A hybrid mac protocol for multimedia traffic in wireless networks

International Journal of Computer …, 2011

This article presents a survey on medium access control protocols for wireless multimedia networks. A basic overview of MAC protocol concepts is presented, and a framework is developed for comparisons. The MAC protocols covered in this article include Random Access protocols, Contention less protocols, TDMA CDMA, third-generation WCDMA schemes and Hybrid protocols proposed for wireless Multimedia Networks. The operation of each protocol is explained, and its advantages and disadvantages are presented. Finally, a qualitative comparative outline of the discussed protocols is provided.

Lecture Notes in Computer Science, 2004

In CDMA-based packet data systems such as HDR and HS-DPA which are designed to support high rate services, BSs transmit data packets with a maximum power based on time multiplexing mode such that only one user can be serviced at a time. In this paper, we propose a power-allocation-combined scheduling algorithm for HDR-like systems in which we adopt a code division multiplexing (CDM) transmission method in the downlink common channel in order to utilize channel orthogonality such that we can serve more than one user at a time slot specially when there exist remaining resources after serving the firstly selected user by the scheduler. Simulation results show that the proposed scheme outperforms the conventional scheme as the traffic load increases. 1 Introduction CDMA-based high-rate packet data systems, called as the 3.5 th generation CDMA systems beyond IMT-2000, such as HDR and HSDPA adopt common shared channels in the forward link in order to provide a high bit rate packet data service and an improved throughput. For example, HDR systems adopt the forward packet data channel (FPDCH)[1] while HSDPA systems use the high speed downlink shared channel (HS-DSCH)[2]. These common shared channels are capable of supporting high bit rate by employing adaptive modulation and coding with Hybrid ARQ, turbo codes and transmit diversity. One of the most distinct features of these common shared channels however is to adopt rate adaptation and to service multiple packet data users based on time multiplexing mode. In addition, a mix of services with different requirements is expected to be serviced in the context of next generation CDMA systems. In order to support the quality of various services through the common shared channels, efficient MAC protocols are needed. More specially, it is expected that a scheduling algorithm among MAC protocols plays an important role in the common shared channels since it controls the allocation of the shared resources among users and to a large extent determines the overall behavior of the system. Recently, many works have been done regarding scheduling algorithm for common shared channels in order to increase total throughput and guarantee

2001

Integration of CBR, voice, VBR, data and control traffic over the wireless ATM channel using the proposed AR-TDMA protocol is considered in the paper. The performance of the AR-TDMA in conjunction with the AFPBA-ASA protocol and FPBA-APCC protocol has been investigated and the simulation results are presented showing that the protocol satisfies the required QoS of each traffic category while providing a highly efficient utilisation of approximately 96% for the wireless ATM channel.

IEEE Transactions on Wireless Communications, 2000

Today one of the challenges for wireless network operators is to find techniques which will make it possible to introduce multimedia capabilities into mobile communications. The application of a wireless network structure made up of pico-cells to solve this problem will cause an increase in the handover rate. Therefore, a major requirement in a wireless environment is to design an effective call admission control (CAC) strategy to minimize the handover drop probability. Another important requirement is to maximize network utilization, in terms of the mean number of channels used. The target of the paper is to define a resource management strategy for heterogeneous adaptive-rate traffic. The proposed strategy is actually a combination of two: a CAC management strategy and a bandwidth management one. The CAC management strategy extends the Guard Channel strategy to obtain priority-based CAC management for adaptive-rate sources; the bandwidth management strategy allows channels to be assigned proportionally to the throughput window declared by users. In order to assess the effectiveness of the proposed CAC strategy, two Markov models of the system are introduced: one, from the network point of view, to evaluate global system performance, and another, from the user point of view, to evaluate the performance each user is provided with by the network. Numerical examples conclude the paper to analyze which factors most affect performance when the source rate is adaptive and the proposed admission strategy is applied.

IEEE Journal on Selected Areas in Communications, 2000

This paper presents and analyzes a new near-optimum medium access control (MAC) protocol. The proposed access scheme is suitable for a CDMA mobile communication environment, and keeps under control and upper bounded the number of simultaneous transmissions. It has a delay performance approaching that of an ideal optimum M/M/K system, where K is the number of spreading codes being used (maximum number of simultaneous transmissions). The protocol is a free random access protocol when the traffic load is light, and switches smoothly and automatically to a reservation protocol when traffic load becomes heavier. It is based on distributed queues and a collision resolution algorithm. Moreover, a physical receiver structure is proposed and analyzed in order to preserve the robustness of the protocol in a wireless link. The results obtained show that the protocol outperforms other well known medium access protocols in terms of stability and delay, even when taking into account the loss caused by channel propagation conditions.

ETRI Journal, 2006

2008

In this paper we propose an optimized WLAN MAC protocol for multimedia applications. The proposed MAC protocol consist of 3 main optimizing architectures, traffic segregation, specific service interval (SI) for voice and video traffic and smaller contention window (CW). Traffic segregation segregates real-time traffic from best-effort traffic while specific service interval provides voice and video traffic with the SI based on its mean arrival rate. In the contention time frame, the CW is made smaller to reduce delay and increase throughput. Ns2 is used as a simulating tool to compare the results of our proposed protocol with the legacy 802.11 and the 802.11e protocols. We show that our protocol has significantly better throughput than the legacy 802.11 and the 802.11e. Fluctuations in the throughput is also shown to be lower in our proposed protocol. The technique implemented also provides easier and better management of realtime traffic to support guaranteed quality of service (QoS).

IEEE Communications Letters, 2000

In this letter we evaluate the performance of wideband CDMA cellular systems providing different classes of multimedia traffic and supporting user mobility. A Markovian teletraffic model of the user dynamics is developed. Constraints are imposed in the model which account for the multiple access interference among active users. Results are shown in terms of call blocking probabilities and average number of active connections. The methodology proposed is a useful tool for the design and planning of third generation cellular systems. Index Terms-CDMA mobile systems, Markovian models, multimedia traffic.

2002

Abstract A hybrid access protocol known, as contention time-division multiple access (C-TDMA), is presented and analyzed in a radio cellular multiuser system scenario. C-TDMA shows some features of contention-based (slotted-ALOHA) and reservation-based (packet reservation multiple access, PRMA) protocols. It has been recommended for use in the uplink of future European multimedia distribution systems. A simple Markov model is proposed to describe C-TDMA behavior.

Computer Standards and Interfaces, 2012

An efficient bandwidth allocation scheme in wireless networks should not only guarantee successful data transmission without collisions but also enhance the channel spatial reuse to maximize the system throughput. The design of high-performance wireless Local Area Network (LAN) technologies making use of TDMA/FDD MAC (Time Division Multiple Access/Frequency Division Duplex -Medium Access Control) is a very active area of research and development. Several protocols have been proposed in the literature as TDMA-based bandwidth allocation schemes. However, they do not have a convenient generic parameters or suitable frame repartition for dynamic adjustment. In this work, we undertake the design and performance evaluation of a QoS (Quality of Service)-aware scheme built on top of the underlying signaling and bandwidth allocation mechanisms provided by most wireless LANs standards. The main contribution of this study is the new guarantee-based dynamic adjustment algorithm used in MAC level to provide the required QoS for all traffic types in wireless medium especially Wireless ATM (Asynchronous Transfer Mode). Performance evaluation of this approach consists of improving the bandwidth utilization, supporting different QoS requirements and reducing call reject probability and packet latency.