WATMnet: a prototype wireless ATM system for multimedia personal communication

C&C Res. Labs., NEC Res. Inst., Princeton, NJ
IEEE Journal on Selected Areas in Communications (Impact Factor: 3.45). 02/1997; 15(1):83 - 95. DOI: 10.1109/49.553680
Source: IEEE Xplore


A prototype microcellular wireless asynchronous transfer mode
network (WATMnet) capable of providing integrated multimedia
communication services to mobile terminals is described in this paper.
The experimental system's hardware consists of laptop computers (NEC
Versa-M) with WATMnet interface cards, multiple VME/i960 processor-based
WATMnet base stations, and a mobility-enhanced local-area ATM switch.
The prototype wireless network interface cards operate at peak bit-rates
up to 8 Mb/s, using low-power 2.4 GHz industrial, scientific, and
medical (ISM)-band modems. Wireless network protocols at the portable
terminal and base station interfaces support available bit rate (ABR),
variable bit rate (VBR), and constant bit rate (CBR) transport services
compatible with ATM using a dynamic time-division
multiple-access/time-division duplex (TDMA/TDD) MAC protocol for channel
sharing and data link control (DLC) protocol for error recovery. A
custom wireless control protocol is also implemented between the
portable and base units for support of radio link related functions such
as user registration and handoff. All network entities including the
portable, base and switch use a mobility-enhanced version of ATM
(“Q.2931+”) signaling for switched virtual circuit (SVC)
connection control functions, including handoff. In the first stage of
the prototype, the application-level API is TCP/UP over ATM ABR service
class using AAL5. Early experiments with the WATMnet prototype have been
conducted to validate major protocol and software aspects, including
DLC, wireless control, and mobility signaling for handoff, Selected
network-based multimedia/video applications requiring moderate bit-rates
(~0.5-1 Mb/s) in the ABR mode have been successfully demonstrated on the
laptop PC

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    • "Specifically, if the assigned transmission periods remain constant for the whole duration of the communication, then VBR traffic cannot be efficiently supported. Representative reservation centralized WLAN MAC protocols are the following: distributed-queuing request update multiple access [15], mobile access scheme based on contention and reservation for ATM [16], dynamic slot assignment [17], dynamic time division multiple access [18], and packet reservation multiple access [19]–[21]. Variants of these protocols have also been proposed in literature. "
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    ABSTRACT: In today's wireless networks, there is a great need for quality of service (QoS), because of the time-bounded voice, audio, and video traffic. A new QoS enhanced standard is being standardized by the IEEE 802.11e workgroup. It uses a contention free access mechanism called hybrid control channel access (HCCA) to guarantee QoS. However, HCCA is not efficient for all types of time-bounded traffic. This paper proposes an alternative protocol which could be adapted in hybrid coordination function (HCF). The priority-oriented adaptive control with QoS guarantee (POAC-QG) is a complete centralized channel access mechanism, it is able to guarantee QoS for all types of multimedia network applications, it enhances the parameterized traffic with priorities, and it supports time division access using slots. Furthermore, it instantly negotiates the quality levels of the traffic streams (TSs) according to their priorities, supporting multiple streams to the best quality it can achieve. POAC-QG, compared to HCCA, provides higher channel utilization, adapts better to the characteristics of the different traffic types, differentiates the TSs more efficiently using priorities, and, generally, exhibits superior performance.
    Full-text · Article · Aug 2007 · IEEE Transactions on Vehicular Technology
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    • "In this section we present the design of a DLC protocol which is designed for transporting CBR traffic across the radio links in NEC's WATMnet [5] [13] wireless ATM network. "
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    ABSTRACT: This paper presents a QoS oriented Data Link Control (DLC) framework for transporting Constant Bit Rate (CBR) traffic over wireless ATM links. Data link control is usually omitted in fixed ATM networks because cell corruption due to channel error is extremely rare for reliable media like copper wire and optical fiber. However, for wireless, higher bit error rates are quite common due to shadowing and other fading effects. The purpose of DLC in wireless is to provide error-free transport to the higher layers by recovering corrupted cells at the link layer. A selective reject (SREJ) automatic repeat request (ARQ) based DLC protocol is used for CBR error recovery. For an ARQ based scheme, higher recovery rates can be achieved with larger cell transfer delay, caused by cell retransmissions. Since cell transfer delay and DLC recovery rate both translate to user-perceivable Quality-of-Service (QoS), it is important for the DLC to strike a balance between these two, depending on the application's requirements. To achieve this in our protocol, the retransmission procedure for a CBR cell is constrained to complete within a recovery time interval which is specified by the application at call-setup time. Also, a novel jitter removal scheme that reduces the cell delay variation caused by cell loss and retransmissions, is incorporated as a part of the DLC protocol. The proposed protocol is implemented on NEC's WATMnet prototype system. The implementation and its experimental results are reported for illustrating the performance and feasibility of the presented CBR DLC protocol. The experimental results show that the DLC protocol can be successfully applied for QoS-constrained error recovery of CBR traffic on a per-connection basis. These also indicate that the DLC can be programmed to attain a desirable tradeoff between cell transfer delay and cell recovery rate.
    Preview · Article · Sep 2001 · Wireless Networks
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    • "The authors are with the Department of Electrical and Electronic Engineering The University of Hong Kong, Pokfulam Road, Hong Kong. Publisher Item Identifier S 0018-9545(01)03961-5. [15]. CBR traffic such as voice telephony, VBR traffic such as video conferencing, and ABR traffic such as file data have very different service requirements in terms of delay and loss tolerance and throughput. "
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    ABSTRACT: The multiple access control (MAC) problem in a wireless network has intrigued researchers for years. For a broad-band wireless network such as wireless ATM, an effective MAC protocol is very much desired because efficient allocation of channel bandwidth is imperative in accommodating a large user population with satisfactory quality of service. Indeed, MAC protocols for a wireless ATM network in which user traffic requirements are highly heterogeneous (classified into CBR, VBR, and ABR), are even more intricate to design. Considerable research efforts expended in tackling the problem have resulted in a myriad of MAC protocols. While each protocol is individually shown to be effective by the respective designers, it is unclear how time different protocols compare against each other on a unified basis. In this paper, we quantitatively compare seven previously proposed TDMA-based MAC protocols for integrated wireless data and voice services. We first propose a taxonomy of TDMA-based protocols, from which we carefully select seven protocols, namely SCAMA, DTDMA/VR, DTDMA/PR, DQRUMA, DPRMMA, DSA++, and PRMA/DA, such that they are devised based on rather orthogonal design philosophies. The objective of our comparison is to highlight the merits and demerits of different protocol designs
    Full-text · Article · Jun 2001 · IEEE Transactions on Vehicular Technology
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