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

Abstract

Resumo-O uso de antenas direcionais em redes sem fio tem sido considerado um mecanismo promissor para melhorar a utilização do espaço aéreo, a vazão e reduzir interferências. Porém, os protocolos MAC direcionais apresentam desafios e restrições que necessitam de soluções otimizadas. Este trabalho apresenta soluções para alguns destes problemas. Mais precisamente, este trabalho apresenta algumas alternativas para aumentar a vazão e a justiça dos protocolos MAC direcionais. Quando comparado com outros protocolos e mecanismos, a técnica proposta obteve ganhos de até 300% em vazão por fluxo e 86% em justiça.

Directional Pulse/Tone Based Channel Reservation with Deafness Avoidance

“…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.…”

“…However, this protocol does not provide a fair assignment of network resources. The DVCS-DA (Directional Virtual Carrier Sensing with Deafness Avoidance -2012) [25] resorts to receiver initiated communications with the RTR frame combined to a traffic flow oriented deafness prediction mechanism. Unlike RI-DMAC, the DVCS-DA is able to provide fair use of the network resources, even in cases where the next packet information fails.…”

“…Furthermore, DPTCR-DA uses a deafness prediction mechanism to decide whether a node will try to begin a receiver initiated communication using a tone signal. The referred mechanism is based on local traffic flow information, in a similar way to the used by DVCS-DA [25]. Pulse/tone signal based channel reservation, and the deafness prediction mechanism will be presented next.…”

“…For each flow i, α can be based on the information contained in the active flow table. Other possible ways to perform this estimation are described by [25].…”

“…Thus, the DPTCR-DA is able to attain a lower latency as compared to RI-DMAC and DVCS. As described by [25], after a successful transmission of a data frame, the sender node will perform the deafness estimation. In case of indication of deafness occurrence, the sender node enters in deafness mitigation mode.…”