Demand Assignment Multiple Access Protocols Research Articles

Random access schemes for satellite networks, from VSAT to M2M: a survey

SummaryIn this survey paper, we review the random access (RA) techniques with particular emphasis on the issues and the possible solutions applicable to satellite networks. RA dates back to the 1970s when the ALOHA protocol was developed to solve the problem of interconnecting university computers located in different Hawaiian islands. Since then, several evolutions of the ALOHA protocol have been developed. In particular, solutions were devised to mitigate the problem of packet collisions severely degrading the RA protocols performance. The approach followed for many years has been to avoid the occurrence of collisions rather than solving them. More recently, techniques tackling the RA packet collision problem have appeared triggered by the need of improving RA performance in satellite and terrestrial wireless networks. In particular, satellite networks large propagation delay does not allow the adoption of enhanced terrestrial RA techniques based on channel sensing. Adopting conventional demand assignment multiple access protocols is not suitable for supporting a large number of sensors or devices transmitting small‐size low duty cycle packets as required for machine‐to‐machine communications. This provided the stimulus to exploit successive interference cancelation schemes to solve packet collision issues. The use of successive interference cancelation in RA is relatively new and has opened up a promising research area. We provide an extensive review of recent high‐performance RA techniques achieving more than three orders of magnitude throughput increase compared with the original ALOHA at low packet loss rate. In this survey, we cover both slotted and unslotted techniques. Finally, we review the use of RA in satellite systems and related standards including recent proposals for machine‐to‐machine applications. Copyright © 2016 John Wiley & Sons, Ltd.

Performance Measures Of Wireless Protocols For Atm Networks

The concept of wireless ATM is now being actively considered as a potential framework for nextgeneration wireless communication networks capable of supporting integrated multimedia services with different QoS requirements. Several key subsystem design issues for wired ATM and wireless networks needs to be readdressed in the scope of the wireless ATM, which has the capability to extend the statistical multiplexing of wired ATM network into the wireless medium. One of the key subsystem issues is the development of appropriate medium access control (MAC) protocol. The extension of the ATM network into wireless environment faces many interesting problems. The original ATM network was designed for high speed, noiseless, and reliable channels. None of these characteristics are applicable to the wireless channel. One of the critical aspects of a wireless ATM network is the Medium or Multi Access Control (MAC) Protocol used by the Mobile station (MS) to request service from the BS, which has to consider the Quality of Service (QoS) of the specific applications. This paper analyses recently proposed MAC protocols, particularly those of Demand Assignment Multiple Access protocols using TDMA technique with Frequency Division Duplex (FDD). It also gives performance measures of two best suited protocols for wireless network environment Distributed Queuing Request Update Multiple Access (DQRUMA) protocol and Adaptive Request Channel Multiple Access (ARCMA) protocol.

A predictive demand assignment multiple access protocol for Internet access over broadband satellite networks

AbstractMedium access control (MAC) protocol is responsible for wireless resource management, which is crucial to satellite communication. To enhance the performance of broadband satellite networks, the application characteristics should be considered in the design of the MAC protocol. With the rapid expansion of Internet applications and the attractiveness of high speed Internet access via broadband satellite networks, it becomes an attractive objective to take into account the self‐similar nature of Internet traffic in MAC protocol designs. This paper presents a novel predictive demand assignment multiple access (PRDAMA) protocol for packet communications over broadband satellite networks. PRDAMA allocates free bandwidth resources by estimating the positive varying trend of the Internet traffic to facilitate prediction of the bandwidth requirements of the earth stations. Simulation results demonstrate that PRDAMA achieves a lower average delay and delay jitter compared with other DAMA protocols under highly bursty traffic due to its accurate traffic trend prediction. With less bursty traffic, PRDAMA still performs better than the other DAMA protocols under a heavy traffic load. Copyright © 2003 John Wiley & Sons, Ltd.

