Receiver-Initiated Handshaking MAC Based on Traffic Estimation for Underwater Sensor Networks

In underwater sensor networks (UWSNs), the unique characteristics of acoustic channels have posed great challenges for the design of medium access control (MAC) protocols. The long propagation delay problem has been widely explored in recent literature. However,the long preamble problem with acoustic modems revealed in real experiments brings new challenges to underwater MAC design. The overhead of control messages in handshaking-based protocols becomes significant due to the long preamble in underwater acoustic modems. To address this problem, we advocate the receiver-initiated handshaking method with parallel reservation to improve the handshaking efficiency. Despite some existing works along this direction, the data polling problem is still an open issue. Without knowing the status of senders, the receiver faces two challenges for efficient data polling: when to poll data from the sender and how much data to request. In this paper, we propose a traffic estimation-basedreceiver-initiated MAC(TERI-MAC)to solve this problem with an adaptive approach. Data polling in TERI-MAC depends on an online approximation of traffic distribution. It estimates the energy efficiency and network latency and starts the data request only when the preferred performance can be achieved. TERI-MAC can achieve a stable energy efficiency with arbitrary network traffic patterns. For traffic estimation, we employ a resampling technique to keep a small computation and memory overhead. The performance of TERI-MAC in terms of energy efficiency, channel utilization, and communication latency is verified in simulations. Our results show that, compared with existing receiver-initiated-based underwater MAC protocols, TERI-MAC can achieve higher energy efficiency at the price of a delay penalty. This confirms the strength of TERI-MAC for delay-tolerant applications

Receiver-Initiated Handshaking MAC Based On Traffic Estimation for Underwater Sensor Networks

In underwater sensor networks (UWSNs), the unique characteristics of acoustic channels have posed great challenges for the design of medium access control (MAC) protocols. The long propagation delay problem has been widely explored in recent literature. However, the long preamble problem with acoustic modems revealed in real experiments brings new challenges to underwater MAC design. The overhead of control messages in handshaking-based protocols becomes significant due to the long preamble in underwater acoustic modems. To address this problem, we advocate the receiver-initiated handshaking method with parallel reservation to improve the handshaking efficiency. Despite some existing works along this direction, the data polling problem is still an open issue. Without knowing the status of senders, the receiver faces two challenges for efficient data polling: when to poll data from the sender and how much data to request. In this paper, we propose a traffic estimation-based receiver-initiated MAC (TERI-MAC) to solve this problem with an adaptive approach. Data polling in TERI-MAC depends on an online approximation of traffic distribution. It estimates the energy efficiency and network latency and starts the data request only when the preferred performance can be achieved. TERI-MAC can achieve a stable energy efficiency with arbitrary network traffic patterns. For traffic estimation, we employ a resampling technique to keep a small computation and memory overhead. The performance of TERI-MAC in terms of energy efficiency, channel utilization, and communication latency is verified in simulations. Our results show that, compared with existing receiver-initiated-based underwater MAC protocols, TERI-MAC can achieve higher energy efficiency at the price of a delay penalty. This confirms the strength of TERI-MAC for delay-tolerant applications

A Cross-Layer Duty Cycle MAC Protocol Supporting a Pipeline Feature for Wireless Sensor Networks

Although the conventional duty cycle MAC protocols for Wireless Sensor Networks (WSNs) such as RMAC perform well in terms of saving energy and reducing end-to-end delivery latency, they were designed independently and require an extra routing protocol in the network layer to provide path information for the MAC layer. In this paper, we propose a new cross-layer duty cycle MAC protocol with data forwarding supporting a pipeline feature (P-MAC) for WSNs. P-MAC first divides the whole network into many grades around the sink. Each node identifies its grade according to its logical hop distance to the sink and simultaneously establishes a sleep/wakeup schedule using the grade information. Those nodes in the same grade keep the same schedule, which is staggered with the schedule of the nodes in the adjacent grade. Then a variation of the RTS/CTS handshake mechanism is used to forward data continuously in a pipeline fashion from the higher grade to the lower grade nodes and finally to the sink. No extra routing overhead is needed, thus increasing the network scalability while maintaining the superiority of duty-cycling. The simulation results in OPNET show that P-MAC has better performance than S-MAC and RMAC in terms of packet delivery latency and energy efficiency

