Controlo de acesso ao meio fiável para redes ad hoc
সংরক্ষণ করুন:
| প্রকাশিত: | PQDT - Global (2012) |
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| প্রধান লেখক: | |
| প্রকাশিত: |
ProQuest Dissertations & Theses
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| বিষয়গুলি: | |
| অনলাইন ব্যবহার করুন: | Citation/Abstract Full Text - PDF |
| ট্যাগগুলো: |
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|---|---|---|---|
| 001 | 2956506698 | ||
| 003 | UK-CbPIL | ||
| 020 | |a 9798381670349 | ||
| 035 | |a 2956506698 | ||
| 045 | 2 | |b d20120101 |b d20121231 | |
| 084 | |a 189128 |2 nlm | ||
| 100 | 1 | |a de Jesus Semedo Gonçalves, Adilson | |
| 245 | 1 | |a Controlo de acesso ao meio fiável para redes ad hoc | |
| 260 | |b ProQuest Dissertations & Theses |c 2012 | ||
| 513 | |a Dissertation/Thesis | ||
| 520 | 3 | |a O protocolo de controlo de acesso ao meio (MAC) com maior popularidade em redes locais sem fios e em redes ad hoc e o IEEE 802.11. Este protocolo foi desenhado essencialmente para transmissoes do tipo unicast, apresentando elevada fiabilidade. Para transmissoes do tipo broadcast, o protocolo nao e fiavel devido a elevada probabilidade de colisao provocada pelo uso da janela de contencao de valor fixo, e ainda pela falta de um mecanismo de Acknowledgement (ACK) das tramas broadcast. Infelizmente, muito dos protocolos de encaminhamento geram elevadas quantidades do trafego broadcastpara troca de informacoes entre os nos, de forma a poderem descobrir e estabelecer rotas entre o no de origem e o no de destino. Este facto motiva o desenvolvimento de protocolos de controlo de acesso ao meio que apresentem elevada fiabilidade em cenarios multi-hop e, simultaneamente, exibem elevado desempenho em termos do debito.Esta dissertacao propoe um novo protocolo MAC para redes multi-hop. O protocolo proposto efectua a optimizacao da janela de contencao adoptada pelos nos com base na estatıstica da ocupacao do meio, com o objectivo de maximizar o debito do sistema numa rede multi-hop. Simultaneamente, o protocolo pretende obter valores de fiabilidade na transmissao das tramas que seja independentemente do tipo de trafego (unicast ou broadcast) a suportar. Os resultados obtidos com a proposta descrita nesta dissertacao exibem uma melhoria de desempenho, confirmando valores de fiabilidade constante para diferentes densidades de nos e quantidade de trafego unicast e broadcast. Nowadays the standard IEEE 802.11 is the most popular protocol for wireless local area networks and ad hoc networks. The medium access control scheme proposed in IEEE 802.11 was designed primarily for unicast transmissions, which exhibit high reliability. For broadcast transmissions the MAC scheme proposed in IEEE 802.11 is unreliable due to the absence of an acknowledgement scheme, which origins a high rate of collisions. Unfortunately, most of the routing protocols proposed for ad hoc networks generate large amounts of broadcast traffic, namely to exchange information related to the network topology, so that they can discover and establish new routes between source and destination nodes. This fact motivates the development of new medium access control schemes that should exhibit both high probability of successful transmission and high throughput in multi-hop scenarios for both types of broadcast and unicast traffic.This work proposes a new contention-based MAC protocol for multi-hop networks. The proposed protocol optimizes the individual contention window based on statistics collected from the channel. Simultaneously, the protocol seeks to obtain a constant probability of collision, independently of the types of traffic (broadcast/unicast). The results achieved with the proposed protocol shown an improvement in terms of throughput, and confirm that the probability of successful transmission is constant and does not depend on traffic’ s type nor on the number of nodes. | |
| 653 | |a Radio networks | ||
| 653 | |a Spread spectrum | ||
| 653 | |a Portable computers | ||
| 653 | |a Internet Protocol | ||
| 653 | |a Access control | ||
| 653 | |a Computer engineering | ||
| 653 | |a Electrical engineering | ||
| 773 | 0 | |t PQDT - Global |g (2012) | |
| 786 | 0 | |d ProQuest |t ProQuest Dissertations & Theses Global | |
| 856 | 4 | 1 | |3 Citation/Abstract |u https://www.proquest.com/docview/2956506698/abstract/embedded/6A8EOT78XXH2IG52?source=fedsrch |
| 856 | 4 | 0 | |3 Full Text - PDF |u https://www.proquest.com/docview/2956506698/fulltextPDF/embedded/6A8EOT78XXH2IG52?source=fedsrch |