With the rapid development of wireless communication technology and the rapid increase in demand for network bandwidth, IEEE 802.16e is an emerging network technique that has been deployed in many metropolises. In add...
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With the rapid development of wireless communication technology and the rapid increase in demand for network bandwidth, IEEE 802.16e is an emerging network technique that has been deployed in many metropolises. In addition to the features of high data rate and large coverage, it also enables scalable video multicasting, which is a potentially promising application, over an IEEE 802.16e network. How to optimally assign the modulation and coding scheme (MCS) of the scalable video stream for the mobile subscriber stations to improve spectral efficiency and maximize utility is a crucial task. We formulate this MCS assignment problem as an optimization problem, called the total utility maximization problem (TUMP). This article transforms the TUMP into a precedence constraint knapsack problem, which is a NP-complete problem. Then, a branch and bound method, which is based on two dominance rules and a lower bound, is presented to solve the TUMP. The simulation results show that the proposed branch and bound method can find the optimal solution efficiently.
WiMAX-the Worldwide Interoperability for Microwave Access is a promising technology for offering high-speed data, video and multimedia services over mobile platform evolving toward all IP networks. The increasing dema...
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WiMAX-the Worldwide Interoperability for Microwave Access is a promising technology for offering high-speed data, video and multimedia services over mobile platform evolving toward all IP networks. The increasing demand of WiMAX for VoIP and high-speed multimedia is due to the simplicity of installation and cost reduction compared with the traditional wired DSL cable. The challenges to service providers lie with the Quality of Service (QoS) under varying fading environment while at the same time maximizing for resource utilization. In this paper, a rigorous and comprehensive performance study of mobile WiMAX has been made with respect to adaptive modulation and coding techniques considering the variation in the speed of the mobile, path-loss, scheduling services and application type for comparing with the fixed type of modulations. The OPNET 14.5. A modeler for WiMAX platform has been used as simulator for adaptation at the physical layer of the transmission in WiMAX OFDMA structure. Observation reveals that dynamic adaptation of modulation and coding schemes based on channel condition enables better QoS while consuming low overall bandwidth of the system. Copyright (C) 2011 John Wiley & Sons, Ltd.
In accordance with the channel status information, modulation and coding method can be changed adaptively to enhance the throughput in Long Term Evolution Time Division Duplexing (LTE TDD) system. With the scheme of E...
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ISBN:
(纸本)9781424438181
In accordance with the channel status information, modulation and coding method can be changed adaptively to enhance the throughput in Long Term Evolution Time Division Duplexing (LTE TDD) system. With the scheme of Exponential Effective SNR Mapping (EESM) and Mutual Information Effective SNR Mapping (MIESM), two adaptive modulation and coding mechanisms are proposed in this paper. Simulation results show that the performance on network throughput can be improved effectively both in the ideal channel and multi-path channel environment.
Multi-carrier modulation techniques, such as OFDM, are attractive propositions for the design of future broadband wireless communication systems due to higher spectral efficiency than CDMA. A capacity enhancing techni...
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ISBN:
(纸本)0780388879
Multi-carrier modulation techniques, such as OFDM, are attractive propositions for the design of future broadband wireless communication systems due to higher spectral efficiency than CDMA. A capacity enhancing technique to be commonly used in these systems is adaptivemodulation/coding (AMC) for link adaptation. With AMC, the modulation and coding Scheme (MCS) is selected based on the channel quality information. MCS selection is an imperfect process by nature, due to, for example, the variability of the channel. Moreover, since the set of available MCSs is quantized, it is not always possible to select the optimal rate. Using these non-optimal MCS values will result in reduced system capacity. This paper describes a method that attempts to maximize system and user throughputs in a multi-carrier system by overcoming the impacts of such non-optimal MCS selection through the use of hybrid ARQ (HARQ). This method relies on aggressive MCS selection and multiple HARQ transmissions. The performance impact of this method on various types of packet data applications is evaluated by system level simulation. Simulation results indicate that significant system and user throughput gains can be achieved by this method.
adaptive modulation and coding (AMC) is a powerful technique for improving the spectral efficiency or the error performance in wireless packet networks over fading channels. In this article, using a fixed number of mo...
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ISBN:
(纸本)9781424409549
adaptive modulation and coding (AMC) is a powerful technique for improving the spectral efficiency or the error performance in wireless packet networks over fading channels. In this article, using a fixed number of modulation and coding modes we propose a variable power transmission scheme for transmission of packets over block-fading wireless channels. We obtain the general form of optimal power adaptation and optimum AMC mode switching levels that maximize spectral efficiency under prescribed packet error rate (PER) constraint while satisfying an average transmit power constraint. Numerical results reveal that in wireless packet systems with limited packet length, the proposed scheme provides substantial average spectral efficiency gain when compared to the non-adaptive case. The optimization framework presented in this article would be useful for cross-layer optimization of physical layer in packet networks.
Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems can provide significant space diversity and combat multi-path fading, thus attracting increasing attention for the design o...