Cooperative Collision Avoidance at Intersections: Algorithms and Experiments

In this paper, we leverage vehicle-to-vehicle (V2V) communication technology to implement computationally efficient decentralized algorithms for two-vehicle cooperative collision avoidance at intersections. Our algorithms employ formal control theoretic methods to guarantee a collision-free (safe) system, whereas overrides are only applied when necessary to prevent a crash. Model uncertainty and communication delays are explicitly accounted for by the model and by the state estimation algorithm. The main contribution of this work is to provide an experimental validation of our method on two instrumented vehicles engaged in an intersection collision avoidance scenario in a test track

Avaliação de disciplinas de consulta em protocolo de controle de acesso ao meio iniciado pelo receptor para redes sem fio AD HOC

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, 2014.O estudo de disciplinas de consulta para protocolos da sub-camada de controle de acesso ao meio (MAC, do inglês, Medium Access Control ) iniciados pelo receptor para redes ad hoc não tem recebido muita atenção na literatura, e esquemas simples como a consulta cíclica e a priorização uniforme são normalmente assumidos. Porém, não apenas a ordem, mas também a taxa com a qual os nós são consultados é importante: uma taxa de consulta que é muito baixa pode levar a uma baixa vazão e longos atrasos, enquanto que o oposto pode acarretar um tráfego de controle excessivo e um número maior de colisões de quadros. Idealmente, um protocolo MAC iniciado pelo receptor teria seu melhor desempenho se os nós pudessem saber “quem” e “quando” consultar baseados na disponibilidade de dados em seus vizinhos. A primeira parte desta dissertação investiga um protocolo MAC para comunicação ponto-a-ponto (“unicast”) que segue o paradigma de transmissão com iniciativa do receptor, baseado na reversão do algoritmo de recuo exponencial binário (BEB, do inglês, binary exponential backoff ) do padrão IEEE 802.11, como forma de controlar a taxa com que os nós são consultados. Com o algoritmo BEB, a taxa de consulta é auto-regulada de acordo com as condições de canal e de tráfego. Além disso, o reordenamento de quadro nas filas - onde um quadro pode ser transmitido ao ser consultado sem a necessidade de estar na cabeça da fila - e um novo quadro de controle, o NTS (do inglês, Nothing-to-send), cujo papel é avisar ao nó consultor que não há quadros de dados disponíveis, são apresentados para agilizar os turnos de consulta. O desempenho do protocolo MAC iniciado pelo receptor baseado no algoritmo BEB é investigado sob três disciplinas de consulta: uma consulta cíclica sem prioridades (“Round-robin”), uma que visa a justiça de vazão entre os nós, a disciplina de justiça proporcional (PF, do inglês, proportional fair ) e uma que prioriza os nós de acordo com a probabilidade de sucesso de estabelecimento de conexão (LSH, do inglês, likelihood of successful handshake). Comparações com o padrão IEEE 802.11 em relação à sobrecarga de controle, atraso, justiça, e vazão, de acordo com diferentes topologias e cenários de tráfego, são apresentadas. A partir dos resultados obtidos na avaliação das três disciplinas, é proposta uma variação da estratégia de consulta que seleciona dinamicamente o algoritmo a ser utilizado na escolha do destino da consulta. O protocolo MAC iniciado pelo receptor com o algoritmo BEB revertido combinado a esta nova estratégia de consulta denominou-se de Receiver-Initiated MAC with Adaptive Polling Discipline (RIMAP), um protocolo MAC para comunicação ponto-a-ponto (“unicast”) que dinamicamente seleciona uma disciplina de consulta de acordo com a contenção do canal e a homogeneidade da qualidade do enlace de todos os vizinhos. Para isso, duas disciplinas de consulta são consideradas: o LSH e PF. O comportamento adaptativo é controlado por dois parâmetros de comutação que podem ser ajustados para se obter um compromisso entre o desempenho de justiça e de vazão/atraso. O desempenho do RIMAP é avaliado com simulações a eventos discretos sob topologias com terminais escondidos, transmissões concorrentes, e tráfego saturado. Adicionalmente, seu desempenho é comparado com o mesmo protocolo baseado no algoritmo BEB com as disciplinas de consulta fixadas (LSH e PF somente), assim como comparado com o MAC do padrão IEEE 802.11, o representante do paradigma iniciado pelo transmissor.The study of polling disciplines for receiver-initiated MAC protocols for ad hoc networks has not received much attention in the literature, and simple schemes such as round-robin or uniform prioritization are usually assumed. However, not only the order, but also the rate at which nodes are polled is significant: a polling rate that is too slow may render low throughput and high delays, whereas the opposite may lead to excessive control trafic and frame collisions. Ideally, a receiverinitiated MAC would perform best if nodes could know “whom” and “when” to poll based on data availability. The first part of this work investigates a receiver-initiated unicast MAC protocol that is based on reversing the binary exponential backoff (BEB) algorithm of the IEEE 802.11 as a means to control the rate at which nodes are polled. With the BEB algorithm, the polling rate is self-regulated according to channel and traffic conditions. Additionally, frame reordering at queues _ where a frame can be transmitted when polled with no need to be in the head of queue _ and a new control frame, the Nothing-to-send (NTS), whose role is to notify the polling node that there is no data frame available, are introduced to speed up polling rounds. The performance of the BEBbased receiver-initiated MAC is investigated under three polling disciplines: a cyclic polling without priorities (“Round-robin”), one that targets throughput fairness among nodes, the proportional fair (PF) discipline, and one that prioritizes nodes according to the likelihood of successful handshake (LSH). Comparisons with the IEEE 802.11 with respect to control overhead, delay, fairness, and throughput, according to different topologies and traffic scenarios, are presented. From the results obtained in the evaluation of the three disciplines, it is proposed a variation of the polling strategy that selects dynamically the algorithm to be utilized in the choice of the polling destination. The receiver-initiated MAC protocol with the BEB algorithm combined with this new strategy is named Receiver-Initiated MAC with Adaptive Polling Discipline (RIMAP), a unicast MAC protocol that dynamically selects a polling discipline according to channel contention and link quality homogeneity to all neighbors. For that, two polling disciplines are considered: the LSH and the Proportional Fair (PF). The adaptive behavior is controlled by two switching parameters that can be tuned to trade off fairness with throughput-delay performance. RIMAP performance is evaluated with discrete-event simulations under topologies with hidden terminals, concurrent transmissions, and saturated traffic. Also, its performance is compared with the same BEB-based MAC protocol under fixed polling disciplines (LSH or PF only), as well as with the IEEE 802.11 DCF MAC, a representative of sender-initiated paradigms

