Multi-channel Protocol Research Articles

Operation, system architectures, and physical Layer design considerations of distributed MAC protocols for UWB

Impulse-based ultra wideband (I-UWB) is an attractive radio technology for large ad hoc and sensor networks due to its robustness to harmful multipath effects, sub-centimeter ranging ability, simple hardware, and low radiated power. To scale to large sizes, networks often implement distributed medium access control (MAC) protocols. However, most MAC protocols for I-UWB are centralized, and they target small wireless personal area networks and cellular networks. We propose three distributed MAC protocols suitable for I-UWB. Two multichannel protocols, called multichannel pulse sense multiple access (M-PSMA) and multichannel ALOHA achieve high aggregate throughput. A busy-signal protocol, called busy-signal multiple access (BSMA), reduces the energy wasted from re-transmitted packets. This paper describes the three protocols in terms of the protocol's operation, the supporting system architecture, and the I-UWB physical layer. Physical layer simulations confirm the feasibility of implementing the proposed systems and also provide parameters for network simulations. Network simulations show that the throughput of M-PSMA exceeds that of a centralized time-division multiple-access protocol and that the energy efficiency of BSMA far surpasses that of other distributed protocols.

Theoretical Analysis and Performance of NC-PRMA Protocol for Multichannel Wireless Networks

In this paper, we analyze the effect of duplexing schemes on the throughput and the average packet dropping probability of a new multichannel wireless access protocol which allows for non-collision packet reservation multiple access with multiple channel (NC-PRMA/MC). N C equal-capacity, orthogonal, traffic channels are shared by M mobile users on the uplink. Transmission attempts on the uplink are made by using time-frequency signaling in every frame, which enables transmission attempts of mobile users to be conveyed to the base station without collisions. Two kinds of duplexing schemes, frequency division duplexing and shared time division duplexing, are considered in the performance analysis. Using a discrete-time Markov chain analysis, we derive the analytic expressions for the average per channel throughput and the average packet dropping probability. Computer simulation results verify the analysis. Analytical evaluation and computer simulation show that NC-PRMA/MC with shared time division duplexing improves the channel capacity, which approaches the theoretical upper bound.

Load-Balancing Routing in Multichannel Hybrid Wireless Networks With Single Network Interface

A hybrid wireless network is an extension of an infrastructure network, where a mobile host may connect to an access point (AP) using multihop wireless routes, via other mobile hosts. The APs are configured to operate on one of multiple available channels. Mobile hosts and wireless routers can select its operating channel dynamically through channel switching. In this environment, a routing protocol that finds routes to balance load among channels while maintaining connectivity was proposed. The protocol works with nodes equipped with a single network interface, which distinguishes the work with other multichannel routing protocols that require multiple interfaces per node. The protocol discovers multiple routes to multiple APs, possibly operating on different channels. Based on a traffic load information, each node selects the "best" route to an AP and synchronizes its channel with the AP. With this behavior, the channel load is balanced, removing hot spots and improving channel utilization. The protocol assures every node has at least one route to an AP, where all intermediate nodes are operating on the same channel. The simulation results show that the proposed protocol successfully adapts to changing traffic conditions and improves performance over a single-channel protocol and a multichannel protocol with no load balancing.

Multichannel mesh networks: challenges and protocols

Supporting high throughput is an important challenge in multihop mesh networks. Popular wireless LAN standards, such as IEEE 802.11, provision for multiple channels. In this article, we consider the use of multiple wireless channels to improve network throughput. Commercially available wireless network interfaces can typically operate over only one channel at a time. Due to cost and complexity constraints, the total number of interfaces at each host is expected to be smaller than the total channels available in the network. Under this scenario, several challenges need to be addressed before all the available channels can be fully utilized. In this article, we highlight the main challenges, and present two link-layer protocols for utilizing multiple channels. We also present a new abstraction layer that simplifies the implementation of new multichannel protocols in existing operating systems. This article demonstrates the feasibility of utilizing multiple channels, even if each host has fewer interfaces than the number of available channels.

Markovian receiver collision analysis of high-speed multi-channel networks

Two synchronous transmission multi-channel multi-access protocols for high-speed network architecture are studied in this paper. Analytic discrete time Markovian models are developed for finite number of stations and finite number of channels for the symmetric and asymmetric access rights proposed protocols. The effect of receiver collision phenomenon is examined and analysed on the performance measures evaluation and estimated by the probability of packet rejection at destination. Also, numerical results are presented for comparison for various numbers of data channels and stations. Copyright © 2005 John Wiley & Sons, Ltd.

Multichannel Video and IP Signal Multiplexing System Using CWDM Technology

This paper describes how coarse wavelength-division multiplexing can realize a multiplexed multichannel video and Internet protocol (IP) system. In the proposed configuration, each signal is optically amplified separately to extend the service area. The IP signals are boosted by cost-effective erbium-doped fiber amplifiers, which have a simple configuration optimized for single-channel use. Two multiplexer/demultiplexer configurations are described. The proposed configurations yield a contents distribution network that offers bidirectional IP service in addition to the multichannel video service, which is transmitted as an analog signal. This paper presents an experiment that confirms the feasibility of this proposed system.