Analysis of a random-access protocol under long-range-dependent traffic

ALOHA-type random-access protocols have been used as access-control protocols in wireline and wireless, fixed and mobile, multiple-access communications networks. They are frequently employed by the control and signaling subsystem of demand-assigned multiple-access protocols to regulate the sharing of a multi-access communications channel. The correct design and sizing of the random-access operated control/signaling channel is critical in determining the performance of these networks. Excessive delays in the transport of signaling messages (due to too many collisions and retransmissions) lead to unacceptable session-connection setup times. This is of particular concern when the message traffic is highly bursty. We investigate the performance behavior of a random-access protocol when loaded by bursty traffic processes. The latter often exhibit long-range dependence (LRD). We model the LRD traffic flows as multiplicative multifractal processes. The random-access protocol is modeled as an ALOHA channel with blocking. The burstiness of the traffic processes, rather than their LRD character, is the essential element determining the performance behavior of the protocol. When the loading-traffic process is not very bursty, the performance of the random-access channel can be even better than that exhibited under Poisson traffic loading; otherwise, performance degradation is noted. We demonstrate the impact of the selection of the protocol-operational parameters in determining the effective performance behavior of the random-access protocol.

An Interval-Based Scheduling Algorithm for Optical WDM Star Networks

This paper considers scheduling algorithms for multiple access protocols associated with wavelength division multiplexed (WDM) multi-channel optical networks based on the star topology. To share the available channels among nodes, several demand assignment multiple access protocols based on reservation schemes have been proposed. The core of such reservation-based protocols is the scheduling algorithm, which allocates channels and time slots to the nodes based on traffic demand. The key objectives of the scheduling algorithm design are maximization of network utilization and minimization of packet delay. There is a trade-off between these two requirements: it takes more computation time to achieve a better utilization, which in turn will increase packet delay. This trade-off directly affects the overall network performance. Another important requirement is the consideration of transceiver tuning latencies. In this paper, we propose an on-line scheduling algorithm called OIS (On-line Interval-based Scheduling) to balance these requirements and increase network throughput. We also require that the scheduling algorithms be simple so that hardware implementation is feasible to reduce overall delay. We compare our scheduling algorithm to the Transmission Assignment Algorithm (TAA) studied by Borella and Mukherjee (1996); and to a matrix decomposition algorithm studied by Sivalingam and Wang (1996). We show that our algorithm, although suffering from small utilization loss, requires significantly less computation time and results in higher network throughput. In particular, for higher network speeds such as 2.4 Gbps per channel, the potential improvement using our algorithm is substantial. We also provide conditions when either protocol performs better compared to the other.

Channel access and interference issues in multi-code DS-CDMA wireless packet (ATM) networks

Multi-Code Direct-Sequence Code-Division-Multiple-Access (MC-CDMA) has been proposed as a flexible multiple access scheme for wireless packet networks that support a large variety of mobiles with different and even time-varying rates. Using MC-CDMA, traffic streams with significantly different transmission rates can be easily integrated into a unified architecture, with all the transmissions occupying the same bandwidth and having the same spread spectrum processing gain. In this paper, we address medium-access and interference issues in MC-CDMA wireless packet networks. For medium access, we propose and study Multi-Code CDMA (MC-CDMA) with Distributed-Queueing Request Update Multiple Access (DQRUMA) to form a unified bandwidth-on-demand fair-sharing platform for multi-rate wireless services. DQRUMA is an efficient demand-assignment multiple access protocol for wireless access and scheduling. Pseudo-Noise (PN) codes (primary codes) and optimal power levels are allocated to the mobiles on a slot-by-slot basis, and a Maximum Capacity Power Allocation (MCPA) criterion exploits the sub-code concatenation property of the MC-CDMA transmission. Simulation results show that the system provides close to ideal-access performance for multi-rate mobiles, both with homogeneous traffic characteristics and with a mix of heterogeneous traffic characteristics. Finally, we analyze the effects of MC-CDMA intercell interference on the reverse link (i.e., mobile to cell site) and investigate interference reduction by using the Maximum Capacity Power Allocation (MCPA) criterion. Our results show significant reduction in reverse-link MC-CDMA intercell interference is possible using the MCPA criterion.

An efficient demand-assignment multiple access protocol for wireless packet (ATM) networks

In a wireless packet (ATM) network that supports an integrated mix of multimedia traffic, the channel access protocol needs to be designed such that mobiles share the limited communications bandwidth in an efficient manner: maximizing the utilization of the frequency spectrum and minimizing the delay experienced by mobiles. In this paper, we propose and study an efficient demand-assignment channel access protocol, which we call Distributed-Queueing Request Update Multiple Access (DQRUMA). The protocol can be used for a wide range of applications and geographic distances. Mobiles need to send requests to the base station only for packets that arrive to an empty buffer. For packets that arrive to a non-empty buffer, transmission requests are placed collision-free by piggybacking the requests with packet transmissions. The simulation results show that even with the “worst possible” traffic characteristics, the delay-throughput performance of DQRUMA is close to the best possible with any access protocol. In addition, explicit slot-by-slot announcement of the “transmit permissions” gives the base station complete control over the order in which mobiles transmit their packets. This important feature helps the base station satisfy diverse Quality-of-Service (QoS) requirements in a wireless ATM network.