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ISBN:
(纸本)9781424405688
Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems can provide significant space diversity and combat multi-path fading, thus attracting increasing attention for the design of future broadband wireless communication systems. One enhancement technique commonly used in such systems is adaptive modulation and coding (AMC) for link adaptation. With AMC, the modulation and coding scheme (MCS) is adaptively selected based on channel quality indication (CQI). In this paper, we give a comprehensive analysis of mapping between signal to interference plus noise ratio (SINR) fed beck by the mobile station and MCS to be used to transmit dada, while taking into account hybrid ARQ (HARQ) operation. Then we apply such mapping criteria to MIMO-OFDM systems and develop a systematic algorithm for MCS selection to maximize the system throughput. The performance of the proposed approach is evaluated by extensive system level simulation. Results indicate that compared to traditional MCS selection schemes significant system throughput gain can be achieved by this method.
The end-to-end Quality of Service (QoS) is getting more and more importance nowadays. QoS is composed of many parameters, like bit error rate (BER) delay, jitter etc. This paper will make the mathematical analysis of ...
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ISBN:
(纸本)9781424416622
The end-to-end Quality of Service (QoS) is getting more and more importance nowadays. QoS is composed of many parameters, like bit error rate (BER) delay, jitter etc. This paper will make the mathematical analysis of the spectral efficiency of adaptive modulation and coding (AMC) which - unlike conventional adaptive modulation and coding - takes into consideration the bit error requirements of different service classes, beside the instantaneous channel conditions. The paper will provide results on average spectral efficiency, mode selection probabilities and average bit error rate performance of proposed and conventional adaptivemodulation (AM) in multiplicative, slow Rayleigh fading channel. The fading is assumed to be slow enough, that the adaptivemodulation can adapt to the variable channel state.
A Markov Based method for modulation and coding Scheme (MCS) selection is proposed for Pilot assistant adaptive modulation and coding scheme (AMC) with Hybrid ARQ (HARQ) retransmissions. A first-order finitestate Mark...
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ISBN:
(纸本)9781424403394
A Markov Based method for modulation and coding Scheme (MCS) selection is proposed for Pilot assistant adaptive modulation and coding scheme (AMC) with Hybrid ARQ (HARQ) retransmissions. A first-order finitestate Markov model (FSMM) is introduced to represent the time correlation character of channel fading during (Channel Quality Indicator) CQI feedback and HARQ retransmissions. According to different QoS target, such as maximize the air interface throughput or maintains a target Frame Error Rate (FER) for each user, The Markov Based method can deduce different reference Pilot thresholds for each MCS. Theoretical analysis and link level simulation results both show the efficiency of the Markov based method for Pilot threshold calculation according to different QoS target and different HARQ retransmission times.
This paper analyzes the performance of a mobile multihop relay (MMR) system which uses intermediate mobile relay stations (RSs) to increase service coverage area and capacity of a communication system. An analytical f...
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This paper analyzes the performance of a mobile multihop relay (MMR) system which uses intermediate mobile relay stations (RSs) to increase service coverage area and capacity of a communication system. An analytical framework for an MMR system is introduced, and a scheme for allocating the optimum radio resources to an MMR system is presented. It is very challenging to develop an analytical framework for an MMR system because more than two wireless links should be considered in analyzing the performance of such a system. Here, the joint effect of a finite queue length and an adaptive modulation and coding (AMC) scheme in both a base station (BS) and an RS are considered. The traffic characteristics from BS to RS are analyzed, and a three-dimensional finite-state Markov chain (FSMC) is built for the RS which considers incoming traffic from the BS as well. The RS packet loss rate and the RS average throughput are also derived. Moreover, maximum throughput is achieved by optimizing the amount of radio resources to be allocated to the wireless link between a BS and an RS.
Based on the IEEE 802.16e standard, WiMAX has proposed a relay-based mechanism, namely IEEE 802.16j, to extend the service area of the Multihop Relay Base Stations (MR-BSs) and to improve the Received Signal Strength ...
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Based on the IEEE 802.16e standard, WiMAX has proposed a relay-based mechanism, namely IEEE 802.16j, to extend the service area of the Multihop Relay Base Stations (MR-BSs) and to improve the Received Signal Strength quality. IEEE 802.16j thus can achieve two significant advantages: extending the WiMAX service area with a low-cost solution and compatible with the existing WiMAX specifications. The Relay Station (RS) can be classified into three types: Fixed RS, Nomadic RS and Mobile RS according to diverse features of mobility and relaying range. A multihop-relay WiMAX network including various types of RSs exhibits a critical routing issue, i.e., how to determine an efficient relay-based routing path between a Mobile Station (MS) and a MR-BS. This paper thus proposes an IEEE 802.16j-conformed relay-based adaptive competitive on-line routing approach that focuses on the Non-Transparent Relay-Station (NT-RS) mode, where the path with the least cost and the highest AMC coding rate will be selected in terms of the link bandwidth, path length and channel conditions. Numerical results indicate that the proposed routing approach significantly outperforms other approaches in Fractional Reward Loss, network utilization and average end-to-end path delay.
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