Towards Reliable Broadcast in ad hoc Networks

2006

The primary performance objective of a broadcast scheme in an ad-hoc wireless network is to reduce the total number of retransmissions needed to reach all nodes. Another (less appreciated) measure of interest is the broadcast latency, i.e., the amount of time required to complete the operation. We point out the tradeoff between the two measures and show how to significantly reduce the broadcast latency in networks whose MAC schemes are derivatives of IEEE 802.11.

13th International Conference on Advanced Communication Technology (ICACT2011), 2011

A new reliable cooperative MAC protocol called RCO-MAC is proposed, and the protocol's performance is evaluated with numerical analysis and computer simulation. The key concept for this RCO-MAC protocol is to give the responsibility of the error recovery by retransmission for a frame to the node that transmits the frame. The system throughput is used as a performance metric. According to numerical results, it is shown that the scheme proposed in this paper provides over 20% more system throughput than the rDCF scheme.

Proceedings of 2003 IEEE Wireless Communications and Networking Conference, 2003

Ad-hoc networking, though an attractive solution for many applications, still presents many unsolved issues, such as the hidden-terminal problem, flexible and prompt access, QoS provisioning, and efficient broadcast service. In this paper we present a MAC architecture able to solve the above issues in environments with no power consumption limitation, such as networks for inter-vehicle communications. This new architecture is based on a completely distributed access technique, RR-ALOHA, capable to dynamically establish on a slotted/framed structure a reliable single-hop broadcast channel for each active terminal on the network. Though the proposed MAC uses a slotted channel, it can be adapted to operate on the physical layer of different standards, including the UMTS Terrestrial Radio Access TDD, and the IEEE 802.11. The paper presents the mechanisms that compose the new MAC: the basic RR-ALOHA protocol, an efficient broadcast service and the reservation of point-to-point channels that exploit parallel transmissions. Some basic performance figures are discussed to prove the effectiveness of this protocol.

2008 Australasian Telecommunication Networks and Applications Conference, 2008

This paper investigates the relative performance of unicast and broadcast traffic traversing a one-hop ad hoc network utilising the 802.11 DCF. An extended Markov model has been developed and validated through computer simulation, which successfully predicts the respective performance of unicast and broadcast in a variety of mixed traffic scenarios. Under heavy network traffic conditions, a significant divergence is seen to develop between the performance of the two traffic classes-in particular, when network becomes saturated, unicast traffic is effectively given higher precedence over broadcast. As a result, the network becomes dominated by unicast frames, leading to poor rates of broadcast frame delivery.

2005

This paper presents the design, implementation and simulation results of a reliable Medium Access Control (MAC) broadcast protocol for Vehicular Ad hoc Networks for omni-directional and directional transmissions. The IEEE 802.11 MAC protocol uses control frames for handshaking to reliably communicate unicast data. In contrast, the broadcast data is transmitted without any control frames. This results in increased collisions due to hidden terminal problem, which in turn reduces the reliability of the broadcast service. This problem also exists in MAC protocols based on directional transmissions. To overcome this problem in Directional MAC (DMAC), we adapted Batch Mode Multicast MAC (BMMM) protocol, which uses control frames for broadcast transmissions. We implemented BMMM in NS-2 for omnidirectional and Directional MAC protocols. Simulations are run for city traffic scenarios and the results are compared with IEEE 802.11 unreliable broadcast support. The simulations and comparison are done for two variants of BMMM protocol implementation integrated with DMAC.

Wireless communications are becoming an important part of our everyday lifestyle. One major area that will have an enormous impact on the performance of wireless ad hoc networks is the medium access control (MAC) layer. Current random access MAC protocols for ad hoc networks support reliable unicast but not reliable broadcast. In this paper, we proposed a random access MAC protocol, Broadcast Support Multiple Access (BSMA), which improves broadcast reliability in ad hoc networks.

Journal of Interconnection Networks, 2003

In this paper, the IEEE 802.11 multiple access control protocol was modified for use in multi-channel, multi-hop ad hoc network, through the use of a new channel-status indicator. In particular, we have evaluated the improvement due to the multi-channel use. We report in this paper on the results of the throughput per node and the end-to-end delay for the modified IEEE 802.11 protocol for different network sizes. Using these results, we were able to propose a number of throughput scaling laws. Our simulation results show that the throughputs per node with multiple channels for the line and the grid ad hoc network topologies will increase by 47.89%, and by 139-163%, respectively, for networks with 16 to 64 nodes, as compared with that of single channel.

Computer Communications, 2005

The IEEE 802.11 standard supports several independent and equal-capacity communication channels, which can be shared simultaneously and accessed by mobile stations in existing wireless local area networks (WLANs). However, under the restriction of one transceiver per network adapter, these mobile stations can only access one of these communication channels and, thus, the remainder channels are wasted inevitably. A multichannel carrier sense multiple access (CSMA) protocol, multichannel multiple access (MMA) protocol, is proposed in the paper for supporting parallel transmissions under the above single transceiver constraint. The MMA protocol enables mobile stations to contend for access of multiple data-transferring channels through the use of a dedicated service channel during each contention reservation interval (CRI). After granting the access right of these channels, these mobile stations can transmit data frames over different channels by using a pre-defined channel scheduling algorithm (CSA) in a distributed manner. The time complexity of the proposed heuristic CSA is O(jXjlogjXjCjXj!M 2 ) where jXj and M denote the number of successful requests in the CRI and the number of available channels, respectively. An improved MMA C protocol with extending reserved transmission opportunities is also introduced and the goal is to maximize the channel utilization further. Simulation results show that the proposed MMA with CSA achieves a much higher throughput than conventional IEEE 802.11 WLAN with single channel. Simulation results also indicate that the achievable peek network throughput is not linearly proportional with the number of channels because of the native collision problem caused by single transceiver. q

2010 International Conference on Information Science and Applications, 2010

In this paper, a new reliable cooperative MAC protocol, which can enhance the system throughput under bad wireless channel environments, is proposed, and the protocol's performance is evaluated with a computer simulation. The system throughput and average delay, except queuing delay, are used as performance metrics. The numerical results show that the scheme proposed in this paper provides 24% more system throughput than the rDCF scheme. On the other hand, the proposed scheme has a higher system performance in the average delay when the number of terminals is small but provides slightly worse system performance when the number of terminals increases. That is because the system performance is mostly dominated by channel contention when the number of terminals becomes large and because retransmission timers after transmissions of CRTS and DATA frames are set with a greater value than the rDCF scheme.

Journal of Science and Technology Research, 2010

Mobile ad hoc networks are highly dynamic networks characterized by the absence of physical infrastructure. In such networks, nodes are able to move, evolve concurrently and synchronize continuously with their neighbours. There have been many studies on modeling and throughput analysis of single-hop 802.11 wireless networks but only a few on the analysis of multi-hop wireless networks. In this paper, Markov chain based models of a collision avoidance MAC protocol for multi-hop wireless ad-hoc networks is employed. These models are used to derive the duration time, transmission probabilities, transition probabilities and steady-state probabilities of the states of node as well as the throughput of MANETs .Simulation results shows that throughput of a MANETs increases with increase in persistent probability, sensing range and length of a DATA frame and also it has a peak value at some point of the persistent probability, sensing range and length of a DATA frame, which is influenced by the number of nodes.