An unslotted multichannel channel-access protocol for distributed direct-sequence networks

A multichannel reservation-based channel-access protocol is investigated in this paper. The available system bandwidth is divided into distinct frequency channels. Under the protocol, one channel (the control channel) is used to exchange reservation messages and the remaining channels (the traffic channels) are used for information-bearing traffic. The performance of this scheme is compared to that of a single-channel reservation-based protocol. A simple contention-based slotted-Aloha protocol is also considered. Performance results take into account the effects of multiple-access interference on acquisition and packet errors. Results show that the reservation-based approach is advantageous under conditions of high traffic. In addition, a pacing mechanism that mitigates multiple-access interference and promotes fairness is described, and results are presented that demonstrate its effectiveness.

Throughput evaluation of multichannel slotted Aloha-type protocols with receiver collisions

The problem of receiver collisions in multichannel multiaccess communication systems is studied in this paper. A rigorous method is developed for the analytic solution of throughput performance assuming receiver buffer with a capacity of one packet. We calculate the average rejection probability at the destination of a packet in order to estimate the effect of receiver collisions. The evaluations are carried out for multichannel slotted Aloha-type protocols with Poisson arrivals and finite population. Also numerical results are showing the throughput reduction as it compared with the protocol case without receiver collisions.

MultiS-Net: A high-capacity, packet-switched, multichannel, single-hop architecture and protocol for a local lightwave network

A variety of multichannel single-hop network architectures and protocols have recently been proposed to exploit the vast capacity of fiber-optics which can well exceed the maximum electronic speed limit. Our MultiS-Net proposal is a new multichannel, single-hop architecture and protocol for a local network which provides packet-switched services to a large number of users connected to a multichannel broadcast medium. A separate channel, called control channel, is established to coordinate data packet transmissions on the other channels (called data channels). To allow low network interfacing costs, each node.in MultiS-Net is only equipped with a single tunable transmitter and a single tunable receiver, both of which are responsible for data channel access as well as control channel access. Without a separate transmitter and a separate receiver dedicated to the control channel, a node cannot have global knowledge of the network status all the time. Hence, global reservation is infeasible here, and all previously proposed schemes with the same low-cost network interface as in MultiS-Net fail to achieve a system throughput as high as those achieved by global-reservation schemes. MultiS-Net successfully incorporates a simple medium access mechanism, which can also achieve high system throughput. In addition, MultiS-Net can accommodate a variable number of nodes as well as time-varying load; typically, however, the number of nodes may be much larger than the number of available data channels. We analyze the performance of MultiS-Net by first constructing a multidimensional Markov chain. Then, the equilibrium point analysis (EPA) technique is adopted to obtain the average data packet delay and system throughput, which are verified by simulation. Numerical results from both the analytical model and simulations are presented, and the impact of various parameters on the system performance is discussed. Nearly-full utilization of total data channel bandwidth can be achieved under proper configurations of system parameters.

Stability and throughput optimization of multichannel slotted non-persistent CSMA protocol

This paper describes two protocols suitable for a multichannel, multiaccess slotted non-persistent CSMA environment for infinite population, analyses their stability and examines their throughput optimization. The common sensing multichannel slotted non-persistent CSMA (CSCSMA) protocol is an extension of the slotted single channel non-persistent CSMA protocol with an appropriate policy for the selection of the channel in which a station (re)transmits. This policy restricts the control information among the stations, and consequently reduces the cost of the station interface. Pakes's Lemma criteria are applied to define sufficient conditions for ergodicity of the Markov chain, which describes the evolution of the busy station population, and to specify regions in which the multichannel system is stable. Control parameters are the retransmission probabilities. Optimization rules are derived which show that the optimal retransmission probabilities may be expressed as a function of the number of busy stations. The separate sensing multichannel slotted non-persistent CSMA protocol (SSCSMA), using a different policy, distinguishes the channels into two groups: the retransmission channel group devoted in collision resolution; and the transmission channel group for the access of free stations. Stability regions are defined using the results for CSCSMA, and rules for optimal allocation of channels among the two groups are derived for improvement of system performance.

Packet reservation protocols for multichannel satellite networks

Owing to system economics, many satellite data networks have star configurations, with low cost user terminals communicating with high performance hub earth stations over inbound multiaccess channels and outbound broadcast channels. The inbound channel data rate is often limited by the power budget, so that multiple satellite channels are required to accommodate the overall traffic in a large network. Most packet multiaccess protocols previously considered, when applied to multichannel satellite networks, enable distinct groups of users to share individual channels. In contrast, this paper presents a new class of multichannel reservation protocols (MRPs) which improves channel utilisation by enabling complete sharing of all channels among all users. For good throughput efficiency and reduced delay, the MRPs employ slotted random access with immediate retransmissions for first-packet and reservation request transmissions, and reservation of consecutive time slots for transmissions of remaining packets in multipacket messages. Delay throughput characteristics are derived under steady state conditions. Numerical results show that the MRPs achieve higher throughput capacity than random access protocols and lower average delay than other reservation protocols.

