Isochronous Services Research Articles

Energy and Throughput Analysis of Reservation Protocols of Wi Media MAC

WiMedia standardized a fully distributed high data rate communication using ultra wideband (UWB) for wireless personal area networks (WPANs). WiMedia Medium Access Control (MAC) provides a synchronous data communication service by Prioritized Channel Access (PCA) and isochronous service by Distributed Reservation Protocol (DRP). In this paper we propose three different approaches to analyze the reservation protocols, PCA and DRP,

Real-time bandwidth management middleware for multi-session isochronous streaming service in the IEEE1394-based home network

In order to support a multi-session multimedia streaming service in home networks, many critical problems must be considered. In particular, handling the shortage of network bandwidth is one of the most significant and complicated problems. In this paper, a real-time streaming management middleware named as RTSM middleware is suggested as a solution to the problem regarding the IEEE1394-based home network. In order to handle the shortage of network bandwidth and enhance the bus utilization rate, the proposed middleware combines two methods. First, the bandwidth management function measures the usage rate of network bandwidth and restores the residual bandwidth, which is excessively occupied by a streaming service, to free bandwidth. Second, the isochronous streaming (IS) scheduler manages all streaming services in a network according to a priority-based preemptive scheduling policy. This paper focuses on explaining the necessity of bandwidth management in home networks and describing the prototype architecture of the proposed middleware. Evaluation result will show the potential possibility of the proposed middleware.

Active isochronous resource manager for intense dynamic resource allocation service with IEEE1394

With the increased use of various audio/video style digital consumer appliances in home networks, the concurrent support of multiple multimedia streaming services is also clearly required in a home network. Although the isochronous transaction of IEEE 1394 is the best solution for such streaming services, the current IEEE 1394 standard specifications do not consider the dynamic management of isochronous bandwidth resources or a dynamic allocation service for isochronous resources. Accordingly, this paper presents an architecture for an isochronous resource management service that can support an intense dynamic allocation service in an IEEE 1394-based home network environment. The proposed isochronous resource manager service is also implemented using an IEEE 1394 device driver for RTLinux.

Multiple access control protocol for integrated isochronous and bursty data services

A novel multiple access control (MAC) protocol (CHARISMA) is introduced for integrated wireless voice and data services on the uplink channel in a cellular wireless network. The CHARISMA protocol is motivated by the fact that previous protocols ignore the burst errors of the channel due to fading and shadowing. As such, the physical layer of the proposed system is a variable-rate adaptive channel encoder and modulator and thus the instantaneous offered throughput to the MAC layer is variable depending on the current channel state. Given the channel state information provided by the physical layer, priority is given to those mobile terminals with better channel states. Selection diversity is achieved through gathering a large set of new and queued requests such that requests with good channel states can be identified. The multiple access performance of the proposed MAC protocol is compared with traditional TDMA-based MAC algorithms and the RMAV protocol. Extensive simulation results indicate that significant improvements in terms of throughput, delay, and packet loss probability are achieved using the CHARISMA protocol.

A Hybrid Adaptive Wireless Channel Access Protocol for MultimediaPersonal Communication Systems

This paper proposes a new medium access protocol (MAC) protocol for future wireless multimedia personal communication systems, denoted hybrid and adaptive multiple access control (HAMAC) protocol. The HAMAC protocol integrates fixed assignment TDMA protocol, reservation-based protocols, and contention-based protocols into a single wireless network so as to simultaneously and efficiently support various classes of traffic such as constant-bit-rate (CBR), variable-bit-rate (VBR), and available-bit-rate (ABR) traffic. In particular, the HAMAC protocol uses a novel preservation slot technique to overcome the packet contention overhead in packet reservation multiple access (PRMA) like protocols, while keeping most isochronous service features of TDMA protocols to serve voice and CBR traffic streams. A preservation slot is a very short slot which is used to represent a CBR connection when the traffic in the CBR connection is in a silent period in which there is no meaningful data to transmit. Due to the very short length of the preservation slot, it only takes minimal portion of the bandwidth pre-allocated to the CBR connection, so that the remaining bandwidth can be freed for other connections to use. When the CBR source becomes active again, the preservation slot is replaced by normal data slots without any reservation operation, extra delay, or significant bandwidth loss. Consequently, the guaranteed service and simplified signaling features of TDMA protocols, together with the adaptive bandwidth allocation features of PRMA-like protocols, are both realized in the HAMAC protocol. We have analyzed the performance of the HAMAC protocol using extensive simulations. The results show that the HAMAC protocol can achieve very low loss rates for various multimedia traffic with stringent quality of service (QoS) requirements and outperforms state-of-the-art PRMA-like protocols. As a result, the HAMAC protocol appears to be a good candidate for future generation multimedia personal communication systems.

