TRACE: a family of protocols for energy-efficient real-time data communicaiton in a mobile ad-hoc network

SH-TRACE

Single-hop Time Reservation Using Adaptive Control For Energy Efficiency (SH-TRACE) is a time frame based MAC protocol designed primarily for energy-efficient reliable real-time voice packet broadcasting in a single-hop infrastructureless radio network, but it can also be used for energy efficient asynchronous and unicast data traffic.  SH-TRACE includes the following features:

• Dynamic transmission scheduling and receiver-based soft clustering via data summarization to support dynamic nodes and dynamic loads
• Coordinator switching for even distribution of the energy load among the nodes
• Automatic coordinator backup to guarantee the network is functional independent of individual node failure
• Information summarization prior to data transmission to prevent nodes from wasting considerable amount of energy receiving unwanted data packets
• Multiple priority levels to enable the network to support multiple levels of QoS
• Minimum bandwidth and maximum delay guarantees for voice packets  

MH-TRACE

Multihop time reservation using adaptive control for energy efficiency (MH-TRACE) is a medium access control (MAC) protocol that combines advantageous features of fully centralized and fully distributed networks for energy-efficient real-time packet broadcasting in a multihop radio network. We introduce a novel clustering algorithm that dynamically organizes the network into two-hop clusters. MH-TRACE clusters are just for coordinating channel access and minimizing interference; thus, ordinary nodes are not static members of any cluster. Time is organized into cyclic superframes, which consist of several time frames, to support reservation-based periodic channel access for real-time traffic. Each clusterhead chooses the frame with least interference based on its own measurements for the operation of its cluster. Energy dissipation for receiving unwanted or collided data packets or for waiting in idle mode is avoided through the use of information summarization packets sent prior to the data transmissions by the source nodes. Through the use of transmission schedules within each cluster, managed by the clusterheads, intracluster data collisions are completely eliminated and intercluster collisions are minimized. We investigated MH-TRACE through extensive simulations and theoretical analysis. Our results show that MH-TRACE outperforms existing distributed MAC protocols like IEEE 802.11 and sensor MAC, in terms of energy efficiency and throughput, approaching the theoretical maximum throughput and theoretical minimum energy dissipation.

NB-TRACE

Network Wide Broadcasting Through Time Reservation Using Adaptive Control For Energy Efficency (NB-TRACE) is another member of TRACE family. NB-TRACE is an energy-efficient network-wide voice broadcasting architecture for mobile ad hoc networks. In the NB-TRACE architecture, the network is organized into overlapping clusters, where the clusterheads create a non-connected dominating set. Channel access is regulated through a locally maintained distributed TDMA scheme. The first group of packets of a broadcast session is broadcasted through blind flooding. Each data rebroadcast includes an implicit acknowledgement to the upstream node. Nodes that do not get acknowledgement for a predetermined time, except the clusterheads, cease to rebroadcast, which prunes the redundant retransmissions. The distributed connected dominating set formed through this basic algorithm is broken in time due to node mobility. The network responds to the broken links through passive and active clusterhead data transmission monitoring to ensure the maintenance of the connected dominating set. We compared NB-TRACE with flooding and gossiping using the MH-TRACE, IEEE 802.11, and SMAC medium access control protocols through ns-2 simulations. Our results show that NB-TRACE outperforms other network/MAC layer combinations in terms of energy efficiency, packet delivery ratio, jitter, and number of rebroadcasts. For more information about this project, contact Bulent Tavli .

MC-TRACE

Multicasting Through Time Reservation Using Adaptive Control for Energy Efficiency (MC-TRACE) is the final member of the TRACE family. MC-TRACE is an energy-efficient voice multicasting architecture for mobile ad hoc networks. MC-TRACE is a monolithic design, where the medium access control layer functionality and network layer functionality are performed by a single integrated layer. The basic design philosophy behind the networking part of the architecture is to establish and maintain a multicast tree within a mobile ad hoc network using broadcasting to establish the desired tree branches and pruning the redundant braches of the multicast tree based on feedback obtained from the multicast leaf nodes. Energy efficiency of the architecture is partially due to the medium access part, where the nodes can switch to sleep mode frequently; and partially due to the network layer part where the number of redundant data retransmissions and receptions are mostly eliminated. Furthermore, MC-TRACE achieves high spatial reuse efficiency by keeping the number of nodes taking part in multicasting operation minimal. We evaluated the performance of MC-TRACE through ns simulations and compared with flooding. Our results show that packet delivery ratio performance, energy efficiency and spatial reuse efficiency of MC-TRACE is superior to those of flooding. For more information about this project, contact Bulent Tavli .

Coordinated vs. Non-Coordinated

We investigated the effects of channel noise on the performance of coordinated and non-coordinated MAC protocols. Comparative evaluations of these protocols under a perfect channel assumption have shown that coordinated MAC protocols, which regulate channel access locally, outperform non-coordinated channel access schemes in terms of energy efficiency and throughput. However, coordinated MAC protocols are more vulnerable than non-coordinated MAC protocols to channel noise due to their dependence on the robustness of the control traffic. In order to observe the degradation in performance of a coordinated MAC protocol (MH-TRACE), we investigate the impact of losing control packets. Furthermore, the performance in terms of throughput, delay, and energy efficiency of both coordinated (MH-TRACE) and non-coordinated (IEEE 802.11) MAC protocols is explored using a general error model that takes into account the length of the packets. Our results show that despite its higher level of vulnerability, the coordinated MAC protocol's performance is superior to the performance of the non-coordinated MAC protocol even when error rates are high.

This work was supported in part by the University of Rochester Center for Electronic Imaging Systems and in part by Harris Corporation, RF Communications Division. For further information please contact with Tolga Numanoglu.