Time Division Multiple Access Broadcast Research Articles

Heuristic approach for broadcast scheduling, problem in wireless mesh networks

Disasters can be natural and human-initiated events that interrupt the usual functioning of people on a large scale. Region where disasters have occurred causes hazards to the public of that area and to the rescue teams. Disaster causes the damage to the communication network infrastructure also. Once the communication infrastructure is damaged, it is very difficult to the rescue teams to actively involve in relief operation. To handle these hazards, different wireless technologies can be initiated in the area of disaster. This paper discusses the innovative wireless technology for disaster management. Specifically, issues related to the broadcast scheduling problem in wireless mesh network is deployed efficiently during disaster relief are discussed. A domain specific memetic algorithm is proposed for solving the optimum time division multiple access broadcast scheduling problem in wireless mesh networks. The aim is to increase the total number of transmissions in optimized time slot with high channel utilization in a less computation time. Simulation results showed that our memetic algorithm approach to this problem achieves 100% convergence to solutions within reduced computation time while compared to recent efficient algorithms. The results were compared with several heuristic and non-heuristic algorithms for broadcast scheduling problem.

Solving optimum TDMA broadcast scheduling in mobile ad hoc networks: a competent permutation genetic algorithm approach

A competent permutation encoded genetic algorithm (GA) is proposed for solving the optimum time division multiple access (TDMA) broadcast scheduling problem in mobile ad hoc networks. The problem is widely known as non-deterministic polynomial (NP) complete and diverse heuristic algorithms were reported to solve this problem recently. In this study, the GA approach is developed to cooperate with a deterministic greedy-like algorithm to obtain the optimum schedules. The main feature of the proposed GA approach lies in employing a permutation encoding strategy and thus obviates the invalid solutions encountered by the conventional binary encoding scheme. Consequently, the problem search space is reduced to a great extent and the GA becomes more efficient in searching the optimum solutions. A variety of simulation scenarios were conducted to examine the evolutionary behaviour and the scheduling performance of the proposed GA approach. Simulation results suggest that the proposed GA approach exhibits superior search capability in obtaining lower frame length whilst maintaining higher slot utilisation compared with other recently proposed methods.

Topology-transparent time division multiple access broadcast scheduling in multihop packet radio networks

Many topology-dependent transmission scheduling algorithms have been proposed to minimize the time-division multiple-access frame length in multihop packet radio networks (MPRNs), in which changes of the topology inevitably require recomputation of the schedules. The need for constant adaptation of schedules-to-mobile topology entails significant problems, especially in highly dynamic mobile environments. Hence, topology-transparent scheduling algorithms have been proposed, which utilize Galois field theory and Latin squares theory. We discuss the topology-transparent broadcast scheduling design for MPRNs. For single-channel networks, we propose the modified Galois field design (MGD) and the Latin square design (LSD) for topology-transparent broadcast scheduling. The MGD obtains much smaller minimum frame length (MFL) than the existing scheme while the LSD can even achieve possible performance gain when compared with the MGD, under certain conditions. Moreover, the inner relationship between scheduling designs based on different theories is revealed and proved, which provides valuable insight. For topology-transparent broadcast scheduling in multichannel networks, in which little research has been done, the proposed multichannel Galois field design (MCGD) can reduce the MFL approximately M times, as compared with the MGD when M channels are available. Numerical results show that the proposed algorithms outperform existing algorithms in achieving a smaller MFL.

A Five-Phase Reservation Protocol (FPRP) for Mobile Ad Hoc Networks

A new single channel, time division multiple access (TDMA)-based broadcast scheduling protocol, termed the Five-Phase Reservation Protocol (FPRP), is presented for mobile ad hoc networks. The protocol jointly and simultaneously performs the tasks of channel access and node broadcast scheduling. The protocol allows nodes to make reservations within TDMA broadcast schedules. It employs a contention-based mechanism with which nodes compete with each other to acquire TDMA slots. The FPRP is free of the "hidden terminal" problem, and is designed such that reservations can be made quickly and efficiently with negligible probability of conflict. It is fully-distributed and parallel (a reservation is made through a localized conversation between nodes in a 2-hop neighborhood), and is thus scalable. A "multihop ALOHA" policy is developed to support the FPRP. This policy uses a multihop, pseudo-Bayesian algorithm to calculate contention probabilities and enable faster convergence of the reservation procedure. The performance of the protocol, measured in terms of scheduling quality, scheduling overhead and robustness in the presence of nodal mobility, has been studied via simulations. The results showed that the protocol works very well in all three aspects. Some future work and applications are also discussed.

A new optical time-division multiple-access broadcast network based on multistar topology

A new optical time division multiple-access (OTDMA) broadcast network is proposed, in which two wavelengths are used to carry OTDMA and optical clock signals, respectively. At each OTDMA receiver, the slot/phase synchronization is feasibly achieved by using simple optical delay lines to process the separated clock and OTDMA signals. The detailed hardware design of the proposed network is also described. It is shown that using the newly proposed technique one can build flexible multistage broadcast networks based on star topology.

Self-synchronised all-optical time-division multiple-access broadcast network

A novel all-optical TDMA network is proposed, in which two wavelengths are used to carry optical TDMA and clock signals, respectively. The proposed network can support multirate data communications by using simple optical delay-line processors. The architecture for all-optical TDMA receivers is presented. The proposed technique can be used to build flexible multistar broadcast networks.