TDMA scheduling design of multihop packet radio networks based on latin squares

Many transmission scheduling algorithms have been proposed to maximize the spatial reuse and minimize the time division multiple access (TDMA) frame length in multihop packet radio networks. Almost all existing algorithms assume exact network topology information and require recomputations when the network topology changes. In addition, existing work focuses on single channel TDMA systems. In this paper, we propose a multichannel topology-transparent algorithm based on latin squares. This algorithm has the flexibility to allow the growth of the network, i.e., the network can add more mobile nodes without recomputation of transmission schedules for existing nodes. At the same time, a minimum throughput is guaranteed. We analyze the efficiency of our algorithm, and examine the topology-transparent characteristics and the sensitivity on design parameters by simulation.published_or_final_versio

An optimal topology-transparent scheduling method in multihop packet radio networks

Many transmission scheduling algorithms have been proposed to maximize the spatial reuse and minimize the time-division multiple-access (TDMA) frame length in multihop packet radio networks. Almost all existing algorithms assume exact network topology information and do not adapt to different traffic requirements. Chlamtac and Farago proposed a topology-transparent algorithm. Following their approach, but with a different design strategy, we propose another algorithm which is optimal in that it maximizes the minimum throughput. We compare our algorithm with that of Chlamtac and Farago's and with the TDMA algorithm, and find that it gives better performance in terms of minimum throughput and minimum and maximum delay times. Our algorithm requires estimated values of the number of nodes and the maximum nodal degree in the network. However, we show that the performance of our algorithm is insensitive to these design parameters. © 1998 IEEE.published_or_final_versio

Optimal resource allocation for transmitting network information and data in wireless networks

The capacity of wireless networks is greatly affected by the available information on network states, such as network topology, channel state, and traffic information. Previous research has estimated the capacity of wireless networks by assuming that each node in the network can obtain precise network information. However, in reality, precise network information may not be readily available, and it may require a large amount of bandwidth resource to maintain accurate network information, thus reducing the net data rate. In this paper, we study the tradeoff between network performance improvement and the communication overhead of transmitting network information. To do so, we first determine the resource required to transmit network information reliably. A channel model is presented for the transmission of network information packets, and the network protocols are modeled as coding schemes. An information- theoretic method is used to obtain the lower bound on the resource required to maintain accurate network information. We use the result to find the optimal allocation of resource between network information transmission and data transmission so as to maximize the net data rate. The model can also be used to derive the upper bound on wireless network performance for topology-transparent algorithms. ©2010 IEEE.published_or_final_versionThe IEEE International Conference on Communications (ICC) 2010, Cape Town, South Africa, 23-27 May 2010. In Proceedings of the IEEE ICC, 2010, p. 1-

Multichannel time-spread scheduling: a new approach to handling heavy traffic loads in ad hoc networks

Abstract — Wireless mobile networks that do not have infras-tructure or centralized administration, known as the ad hoc networks, have received considerable attention in the last few years. The salient characteristics of such networks –time-varying topology and lack of centralized control design – have made medium access control design more complicated and challenging, which is particularly when multiple channels are employed. Recently, many multichannel transmission protocols, such as Collision-Avoidance Transmission Scheduling (CATS), have been investigated for their higher efficiency although their problems are abundant. In this paper, we propose a new protocol, namely, MultichAnnel Time-spread Scheduling (MATS), to improve the throughput performance under heavy traffic loads. In MATS, nodes with transmission requests are divided into three groups, and carry out channel reservations in parallel with a short overhead. We carry out simulation study and the results show that the performance of this protocol under high traffic loads is significantly improved. I

CROSS-LAYER SCHEDULING PROTOCOLS FOR MOBILE AD HOC NETWORKS USING ADAPTIVE DIRECT-SEQUENCE SPREAD-SPECTRUM MODULATION

We investigate strategies to improve the performance of transmission schedules for mobile ad hoc networks (MANETs) employing adaptive direct-sequence spread-spectrum (DSSS) modulation. Previously, scheduling protocols for MANETs have been designed under the assumption of an idealized, narrowband wireless channel. These protocols perform poorly when the channel model incorporates distance-based path loss and co-channel interference. Wideband communication systems, such as DSSS systems, are more robust in the presence of co-channel interference; however, DSSS also provides multiple-access capability that cannot be properly leveraged with a protocol designed for narrowband systems. We present a new transmission scheduling protocol that incorporates link characteristics, spreading factor adaptation, and packet capture capability into scheduling and routing decisions. This provides greater spatial reuse of the channel and better adaptability in mobile environments. Simulation results demonstrate the merits of this approach in terms of end-to-end packet throughput, delay, and completion rate for unicast traffic. We also discuss two variations of the protocol: one provides a method for enhancing the network topology through exchange of local information, and the other leverages multi-packet reception (MPR) capability to enhance the network topology. We show that each approach is useful in networks with sparse connectivity. We conclude by studying the capacity of the networks used in previous sections, providing insight on methods for realizing further performance gains