User bandwidth requirement based OFDMA (Orthogonal Frequency Division Multiple Access) system downlink resource allocation method under imperfect channel state information

Abstract

A user bandwidth requirement based OFDMA (Orthogonal Frequency Division Multiple Access) system downlink resource allocation method under the imperfect channel state information comprises obtaining a user bandwidth requirement based sub-channel allocation strategy, deducing a user bandwidth allocation rate formula and a probability density function of user sub-channel occupation signal noise ratio estimation values according to the user bandwidth requirement based sub-channel allocation strategy and performing deduction according to the probability density function to obtain a user average bit error rate expression; enabling a link spectral efficiency maximization problem under the condition that user bandwidth requirements and average bit error rate upper limit requirements are met to be decomposed into two problems of sub-channel allocation and modulation scheme optimization under the restriction of the average bit error rate; establishing a mathematical model of the sub-channel allocation problem to obtain user weight vectors which meet the user bandwidth requirements; performing feasible search on the optimal modulation scheme to obtain a user optimal modulation scheme vector for the problem of the modulation scheme optimization under the restriction of the average bit error rate. The user bandwidth requirement based OFDMA system downlink resource allocation method under the imperfect channel state information can be applied to an actual OFDMA system downlink.

Description

technical field [0001] The invention belongs to the field of wireless communication, and relates to a resource allocation method in an OFDMA (Orthogonal Frequency Division Multiple Access) system. Background technique [0002] With the development of the long term evolution (Long Term Evolution, LTE) system in which the wireless cellular network is partially put into commercial use from the first generation to the present, people's requirements for the service quality of services provided by the network are also increasing. How to provide users with more high-quality services while maximizing system spectrum efficiency on limited spectrum resources is the main technical challenge that wireless broadband cellular networks will face in the future. OFDMA can realize efficient and flexible resource allocation, and has the advantages of high spectrum efficiency, and is especially suitable for downlink transmission that does not require high peak-to-average power ratio. [0003] ...

AI Technical Summary

Problems solved by technology

In an actual system, resource allocation under the assumption that CSI is ideal (accurate) will lead to a decrease in system performance

[0004] At present, most resource allocation algorithms based on non-ideal channel state information generally only consider the impact of channel estimation errors on system performance, or only consider the impact of CSI delay on system performance

Literature Awad M K, Mahinthan V, Mehrjoo M, et al. A Dual-Decomposition-Based Resource Allocation for OFDMA Networks With Imperfect CSI[J]. IEEE Transactions on Vehicular Technology, 2010, 59(5): 2394-2403. and Zarakovitis C C, Ni Q, Skordoulis D E, et al. Power-Efficient Cross-Layer Design for OFDMA Systems with Heterogeneous QoS, Imperfect CSI and Outage Considerations[J]. IEEE Transactions on Vehicular Technology, 2012, 61(2): 781-798 .The error caused by the two factors of channel estimation and CSI delay is modeled as a complex Gaussian random variable with 0 mean value, and its variance is used to describe the accuracy of ICSI. This ICSI modeling method cannot reflect different CSI delays and Influence of Different Doppler Frequency Shift on ICSI Accuracy

Therefore, applying the above research results to the actual OFDMA system downlink will lead to a decrease in system performance

Literature Kuhne A, Klein A. Throughput Analysis of Multi-User OFDMA-Systems Using Imperfect CQI Feedback and Diversity Techniques [J]. IEEE Journal on Selected Areas in Communications, 2008, 26(8): 1440-1450. Analyzed channel estimation Error, CSI delay, CSI quantization bit number and feedback channel bit error rate affect the OFDMA-FDD system throughput, but it adopts the maximum signal-to-noise ratio scheduling strategy, which does not take into account the different bandwidth requirements of users. Therefore, in the non-ideal Under the condition of channel state information, it is of great practical significance to study the resource allocation method that maximizes the downlink spectrum efficiency of OFDMA systems under the constraints of satisfying user bandwidth requirements and average bit error rate.

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