Position-based routing and MAC protocols for wireless ad-hoc networks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.This thesis presents the Forecasting Routing Technique (FORTEL), a routing protocol for Mobile Ad-Hoc Networks (MANETs) based on the nodes’ Location Information. FORTEL stores the nodes’ location information in the Location Table (LT) in order to construct routes between the source and the destination nodes. FORTEL follows the source routing strategy, which has rarely been applied in position-based routing. According to the source routing strategy, the end-to-end route is attached to the packet, therefore, the processing cost, in regards to the intermediate nodes that simply relay the packet according to route, is minimized. FORTEL’s key mechanisms include: first, the location update scheme, employed to keep the LT entries up-to-date with the network topology. Besides the mobility variation and the constant rate location update schemes applied, a window location update scheme is presented to increase the LT’s information accuracy. Second, the switching mechanism, between “Hello” message and location update employed, to reduce the protocol’s routing overhead. Third and most important is the route computation mechanism, which is integrated with a topology forecasting technique to construct up-to-date routes between the communication peers, aiming to achieve high delivery rate and increase the protocol robustness against the nodes’ movement. FORTEL demonstrates higher performance as compared to other MANET’s routing protocols, and it delivers up to 20% more packets than AODV and up to 60 % more than DSR and OLSR, while maintaining low levels of routing overhead and network delay at the same time. The effectiveness of the window update scheme is also discussed, and it proves to increase FORTEL’s delivery rate by up to 30% as compared to the other update schemes. A common and frequently occurring phenomenon, in wireless networks, is the Hidden Terminal problem that significantly impacts the communication performance and the efficiency of the routing and MAC protocols. Beaconless routing approach in MANETs, which delivers data packets without prior knowledge of any sort `of information, suffers from packet duplication caused by the hidden nodes during the contention process. Moreover, the throughput of the IEEE MAC protocol decreases dramatically when the hidden terminal problem occurs. RTS/CTS mechanism fails to eliminate the problem and can further degrade the network’s performance by introducing additional overhead. To tackle these challenges, this thesis presents two techniques, the Sender Suppression Algorithm and the Location-Aided MAC, where both rely on the nodes’ position to eliminate packet duplication in the beaconless routing and improve the performance of the 802.11 MAC respectively. Both schemes are based on the concept of grouping the nodes into zones and assign different time delay to each one. According to the Sender Suppression Algorithm, the sender’s forwarding area is divided into three zones, therefore, the local timer, set to define the time that the receiver has to wait before responding to the sender’s transmission, is added to the assigned zone delay. Following the first response, the sender interferes and suppresses the receivers with active timer of. On the other hand, the Location-Aided MAC, essentially a hybrid MAC, combines the concepts of time division and carrier sensing. The radio range of the wireless receiver is partitioned into four zones with different zone delays assigned to each zone. Channel access within the zone is purely controlled by CSMA/CA protocol, while it is time-based amongst zones. The effectiveness of the proposed techniques is demonstrated through simulation tests. Location-Aided MAC considerably improves the network’s throughput compared to CSMA/CA and RTS/CTS. However, remarkable results come when the proposed technique and the RTS/CTS are combined, which achieves up to 20% more throughput as compared to the standalone RTS/CTS. Finally, the thesis presents a novel link lifetime estimation method for greedy forwarding to compute the link duration between two nodes. Based on a newly introduced Stability-Aware Greedy (SAG) scheme, the proposed method incorporates the destination node in the computation process and thus has a significant advantage over the conventional method, which only considers the information of the nodes composing the link