A modified PDAMA protocol for mobile satellite communication systems

Random multiple access and reservation multiple-access protocols which are currently employed in most satellite communication systems have some merits and demerits according to the type of users and traffic. A modified packet demand assignment multiple access (PDAMA) protocol with better characteristics is proposed and analyzed. Using simulation with approximate analysis, the performance of the modified PDAMA is compared with that of a modified random-access protocol as well as the original PDAMA in terms of delay and throughput. For small packet arrival rate, the performance of the proposed access protocol is shown to be similar to that of the modified random-access protocol, and better than that of the PDAMA protocol. While the packet arrival rate increases, the performance of the proposed access protocol is improved greatly compared with that of the PDAMA protocol.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Mobile radio group communications by satellite

Mobile radio group communications enable a closed group of users to communicate among themselves using push-to-talk (PTT), half duplex transmissions, such that one's transmission is received by all. New protocol designs are presented which support group communications over mobile satellite systems. A new demand assignment multiple access (DAMA) protocol is necessitated by the inappropriateness of call-based channel assignments. Channels are assigned to individual user-groups engaged in active conversations. As members of a user-group contend for access to the assigned channel, access control by the usual manual methods is ineffective due to the very long round trip delay. A novel signaling protocol which automates access control is proposed. Carrier sensing, signal capture, and collision detection are employed to minimize access contentions. The throughput and holding time of the assigned channel are analyzed. Numerical results show that the access control protocol improves the capacity of the assigned channel by up to 65%. >

Protocol design for mobile radio group communications over satellite

A protocol design for a mobile radio service supporting half-duplex push-to-talk voice communications over mobile satellite systems is presented. The service enables a closed group of mobile radio users to communicate among themselves, so that a transmission from any user is received by all. A key issue is the efficient utilization of satellite channels. Demand-assignment multiple access (DAMA) is employed to allocate channels only to those user groups in active sessions of conversations. Owing to the unique characteristics of the half-duplex point-to-multipoint group communications, a new DAMA protocol is proposed for this service. Within a channel assigned to a user group, access contentions exacerbated by very long round-trip delay can occur. A signaling protocol is devised to arbitrate access contentions so as to improve the utilization of the assigned channel. The proposed access control protocol offers 65% or 18% improvement in throughput capacity compared to manual carrier-sensed access without and with collision detection, respectively. >

Management of transponder resources in mobile satellite systems

Allocation of L-band spectrum for land mobile satellite (MSAT) services in Mobile-WARC-87 paves the way for the introduction of such services in the early 1990s. An overview of the proposed network architecture of the Canadian MSAT network is presented. Management of transponder resources, i.e. power, bandwidth, and spot-beam antennas, which poses a set of unique and significant problems in the design and operation of MSAT networks, is addressed. The three-level hierarchical approach used by the Canadian network is described, and the technical requirements for solving the above problems are identified. The two upper levels employ reconfigurable fixed assignment for allocating transponders to antenna spot beams, and transponder power and bandwidth to different services. The lowest level employs demand assignment and packet multiple access protocols for resource sharing among different subscribers. Uncoupling the resource management problems into manageable portions reduces the complexity and enhances the robustness of the network.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Spanning multiaccess channel hypercube computer interconnection

A distributed computer system based on a hypercube topology is proposed, where multiaccess channels spanning all dimensional axes provide processor interconnection. The multiprocessor system can be built at relatively low cost by combining the recent advances in high-capacity channels available through fiber optics, and demand-assignment multiple-access protocols, creating a highly fault-tolerant system with good average packet delay and average distance characteristics, at a significantly reduced cost. A totally distributed system has been achieved in which the packets are self-routing, able to take advantage of the multiple paths of equal length between two modes. The proposed structure gives a highly fault tolerant system, degrading gracefully in the presence of failures.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A Unified Approach to Local Area Network Interconnection