Multichannel slot reservation protocol for use on WDM optical fibre LAN

A novel multichannel slot reservation protocol is introduced for application on an optical fibre local area network (LAN) employing wavelength division multiplexing (WDM). The multichannel protocol is shown to demonstrate considerable performance advantages, when compared to the single channel protocol, particularly under asymmetric traffic loading.

On full utilization of multi-channel capacity with priority protocol

To resolve multi-user conflict on a communication channel, a slotted access protocol selects one of the intended messages for transmission in each transmission session. For an easily implementable protocol, often the process of selecting a message for transmission is logically equivalent to the selection according to a predetermined priority ordering among all possible messages. Let a protocol of this characteristic be called a priority protocol. Under a multi-channel priority protocol, all intended messages simultaneously contend for the transmission over every individual channel. The multi-channel capacity is fully utilized when every channel transmits a different message. When the quantity of intended messages is large enough, it is possible to associate each channel with a different priority ordering on messages so that the multi-channel capacity is always fully utilized. This article determines the level of the quantity of intended messages that is necessary and sufficient for this purpose.

Constructing real-time multi-channel protocols

In a previous work, a method has been suggested to construct logically correct communication protocols for a closed system of two finite-state machines, communicating over an arbitrary number of rendez-vous channels and/or reliable, unbounded FIFO channels with unknown transit delays, ranging from zero to any finite amount of time. The method combines step-wise refinement and phase-by-phase construction. The emphasis is laid upon prevention of overspecification. In the present paper, the central part of the method is adapted to cover the quantitative aspect of time. It is suitable for a system with a global clock and takes into consideration any known lower of upper limits of transit delays.

Wavelength division multiple access on a high-speed optical fibre LAN

Abstract A multichannel medium access control protocol suitable for implementation on a wavelength division multiplexed optical fibre LAN is discussed. Particular emphasis is placed on the mean delay against network throughput performance at individual channel transmission rates of 100 Mbit/s. The protocol is based on a token passing arbitration policy which dynamically allocates both the token and the data to individual wavelength multiplexed channels. An improved performance is demonstrated in comparison with alternative conventional approaches operating at an equivalent overall network transmission rate.

Multichannel reservation protocol for packet multiple-access communications

An efficient protocol well suited for the transmission of variable length messages over a group of parallel channels is described. The protocol is applicable to star networks with inbound multiple-access and outbound broadcast channels. Throughput capacity of the inbound channels is analysed and optimised with respect to message length and packet overhead.

Piggybacked token-passing access protocol for multichannel optical fibre LANs

A novel Medium Access Control protocol suitable for use with multichannel optical fibre Local Area Networks employing Wavelength Division Multiplexing is described. It is based on token-passing channel arbitration in which all channels may be available to carry all of data, acknowledgement and token packets. To increase bandwidth utilization the protocol has the facility to piggyback data packets with the token at high traffic loads. Expressions are derived for the mean delay against network throughput performance for the protocol using data traffic generated with a Poisson distribution, and symmetrically disposed over the network nodes. It is demonstrated that the multichannel protocol gives a substantial improvement in network throughput performance compared with that of a conventional single channel protocol employing the same overall data transmission rate.

Performance investigation of a token passing access protocol for a multichannel optical fibre LAN

An alternative approach to multichannel local area network access is described. The new multichannel access scheme or protocol is based on a token passing arbitration policy. It is specifically intended for use with a starconfigured optical fibre LAN employing wavelength division multiplexing technology in order to provide a multichannel transmission medium. The multichannel network architecture comprises a single reservation channel and several equivalent speed data channels. Delay versus throughput performance characteristics for the network obtained by both analysis and discrete event simulation are shown. The multichannel token passing protocol is found to significantly improve these characteristics in comparison with a conventional single channel token passing approach using the same overall network transmission rate (i.e. the sum of the individual channel bit rates in the multichannel case). Furthermore, when the end-to-end propagation delay for an individual channel on the network becomes large, the multichannel token passing protocol is shown to exhibit an improved delay versus throughput performance over a multichannel protocol employing carrier sense multiple access with collision detection.

A multibus train communication (AMTRAC) architecture for high-speed fiber optic networks

A multibus train (ordered demand assignment) communication architecture, using the AMTRAC protocol (for efficient utilization of fiber-optic-based very-high-speed networks) is presented. Taking advantage of the emerging WDM (wavelength-division multiplexing) and FDM (frequency-division multiplexing) technologies, the proposed solution introduces a coordinated multichannel control combining the performance advantages of two known approaches for high-speed communication: multichannel and train protocols. As a result an AMTRAC-based high-speed network achieves channel utilization significantly higher than previous approaches. For a network consisting of N stations, with propagation delay to packet transmission time ratio given by a, the AMTRAC architecture reaches a capacity of 1/(1+a/N/sup 2/). >