Forward focus: using routing information to improve medium access control in ad hoc networks

Summary Multihop packet forwarding is a vital process in an ad hoc network. All ad hoc networking protocols, but particularly routing and medium access control protocols, must work together in order for the network to be successful. However, current MAC protocols such as IEEE 802.11 do not consider this multihop nature at all. This work develops a modification to 802.11 that focuses on forwarding packets. Routing information is utilized to streamline the sharing of the medium, by allowing forwarding nodes to reuse an already-acquired channel. Using forward focus (FF), nodes are encouraged to participate in the forwarding process and are rewarded for doing so. Simulation-generated performance evaluations reveal that the result is a MAC protocol with improved efficiency and effectiveness

Position-based routing and MAC protocols for wireless ad-hoc networks

This thesis presents the Forecasting Routing Technique (FORTEL), a routing protocol for Mobile Ad-Hoc Networks (MANETs) based on the nodes' Location Information. FORTEL stores the nodes' location information in the Location Table (LT) in order to construct routes between the source and the destination nodes. FORTEL follows the source routing strategy, which has rarely been applied in position-based routing. According to the source routing strategy, the end-to-end route is attached to the packet, therefore, the processing cost, in regards to the intermediate nodes that simply relay the packet according to route, is minimized. FORTEL's key mechanisms include: first, the location update scheme, employed to keep the LT entries up-to-date with the network topology. Besides the mobility variation and the constant rate location update schemes applied, a window location update scheme is presented to increase the LT's information accuracy. Second, the switching mechanism, between "Hello" message and location update employed, to reduce the protocol's routing overhead. Third and most important is the route computation mechanism, which is integrated with a topology forecasting technique to construct up-to-date routes between the communication peers, aiming to achieve high delivery rate and increase the protocol robustness against the nodes' movement. FORTEL demonstrates higher performance as compared to other MANET's routing protocols, and it delivers up to 20% more packets than AODV and up to 60 % more than DSR and OLSR, while maintaining low levels of routing overhead and network delay at the same time. The effectiveness of the window update scheme is also discussed, and it proves to increase FORTEL's delivery rate by up to 30% as compared to the other update schemes. A common and frequently occurring phenomenon, in wireless networks, is the Hidden Terminal problem that significantly impacts the communication performance and the efficiency of the routing and MAC protocols. Beaconless routing approach in MANETs, which delivers data packets without prior knowledge of any sort `of information, suffers from packet duplication caused by the hidden nodes during the contention process. Moreover, the throughput of the IEEE MAC protocol decreases dramatically when the hidden terminal problem occurs. RTS/CTS mechanism fails to eliminate the problem and can further degrade the network's performance by introducing additional overhead. To tackle these challenges, this thesis presents two techniques, the Sender Suppression Algorithm and the Location-Aided MAC, where both rely on the nodes' position to eliminate packet duplication in the beaconless routing and improve the performance of the 802.11 MAC respectively. Both schemes are based on the concept of grouping the nodes into zones and assign different time delay to each one. According to the Sender Suppression Algorithm, the sender's forwarding area is divided into three zones, therefore, the local timer, set to define the time that the receiver has to wait before responding to the sender's transmission, is added to the assigned zone delay. Following the first response, the sender interferes and suppresses the receivers with active timer of. On the other hand, the Location-Aided MAC, essentially a hybrid MAC, combines the concepts of time division and carrier sensing. The radio range of the wireless receiver is partitioned into four zones with different zone delays assigned to each zone. Channel access within the zone is purely controlled by CSMA/CA protocol, while it is time-based amongst zones. The effectiveness of the proposed techniques is demonstrated through simulation tests. Location-Aided MAC considerably improves the network's throughput compared to CSMA/CA and RTS/CTS. However, remarkable results come when the proposed technique and the RTS/CTS are combined, which achieves up to 20% more throughput as compared to the standalone RTS/CTS. Finally, the thesis presents a novel link lifetime estimation method for greedy forwarding to compute the link duration between two nodes. Based on a newly introduced Stability-Aware Greedy (SAG) scheme, the proposed method incorporates the destination node in the computation process and thus has a significant advantage over the conventional method, which only considers the information of the nodes composing the link.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Position-based routing and MAC protocols for wireless ad-hoc networks

