Conference Proceeding
Proportional Fair FrequencyDomain Packet Scheduling for 3GPP LTE Uplink.
Comput. Sci. Dept., UCLA, Los Angeles, CA
Proceedings  IEEE INFOCOM 01/2009; DOI:10.1109/INFCOM.2009.5062197 In proceeding of: INFOCOM 2009. 28th IEEE International Conference on Computer Communications, Joint Conference of the IEEE Computer and Communications Societies, 1925 April 2009, Rio de Janeiro, Brazil Source: DBLP

Conference Proceeding: QoEbased performance evaluation of scheduling algorithms over LTE
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ABSTRACT: The LTE specification provides Quality of Service (QoS) of multimedia services with fast connectivity, high mobility, and security. However, 3GPP specifications have not defined scheduling algorithms to support realtime and nonrealtime application services, this has led to the development of a variety of scheduling algorithms in the recent years. Performance is a key factor for assessing the scheduling algorithms. However, the performance analysis and evaluation for existing scheduling algorithms are limited to QoS parameters (e.g. in terms of throughput, packet loss and delay) and/or fairness metrics. It is not clear how these scheduling algorithms perform in terms of Quality of Experience (QoE) metrics (e.g. MOS score) which are more closely linked with end user experience or user perceived quality. In this paper, we investigate and evaluate the performance of three popular LTE downlink schedulers (proportional fairness (PF), exponential proportional fairness (EXPPF), and modified largest weight delay first (MLWDF)) in terms of QoE metric (i.e. MOS score) in addition to normal QoS metrics (e.g. packet loss and delay) for VoIP applications. Simulation results (based on LTESim) show that the best suitable downlink scheduling algorithm is MLWDF, which has short endto end delay (less than 50ms) and allowing maximum number of user access (more than 50 users) at acceptable MOS score (MOS over 3.5). The widely used scheduling algorithm (PF) will increase its endtoend delay over 200ms, when number of user access is over 30. This will limit its application for VoIP when user access number increases. This work would help to assist the design and development of QoEdriven scheduling algorithms for mobile multimedia applications in the future.Globecom Workshops (GC Wkshps), Anaheim, CA; 12/2012 
Conference Proceeding: Uplink Resource Allocation for Frequency Selective Channels and Fractional Power Control in LTE
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ABSTRACT: We consider the allocation of spectral and power resources every subframe (1 ms) on the uplink of the Long Term Evolution (LTE) wideband orthogonal frequency division multiple access (OFDMA) cellular network. System bandwidth is divided into multiple subbands. The fractional power control to manage interference is allowed to be subband dependent. Moreover, the channel gains from the basestation to the mobiles (user equipment (UE) in LTE) can vary with the subband. The power and spectral resources are to be allocated among different UEs in a cell based on channel conditions, desired fairness/QoS, and constraints on power due to interference and power limitation at a UE. For N UEs and M subbands, we exploit the structure of the underlying optimization problem to obtain an interior point method for optimal resource allocation where each Newton step has complexity O(NM). To implement this in an OFDMA system, we delineate a simple control signalling structure where the UE computes in O(M) time a waterfllling solution every subframe it is assigned resources. When the allocation is restricted to contiguous allocation in frequency due to single carrier constraint in LTE, we convert the solution computed above into a feasible solution in O(NM) time. For typical network scenarios, the solution thus computed is numerically shown to be very close to the optimal solution without the contiguous constraint.Communications (ICC), 2011 IEEE International Conference on; 07/2011 
Article: Canonical Dual Method for Resource Allocation and Adaptive Modulation in Uplink SCFDMA Systems
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ABSTRACT: In this paper, we study resource allocation and adaptive modulation in SCFDMA which is adopted as the multiple access scheme for the uplink in the 3GPPLTE standard. A sumutility maximization (SUmax), and a joint adaptive modulation and sumcost minimization (JAMSCmin) problems are considered. Unlike OFDMA, in addition to the restriction of allocating a subchannel to one user at most, the multiple subchannels allocated to a user in SCFDMA should be consecutive as well. This renders the resource allocation problem prohibitively difficult and the standard optimization tools (e.g., Lagrange dual approach widely used for OFDMA, etc.) can not help towards its optimal solution. We propose a novel optimization framework for the solution of these problems that is inspired from the recently developed canonical duality theory. We first formulate the optimization problems as binaryinteger programming problems and then transform these binaryinteger programming problems into continuous space canonical dual problems that are concave maximization problems. Based on the solution of the continuous space dual problems, we derive resource allocation (joint with adaptive modulation for JAMSCmin) algorithms for both the problems which have polynomial complexities. We provide conditions under which the proposed algorithms are optimal. We also propose an adaptive modulation scheme for SUmax problem. We compare the proposed algorithms with the existing algorithms in the literature to assess their performance.Wireless Personal Communications 03/2011; · 0.43 Impact Factor
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