Wavelength division multiplexing-based video-on-demand systems

Serving video-on-demand (VOD) traffic via isochronous transmission service is highly desirable because of the characteristics of VOD traffic. This paper proposes a mechanism to transfer VOD traffic over wavelength division multiplexing (WDM) networks by employing isochronous transmission service. Based on the proposed mechanism, the problem of scheduling isochronous and asynchronous traffic for single-star WDM networks with multiple receivers and transmitters is investigated. The lower bounds on the total switching duration and the number of switching modes for the isochronous and asynchronous traffic scheduling problem are derived. An optimal scheduling algorithm is presented for the cases where only asynchronous traffic exists; and a heuristic algorithm is also proposed for the cases where both the isochronous and asynchronous traffic coexist in the WDM networks. Simulation results indicate that the average switching duration and the average number of switching modes obtained by the proposed algorithm are close to the lower bounds, which implies that the proposed scheduling algorithm is effective.

Evaluation of reservation-arbitrated access schemes for statistical multiplexing of variable-bit-rate video traffic over dual-bus metropolitan area networks

To address the problem of video communications over 802.6 MANs, a reservation-arbitrated (RA) access protocol is proposed which allows a variable-bit-rate video source to reserve isochronous channels on a bandwidth-on-demand basis. The paper explains the general method of RA access, compares four different schemes of acquiring incremental bandwidth in response to a reservation request, and evaluates the performance of RA access by simulations using two video-source models. Results indicate that RA access provides fair service under a cyclic capturing mechanism, permits statistical multiplexing while providing nearly isochronous transport service, allows a video source to adapt to its reserved bandwidth during network congestion, and facilitates the implementation of layered video coding techniques.

Reservation arbitrated access — a bandwidth on demand protocol for multiplexing variable bit rate isochronous traffic over dual bus metropolitan area networks

With the advent of multimedia communication services, transport of real-time traffic over metropolitan area networks (MANs) is becoming an important problem. We present a novel reservation arbitrated (RA) access protocol for multiplexing variable bit rate isochronous (VBRI) traffic such as packet voice and video over dual bus MANs in general and IEEE 802.6 MANs in particular. In combination with a cyclic release mechanism, RA access allows variable bit rate traffic sources (VBRSs) to capture and reserve some isochronous channels on a bandwidth on demand basis in a round robin fashion. For a reasonable bus length suitable for metropolitan coverage, it is possible to select operation parameters which enable contention free access in the reservation process. Bandwidth utilization can be further improved by employing a movable boundary option to efficiently integrate VBRI traffic with other traffic. System performances including packet loss ratio, packet delay, delay jitter, probability distribution of consecutive packet loss and channel utilization are analyzed by both theoretical computations and computer simulations for voice, video conference and motion video traffic. Results indicate that the protocol is fair and provides a nearly isochronous transport service while ensuring efficient bandwidth utilization, yielding substantial capacity improvements over pre-arbitrated (PA) access. Compared to queue-arbitrated (QA) access, RA access not only provides variable bit rate isochronous channels but also allows VBRSs to adapt to the reserved bandwidth during network congestion so that performance degradation can be minimized. RA access complements existing PA and QA access methods in 802.6 MANs to provide a complete traffic transport solution for all types of BISDN services.

On a MAC Protocol Based on Distributed Cycles

This paper introduces a novel transmission scheduling scheme applicable to high-speed ring networks. The essence of the proposed scheme is a special marker, called the terminator, circulating in the ring. The maximum normalised throughput, of our protocol does not degrade with the increasing propagation length of the ring and the stations endure small access delays under light load. Our protocol also offers a full-scale isochronous service without any need for fixed reservations, negotiations, or other preparatory stages.

Connection oriented data service in DQDB

The DQDB standard accepted by the IEEE Standards Board in 1990 is incomplete in the sense that it does not specify details of isochronous service and connection oriented data service. In this paper, we discuss the performance of a protocol which has been studied in all meetings of IEEE 802.6 since 1991. The Guaranteed Bandwidth (GBW) protocol for Connection Oriented Data Service turns out to be a very promising candidate for variable bit rate communication with predictable bandwidth requirements.

