Paper Info
Title
Impact of feedback delays on EESM-based wideband link adaptation: Modeling and analysis
Abstract
In orthogonal frequency division multiplexing (OFDM) systems, such as long term evolution (LTE) and WiMAX, a codeword is transmitted over a group of subcarriers. Since the subcarriers see different channel gains in a frequency-selective channel, the modulation and coding scheme (MCS) of the codeword must be selected based on the vector of signal-to-noise-ratios (SNRs) of these subcarriers. Exponential effective SNR mapping (EESM) simplifies this problem by mapping the vector of SNRs into a single, equivalent flat-fading SNR. We develop a new analytical framework to characterize the throughput of EESM-based rate adaptation in such wideband channels in the presence of feedback delays, which make the choice of the MCS partially outdated by the time data transmission takes place. To this end, we first propose a novel bivariate gamma distribution to model the joint statistics of EESM at the times of estimation and data transmission. We then derive a novel expression for the throughput as a function of feedback delay. Our framework works for both correlated and independent subcarriers and for various multiple antenna diversity modes, and is accurate over a wide range of delays.
Year
DOI
Venue
2014
10.1109/GLOCOM.2014.7037425
Global Communications Conference
Keywords
Field
DocType
Long Term Evolution,OFDM modulation,WiMax,broadband networks,codes,feedback,gamma distribution,wireless channels,EESM-based wideband link adaptation,LTE,MCS,OFDM system,WiMAX,bivariate gamma distribution,channel gain,codeword,data transmission,exponential effective SNR mapping,feedback delay,frequency-selective channel,joint statistics,long term evolution,modulation and coding scheme,multiple antenna diversity mode,orthogonal frequency division multiplexing,signal-to-noise-ratio,subcarrier group,wideband channel
Link adaptation,Wideband,Data transmission,Computer science,Computer network,Communication channel,WiMAX,Modulation,Throughput,Orthogonal frequency-division multiplexing
Conference
ISSN
Citations 
PageRank 
2334-0983
4
0.43
References 
Authors
13
2
Name
Order
Citations
PageRank
Jobin Francis1253.58
Neelesh B. Mehta297982.27