This thesis presents the Forecasting Routing Technique (FORTEL), a routing protocol for Mobile Ad-Hoc Networks (MANETs) based on the nodes' Location Information. FORTEL stores the nodes' location information in the Location Table (LT) in order to construct routes between the source and the destination nodes. FORTEL follows the source routing strategy, which has rarely been applied in position-based routing. According to the source routing strategy, the end-to-end route is attached to the packet, therefore, the processing cost, in regards to the intermediate nodes that simply relay the packet according to route, is minimized. FORTEL's key mechanisms include: first, the location update scheme, employed to keep the LT entries up-to-date with the network topology. Besides the mobility variation and the constant rate location update schemes applied, a window location update scheme is presented to increase the LT's information accuracy. Second, the switching mechanism, between "Hello" message and location update employed, to reduce the protocol's routing overhead. Third and most important is the route computation mechanism, which is integrated with a topology forecasting technique to construct up-to-date routes between the communication peers, aiming to achieve high delivery rate and increase the protocol robustness against the nodes' movement. FORTEL demonstrates higher performance as compared to other MANET's routing protocols, and it delivers up to 20% more packets than AODV and up to 60 % more than DSR and OLSR, while maintaining low levels of routing overhead and network delay at the same time. The effectiveness of the window update scheme is also discussed, and it proves to increase FORTEL's delivery rate by up to 30% as compared to the other update schemes. A common and frequently occurring phenomenon, in wireless networks, is the Hidden Terminal problem that significantly impacts the communication performance and the efficiency of the routing and MAC protocols. Beaconless routing approach in MANETs, which delivers data packets without prior knowledge of any sort `of information, suffers from packet duplication caused by the hidden nodes during the contention process. Moreover, the throughput of the IEEE MAC protocol decreases dramatically when the hidden terminal problem occurs. RTS/CTS mechanism fails to eliminate the problem and can further degrade the network's performance by introducing additional overhead. To tackle these challenges, this thesis presents two techniques, the Sender Suppression Algorithm and the Location-Aided MAC, where both rely on the nodes' position to eliminate packet duplication in the beaconless routing and improve the performance of the 802.11 MAC respectively. Both schemes are based on the concept of grouping the nodes into zones and assign different time delay to each one. According to the Sender Suppression Algorithm, the sender's forwarding area is divided into three zones, therefore, the local timer, set to define the time that the receiver has to wait before responding to the sender's transmission, is added to the assigned zone delay. Following the first response, the sender interferes and suppresses the receivers with active timer of. On the other hand, the Location-Aided MAC, essentially a hybrid MAC, combines the concepts of time division and carrier sensing. The radio range of the wireless receiver is partitioned into four zones with different zone delays assigned to each zone. Channel access within the zone is purely controlled by CSMA/CA protocol, while it is time-based amongst zones. The effectiveness of the proposed techniques is demonstrated through simulation tests. Location-Aided MAC considerably improves the network's throughput compared to CSMA/CA and RTS/CTS. However, remarkable results come when the proposed technique and the RTS/CTS are combined, which achieves up to 20% more throughput as compared to the standalone RTS/CTS. Finally, the thesis presents a novel link lifetime estimation method for greedy forwarding to compute the link duration between two nodes. Based on a newly introduced Stability-Aware Greedy (SAG) scheme, the proposed method incorporates the destination node in the computation process and thus has a significant advantage over the conventional method, which only considers the information of the nodes composing the link.EThOS - Electronic Theses Online ServiceGBUnited Kingdo