Time-spread multiple-access (TSMA) protocols for multihop mobileradio networks

This paper introduces a novel technique called protocol threading, yielding a deterministic protocol that gives a guaranteed upper bound on the transmission delay of each packet at every node in a multihop mobile network. By eliminating the maximum degree constraint, the new method improves upon existing time-spread multiple-access (TSMA)-type protocols while preserving the advantages of the deterministic operation and topology transparency. We introduce the protocol threading solution, derive the maximum delay bound in a mobile topology, and analyze the performance of the protocol     

A topology transparent link activation protocol for mobile CDMAradio networks

A topology transparent protocol for link activation in mobile CDMA networks is presented. The protocol resolves primary and secondary conflicts, and can easily be adapted to TDMA link activation, as well. The proposed protocol guarantees that each link will be successfully activated at least once in a frame without the need to adjust transmission schedules in mobile environments. Compared to other protocols with guaranteed delivery, the overhead due to the recomputation of transmission schedules is eliminated and, accordingly, transmissions need not be suspended for schedule reorganization. Furthermore, contrary to previously known protocols that adapt to mobility by schedule recomputation, the proposed solution is not subject to a potential catastrophic failure when the rate of topology changes exceeds the rate at which schedules can be readjusted. We prove the correctness and evaluate the efficiency of the new protocol by analytical methods     

Rationale, directions, and issues surrounding high speed networks

An examination is made of the rationale behind the need for ever higher networking speeds, the technological developments that are making them possible on a commercial basis, the directions being taken in their development, and the issues surrounding their construction and use. Roadblocks to providing high-speed networks are discussed. The impact of standardization efforts on development efforts is considered, focusing on the HSC channels, the fiber distributed data interface (FDDI), and metropolitan- and wide-area networks (MANs and WANs). Possibilities for future technologies and architectures are described     

Tractable analytic models of demand assignment protocols innetworks with arbitrary buffer capacity

The authors introduce analytic models for evaluating demand assignment protocols in realistic finite-buffer/finite-station network configurations. A solution for protocols with gated and nongated service disciplines that enables one to model demand assignment protocols as found, for example, in local and metropolitan area networks and in satellite communication systems is presented. A tractable approximate solution based on linear equations whose number is also linear is given. It is demonstrated that in addition to its computational efficiency, the presented approach does not incur a significant penalty in terms of accuracy     

Fair Algorithms for Maximal Link Activation in Multihop Radio Networks

We present a distributed algorithm for obtaining a fair time slot allocation for link activation in a multihop radio network. We introduce the concept of maximal fairness in which the termination of a fair allocation algorithm is related to maximal reuse of the channel under a given fairness metric. The fairness metric can be freely interpreted as the expected link traffic load demands, link priorities, etc. Since respective demands for time slot allocation will not necessarily be equal, we define fairness in terms of the closeness of allocation to respective link demands while preserving the collision free property. The algorithm can be used in conjunction with existing link activation algorithms to provide a fairer and fuller utilization of the channel.     

Voice/data integration on Ethernet — backoff and priority considerations

Astudy of the CSMA/CD protocol as given in the Ethernet specifications, for real time (voice in particular) and mixed voice/data environments is described. The objectives of the study were to predict the Ethernet's behaviour under the current protocols, to point out potential improvements within the realm of the current specifications, and to improve understanding of the network behaviour in these environments. Results are given in terms of relative performance of the various system measures given as a function of system and traffic models. It is shown that the support provided to real time voice on Ethernet strongly depends on the assumptions made with regard to the coexisting data user's traffic and that with certain data traffic patterns the observed voice delay is much worse than previously reported. Finally, it is shown that without violating the Ethernet network specification, voice service can be improved by simple adjustments of the Ethernet retransmission ‘backoff’ algorithm.     

Quadro-Star: a high performance optical WDM star network

This paper proposes an original approach to controlling WDM Passive optical stars, termed queuing arrivals for delayed reception operation (Quadro). In WDM stars the fundamental problem of receiver conflicts leads to severe performance degradation. In current solutions conflicts are prevented by scheduling transmissions or resolved by retransmissions. Both approaches waste bandwidth and involve electronic processing and buffering. The proposed approach is conceptually different in introducing a local conflict resolution mechanism at each receiver incorporating delay lines. This solution brings optical star networks a step closer to an all-optical realization. In addition, it allows an almost total utilization of the channels, as obtainable until now only by TDM control. Contrary to TDM, however, the proposed solution does not suffer performance degradation under heterogeneous traffic conditions and increasing number of nodes. It is thus unique in offering the potential of an all-optical solution providing at the same time high throughput, low delay, small buffer requirements, and robustness under all traffic conditions     

Optimizing the system of virtual paths

The virtual path (VP) concept is known to be a powerful transport mechanism for ATM networks. This paper deals with the optimization of the virtual paths system from a bandwidth utilization perspective. While previous research on VP management has basically assumed that bandwidth in ATM networks is unlimited, emerging technologies and applications are changing this premise. In many networks, such as wireless, bandwidth is always at a premium. In wired networks, with increasing user access speeds, less than a dozen of broadband connections can saturate even a Gigabit link. We present an efficient algorithm that finds a system of VP routes for a given set of VP terminators and VP capacity demands. This solution is motivated by the need to minimize the load, or reduce congestion, generated by the VP's on individual links. A nontrivial performance guarantee is proven for the quality of the proposed solution and numerical results show that the proposed solution carries the potential for a near optimal allocation of VPs     

Design and analysis of very high-speed network architectures

Communication architectures for very-high-speed networks are dealt with. The use of high communication speed increases the ratio between the end-to-end propagation delay and the packet transmission time. This increase restricts the utilization of the high system bandwidth in broadcast channel-based systems, causing a rapid performance deterioration. A communication system architecture characterized by the use of several parallel channels and design of the nodes' channel interface is presented. The channel-division approach is introduced, showing that for a given system bandwidth the total system capacity will be increased by bandwidth division and parallel communication. An analytic model of this system is developed, from which the proposed system's performance is obtained and performance bounds determined for multichannel slotted finite systems. The results show that the architecture has a potential to improve significantly the system performance compared to conventional single-channel-based systems. Furthermore, for a given network configuration an optimal architecture can be found which simultaneously maximizes the system throughput and minimizes the average packet delay     

BlueMesh: Degree-Constrained Multi-Hop Scatternet Formation for Bluetooth Networks

In this paper we describe BlueMesh, a new protocol for the establishment of scatternets, i.e., multi-hop wireless networks of Bluetooth devices. BlueMesh defines rules for device discovery, piconet formation and piconet interconnection so to generate connected scatternets with the following desirable properties. BlueMesh forms scatternets without requiring the Bluetooth devices to be all in each other transmission range. BlueMesh scatternet topologies are meshes with multiple paths between any pair of nodes. BlueMesh piconets are made up of no more than 7 slaves. Simulation results in networks with over 200 nodes show that BlueMesh is effective in quickly generating a connected scatternet in which each node, on average, does not assume more than 2.4 roles. Moreover, the route length between any two nodes in the network is comparable to that of the shortest paths between the nodes.