An approach to local area network interconnection is presented Which combines the advances in static interconnection topologies, demand assignment multiple access protocols, and the availability of high-bandwidth fiber optic channels to create a cost-effective structure capable of interconnecting a large number of LAN's with heavy traffic. This approach is independent of the protocol implemented at each LAN. The structure is based on a hypercube topology where each vertex of the graph represents a LAN. Multiple access channels spanning all dimensional axes are used in this scheme. This approach is compared to a topology with direct point-to-point connections between all nodes sharing a common axis. Through the development of the degree, diameter, average distance, cost, and average packet delay, we show that using fewer high-capacity channels, a LAN interconnection network with excellent performance characteristics can be constructed, able to support a large number of LAN's with heavy traffic at a significant reduction in cost over the point-to-point case. The resulting structure has many of the desirable characteristics for static interconnection networks such as high fault tolerance, totally distributed packet routing in the interconnection network, low average distance for good performance, and low degree, resulting in low cost. For the total number of required LAN nodes and the expected amount of internode traffic, the structure is optimized for minimum cost.

Modeling and Verification of Real-Time Protocols for Broadcast Networks

A class of demand-assigned multiple-access (DAMA) protocols have been proposed for high-speed local area networks (LAN's) that offer integrated services for data, voice, video, and facsimile traffic. These protocols exploit the directionality of signal propagation and implement stringent real-time constraints to achieve collision-freedom. Correct implementation of DAMA protocols will require a very careful analysis of time-dependent interactions using a formal method. To date, most verification methods have been focused on asynchronous communication over point-to-point links.

A Reliable Pipeline Protocol for the Message Service of a Land Mobile Satellite Experiment

This paper describes and analyzes a pipeline protocol for the data message communications of MSAT-X, a proposed experimental satellite-based mobile communications network. A demand-assigned multiple access protocol using pure ALOHA for making reservation requests has been developed for MSAT-X under error-free assumptions. Preliminary propagation studies indicate that the shortterm bit error rate of satellite channels in a mobile environment can be as high as 10-3. Therefore, error-control schemes must be developed to ensure reliable transmissions. In this paper, we propose a retransmission scheme using selective repeat to minimize the end-to-end delay. We also use slotted ALOHA for making reservation requests to increase the overall system throughput. Since the number of channels available for reservation and data channels is essentially fixed for a given voice call blocking probability and a fixed call arrival rate, the analysis presented in this paper is also applicable to the integrated voice and data services of MSAT-X. Various operational scenarios have been investigated.

Performance evaluation of spanning multiaccess channel hypercube interconnection network

The spanning multiaccess channel hypercube (SMCH) is a distributed computer interconnection structure, based on a hypercube topology, where processors are connected using multiaccess channels spanning all dimensional axes. The channel access arbitration is achieved through demand assignment multiple access (DAMA) protocols. We compare the SMCH to the generalised hypercube (GHC), the nearest neighbour mesh hypercube (NNMH), cube connected cycles (CCC), and the Boolean cube (BCube). The comparison shows the SMCH to have excellent performance characteristics, at a cost significantly lower than comparable structures. This is achieved by combining the recent advances in processor interconnection architectures, the economies of scale available with highcapacity channels, and demand assignment multiple-access protocols, to form a highly efficient, cost effective, distributed computer system.

An integrated voice and data multiple-access scheme for a land-mobile satellite system

A Land-Mobile Satellite System (LMSS) is a satellite-based communications network which provides voice and data communications to mobile users in a vast geographical area. By placing a "relay tower" at a height of 22300 mi, an LMSS can provide ubiquitous radio communication to vehicles roaming in remote or thinly populated area. LMSS is capable of supporting a variety of services, such as two-way alphanumeric service, paging service, full-duplex voice service, and half-duplex dispatch service. A Network Management Center (NMC) will handle the channel requests, channel assignments, and in general the network control functions. A pool of channels is managed at the NMC to be shared by all mobile users. An integrated demand-assigned multiple-access protocol has been developed for the experimental LMSS. The pool of channels is divided into reservation channels and information channels. The information channels can be assigned by the NMC to be either voice channels or data channels. Each mobile user must send a request through one of the reservation channels to the NMC via the ALOHA random-access scheme. Once the request is received and processed, the NMC will examine the current traffic condition and assign an information channel to the user. NMC will periodically update the partitions between the reservation channels, voice channels, and data channels to optimize system performance. Data channel requests are queued at the NMC while voice channel requests are blocked calls cleared. Various operational scenarios have been investigated. Tradeoffs between the data and voice users for a given delay requirement and a given voice call blocking probability have been studied. In addition, performance impacts of such technological advancements as satellite on-board switching and variable bandwidth assignment are discussed.