@kw.ac.kr Department of Electronics Convergence Engineering, Kwangwoon University, 447-1, Wolgye Dong, Nowon-GU, Seoul, Korea Many solutions have been suggested so far to dynamically control the transmit power of WLAN stations and thus to improve the overall throughput of the network [1,[4][5][6][7][8]. By adopting those schemes, stations are able to reduce their transmission ranges using only proper amount of transmit power, such that more stations can simultaneously transmit and thus the overall throughput is increased.…”

“…The previous works, however, may not be adopted in a practical WLAN system: For example, the problem of how to determine the proper power level is not fully investigated in [1,4]. Also [6] is based on assumptions that may not be possible in real world, [7] requires the real-time adaptation of a measurement algorithm, and power control scheme in [8] is limited to use only in ad hoc mode.…”

RTSS/CTSS: mitigation of exposed terminals in static 802.11-based mesh networks

“…Further, the resulting CS ranges are asymmetric in some cases, which can lead to unfairness. Another approach is to control the transmission power for better spatial reuse [3,10]. However, hidden and exposed terminals cannot both be eliminated by either adjusting the CS threshold or controlling the transmission power.…”