Provision of isochronous service on IEEE 802.6

The author concentrate on the provision of isochronous services to users via the existing IEEE 802.6 framework using Q.931 as the signalling protocol for providing call control functions. They present possible scenarios of isochronous service provisioning via the IEEE 802.6 network. Real time performance for call setup procedures is simulated and analyzed with different priority schemes for transferring signalling messages. The results show that using a prioritized queue arbitrated (QA) bandwidth to send signalling messages greatly reduces call setup delay. Call setup delays are determined using both Poisson-type and bursty type data traffic models. The positioning of the bandwidth manager, the virtual channel identifier (VCI) server and the Q.931 signalling termination is shown to influence call setup performance. >

A distributed paths migration scheme for IEEE 802.6 based personal communication networks

Wireless personal communications will be provided via the usage of microcells in urban areas. The current centralized architecture may be unsuitable with the increased processing load and handoff rate associated with microcells. Some distributed architectures based upon interconnected IEEE 802.6 MAN'S for wireless personal communications have been proposed recently. The IEEE 802.6 MAN is attractive since it also provides isochronous services which are quite suitable for voice communications. In such a network, a communication path between two mobile terminals may be inefficient due to the lack of better paths when the path is established or become inefficient due to the mobility of terminals, e.g., the path elongates and consumes too much isochronous channels. In this paper, a distributed paths migration scheme is proposed for the IEEE 802.6 based personal communication networks. This distributed scheme automatically recognizes inefficient paths and migrates them to better ones, if any. During the migration, the property of isochronous services is also preserved. The performance of this scheme is evaluated by simulations. Simulation results show that the proposed paths migration scheme dramatically reduces the number of isochronous channels consumed per path. As a result, the call blocking rate is reduced and the number of successful established paths is increased significantly. >

FDDI: current issues and future plans

Fiber Distributed Data Interface (FDDI), a set of standards developed by the American National Standards Institute (ANSI) X3T9.5 Task Group, is reviewed. The timed token access method, used to share the medium among stations in this 100-Mbit/s local area network (LAN), differs from the traditional token access method in that the time for the token to walk around the ring is accurately measured by each station and used to determine the usability of the token. FDDI-II, which provides support for isochronous service in addition to the asynchronous and synchronous service provided by FDDI, the media-dependent physical layer (PMD) standard called low-cost fiber PMD (LCF-PMD), and the implementation of FDDI on the synchronous optical network (SONET) are discussed.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

An emulator for evaluating DQDB performance

This paper presents the design and implementation of a DQDB network emulator, developed at Lancaster University. The emulator uses standard Unix processes and System V named pipes to create a model of a Distributed Queue Dual Bus subnetwork of a Metropolitan Area Network. Apart from gaining insights into the DQDB protocol implementation based on a finite state machine model, the goals of the work reported in this paper included the performance evaluation of DQDB networks and the provisioning of a suitable platform to investigate various isochronous service management issues. The paper provides results on the operations of the distributed queue state machines and on the performance evaluation of DQDB networks. Finally, future developments of the emulator are identified.

ATM technology: a backbone for high speed computer networking

The use of data communication equipment in local environments is increasing rapidly. Applications such as electronic mail, file transfer, CAD/CAM, etc., currently result in the installation of more and more LANS in offices. Since the industry becomes more and more located at different places worldwide, the interconnection of these LANs becomes more and more a requirement. With the increasing number of applications, higher and higher bit rates are required at those interconnections. Different solutions exist to connect these LANs. Most of them are based on B-ISDN tecniques, using the ATM (Asynchronous Transfer Mode) cell relay principle. The first solution, which is initially applicable in a metropolitan area is based on the MAN (Metropolitan Area Network) technology as standardized by IEEE 802.6. It is based on the DQDB (Distributed Queue Dual Bus) principle, and offers to the customer both high speed data interconnectivity and isochronous services. To cover larger areas than metropolitan ones, MANs can be connected by high speed leased lines, or by an ATM backbone network. An alternative solution, but with some complementarity to MANs, is called an ATM crossconnect network. This solution offers to the customers semi-permanent high speed connectivity. This solution can also be used as an enhancement to MANs, to provide a backbone to connect multiple MANs. Such an ATM crossconnect network can be enhanced with a connectionless server, to offer to the customers full international high speed data connectivity. Both solutions use the ATM transfer mode of B-ISDN and thus allow a gradual evolution to the full B-ISDN, in which each service can demand dynamically its virtual connection (or multiple virtual circuits for multimedia services). To ensure a worldwide connectivity, all involved telecommunication operators have to plan the necessary coordination.

