Deafness Resilient MAC Protocol for Directional Communications

Abstract

SUMMARYIt is known that wireless ad hoc networks employing omnidirectional communications suffer from poor network throughput due to inefficient spatial reuse. Although the use of directional communications is expected to provide significant improvements in this regard, the lack of efficient mechanisms to deal with deafness and hidden terminal problems makes it difficult to fully explore its benefits. The main contribution of this work is to propose a Medium Access Control (MAC) scheme which aims to lessen the effects of deafness and hidden terminal problems in directional communications without precluding spatial reuse. The simulation results have shown that the proposed directional MAC provides significant throughput improvement over both the IEEE802.11DCF MAC protocol and other prominent directional MAC protocols in both linear and grid topologies.

Directional Pulse/Tone Based Channel Reservation with Deafness Avoidance

“…A switched beam antenna consists of dividing the antenna in n sectors, where each one covers an angle equal to 360/n • . Switched beam antennas are expected to be produced at a much lower cost, while being able to provide most of the benefits of a more sophisticated system [11]. Hence, switched beam antennas seems to be a feasible option as a first generation technology to be used in ad hoc networks.…”

“…Indeed, some of existing directional MAC protocols developed mechanisms which aim to perform this task. In what follows [19] No Directional No DMAC [9] No Directional No ToneDMAC [14] Yes Directional Tone RI-DMAC [24] No Directional RTR CW-DMAC [13] No Omnidirectional No DC-DMAC [11] Yes Omnidirectional No DVCS-DA [25] No Directional RTR DPTCR-DA No Directional Pulse/Tone we review some directional MAC protocols and techniques which are closely related to this work.…”

“…This protocol does not address fairness, but it reduces the unnecessary backoff window increase due to deafness. The DC-DMAC (Dual Channel Directional MAC -2010) [11] also proposed the use of RTS/CTS in omnidirectional mode (in a control channel). This protocol relies on a geometric concept based on the antenna range to identify deafness occurrence in many cases.…”

“…As described by references [9] [10] [11] [12], the development of an efficient directional MAC protocol is not trivial due to directional hidden and directional exposed terminal problems. On top of that, directional communications also suffer from "deafness" problem [11]. As the directional antennas are typically halfduplex, when a node points its antenna direction towards a particular sector/direction, the signals arriving from other sectors/directions are not captured.…”

Proposta de Tratamento do Problema de Surdez de Antenas em Comunicações Direcionais

“…Paralelamente, identificou-se o problema de surdez em comunicações direcionais quando da proposta do protocolo Directional MAC Protocol (DMAC) [3]. O problema de surdez pode levar a uma distribuição irregular nos recursos do meio em cenários onde os nós se comunicam direcionalmente, levando a uma distribuição injusta dos recursos do espectro, [1] O presente trabalho propõe uma técnica de tratamento do problema de surdez em comunicações direcionais, que se baseia em informações dos fluxos de tráfego para evitar a ocorrência de situações de surdez. A validação da técnica proposta se deu via simulação através do uso do simulador de redes Qualnet [10].…”