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Rate Requirements (rate + requirement)
Selected AbstractsResource allocation algorithms for minimum rates scheduling in MIMO-OFDM systems,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 5 2010Johannes Georg Klotz In this paper, we consider a multiple-input-multiple-output-orthogonal frequency division multiplexing (MIMO-OFDM) downlink scenario, where each receiving mobile station has quality of service requirements, namely minimum rate requirements. For this problem we propose three heuristic resource allocation algorithms, which have a much lower complexity than the existing optimal solution (opt). We compare and evaluate these algorithms according to sum rate performance and complexity. The first strategy is based on a heuristic sum rate maximisation algorithm using the so-called eigenvalue updates. In our second algorithm, we make use of the duality of uplink and downlink, which allows us to do the allocation in the dual uplink. Finally, our third algorithm is based on the well-known zero-forcing dirty paper coding (ZF-DPC) principles, which use the Gram--Schmidt process to orthogonalise the transmissions towards the different users. Copyright © 2010 John Wiley & Sons, Ltd. [source] Adaptive resource allocation in OFDMA systems with fairness and QoS constraints,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2007Liang Chen This paper describes several practical and efficient adaptive subchannel, power and bit allocation algorithms for orthogonal frequency-division multiple-access (OFDMA) systems. Assuming perfect knowledge of channel state information (CSI) at the transmitter, we look at the problem of minimising the total power consumption while maintaining individual rate requirements and QoS constraints. An average signal-to-noise ratio (SNR) approximation is used to determine the allocation while substantially reducing the computational complexity. The proposed algorithms guarantee improvement through each iteration and converge quickly to stable suboptimal solutions. Numerical results and complexity analysis show that the proposed algorithms offer beneficial cost versus performance trade-offs compared to existing approaches. Copyright © 2007 John Wiley & Sons, Ltd. [source] Resource allocation with minimum rates for OFDM broadcast channels,EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 6 2007Carolin Huppert Downlink transmissions with minimum rate requirements over orthogonal frequency division multiplexing (OFDM) channels are commonly done by means of scheduling algorithms. However, regarding it from an information theoretical point of view, this is not optimal since broadcast techniques can achieve higher rates. The drawbacks of the optimum broadcast algorithm are that the signalling overhead is larger than for scheduling and also the computational complexity is much higher. In this paper we propose an algorithm which overcomes these points. This algorithm is a hybrid algorithm combining scheduling and broadcast approaches. Thus, it combines advantages of both methods. Furthermore, we present modifications to this algorithm to avoid irresolvable decoding dependencies. We show by means of simulation results that the proposed algorithm operates close to the optimum performance and that it outperforms a pure scheduling approach. Copyright © 2007 John Wiley & Sons, Ltd. [source] Joint power, subcarrier and subframe allocation in Multihop relay networksINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 7 2009Tolga Girici Abstract In this paper we study the problem of subframe, subchannel and power allocation in OFDMA-based multihop relay networks. The system consists of a base station (BS), a number of relay stations (RS) and mobile stations (MS). We consider frame by frame scheduling, where the frame is divided into two subframes such as BS-RS and RS-MS subframes. We study two different problems, satisfying link rate requirements with minimum-weighted total power and maximizing proportional fairness. For the first problem, we find the optimal solution and also propose a less complex subframe and bandwidth allocation scheme with good performance. For the second problem, we propose an algorithm that outperforms an existing scheme with less feedback. Copyright © 2009 John Wiley & Sons, Ltd. [source] Efficient scheduling discipline for Hierarchical Diff-EDFINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 3 2008Moutaz Saleh Packet networks are currently enabling the integration of traffic with a wide range of characteristics that extend from video traffic with stringent quality of service (QoS) requirements to the best-effort traffic requiring no guarantees. QoS guarantees can be provided in conventional packet networks by the use of proper packet-scheduling algorithms. As a computer revolution, many scheduling algorithms have been proposed to provide different schemes of QoS guarantees, with Earliest Deadline First (EDF) as the most popular one. With EDF scheduling, all flows receive the same miss rate regardless of their traffic characteristics and deadlines. This makes the standard EDF algorithm unsuitable for situations in which the different flows have different miss rate requirements since in order to meet all miss rate requirements it is necessary to limit admissions so as to satisfy the flow with the most stringent miss rate requirements. In this paper, we propose a new priority assignment scheduling algorithm, Hierarchal Diff-EDF (Differentiate Earliest Deadline First), which can meet the real-time needs of these applications while continuing to provide best-effort service to non-real time traffic. The Hierarchal Diff-EDF features a feedback control mechanism that detects overload conditions and modifies packet priority assignments accordingly. Copyright © 2007 John Wiley & Sons, Ltd. [source] Adaptive coding and modulation for satellite broadband networks: From theory to practiceINTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 2 2010Hermann Bischl Abstract This paper presents the detailed design and the key system performance results of a comprehensive laboratory demonstrator for a broadband Ka-band multi-beam satellite system exploiting the new DVB-S2 standard with adaptive coding and modulation (ACM). This complete demonstrator allows in-depth verification and optimization of the ACM techniques applied to large satellite broadband networks, as well as complementing and confirming the more theoretical or simulation-based findings published so far. It is demonstrated that few ACM configurations (in terms of modulation and coding) are able to efficiently cope with a typical Ka-band multi-beam satellite system with negligible capacity loss. It is also demonstrated that the exploitation of ACM thresholds with hysteresis represents the most reliable way to adapt the physical layer configuration to the spatial and time variability of the channel conditions while avoiding too many physical layer configuration changes. Simple ACM adaptation techniques, readily implementable over large-scale networks, are shown to perform very well, fulfilling the target packet-error rate requirements even in the presence of deep fading conditions. The impact of carrier phase noise and satellite nonlinearity has also been measured. Copyright © 2009 John Wiley & Sons, Ltd. [source] | ||||||||||