FFOL and its relationship to the MAN/WAN environment

The FDDI Follow-On LAN (FFOL) standard is being developed as a successor to FDDI. Thus FFOL, like FDDI, must address FDDI-II Wideband Channel isochronous services in the emerging voice/video multimedia market. In addition, cost effective integration of FFOL with broadband services in the emerging MAN/WAN market is essential. This means cost-effective interfacing to both SONET/SDH transmission media and cell-based (ATM) Broadband-ISDN services. This paper addresses these issues, and makes the case for FFOL as the next generation gigabit-per-second LAN.

Distributed Bandwidth Management in FDDI Networks with Multiple Isochronous Services

The Fiber Distributed Data Interface (FDDI) is a proposed American National Standard for a 100 Mbps token ring using an optical fiber medium. The timed token protocol used in FDDI allows the integration of digital voice, video, interactive data communications and large file transfers over the same network. The performance of the protocol has been studied in the past for asynchronous class of service with a single isochronous service.In this paper, we focus on the performance of the protocol when multiple class of isochronous services are to be provided along with the asynchronous class of service. It is found that the performance of the protocol is affected by the different delay requirements of different isochronous services. The performance of the protocol is studied through simulation with two classes of isochronous services viz video and voice. We also propose two distributed algorithms to improve the performance of the protocol under multiple isochronous services.

Guaranteed bandwidth transport service in multihop networks

This paper deals with the feasibility of a Guaranteed Bandwidth Transport Service (GBTS), usually employed for the handling of isochronous and/or data services with real time requirements, on Multihop Networks (MHNs). A Resource Allocation Protocol (RAP) for the set-up of GB calls is proposed. This protocol allows the low cost requirements of a LAN/MAN node to be satisfied, together with a high flexibility in bandwidth allocation. In the paper a performance study is carried out to verify the response of the MHNs to GB traffic. In particular, the path blocking probability has been evaluated by means of an analytical model in the cases of balanced and unbalanced loads. Moreover, a comparison with the performance of similar LAN/MAN structures, i.e. simple ring and ring with spatial reuse is carried out. Finally, a methodology to manage the resources in order to make the grade of service independent of the physical location of the network nodes is proposed and its impact on the network performance is evaluated.

Overview of FFOL — FDDI Follow-On LAN

FDDI has gained wide acceptance as the follow-on LAN for Ethernet (IEEE 802.3) and Token Ring (IEEE 802.5) LANs as higher performance is required. FDDI, including FDDI-II isochronous services, will be widely deployed in the 1990s as both a backbone and desktop distribution LAN. But what will follow FDDI? Task Group X3T9.5 of ANSI's Accredited Standards Committee (ASC) X3, the standards committee that developed and standardized FDDI, has initiated work on an FDDI Follow-On LAN project, called FFOL, to capitalize on the high degree of consensus that exists today for FDDI. FFOL will include both FDDI and FDDI-II services and will address the key issues for next generation networking and communications systems: interfacing to the SONET/Synchronous Digital Hierarchy, as well as ATM/BISDN services. This paper serves as an introduction to FFOL, focusing on FFOL requirements, project organization, and the architecture of the FFOL. Future papers in this continuing series will address specific components of the FFOL standard.

Architectures for bisdn networks: A performance study

We explore the use of the two current architectures for broadband integrated services digital networks (BISDN) as being defined in IEEE P802.6 (local and metropolitan area network)1 and ANSI-accredited Committee T1's T1S1.5 baseline document.2 The standard currently defines procedures for the median access control (MAC) layer and interfaces for some upper layer services. We, therefore, use the two services defined by the adaptation layer, namely messaging and streaming, to compare their relative performance. It is shown that many conditions are necessary for streaming to out-perform messaging. We then simulate the performance behaviour of these signalling protocols required for the isochronous services of IEEE P802.6 to determine end-to-end delay. This allows us to extend such predictions to the use of IEEE P802.6 as a backbone for concatenated LANs.