scholarly journals Reducing CQI Signalling Overhead in HSPA

2008 ◽  
Vol 2008 ◽  
pp. 1-5 ◽  
Author(s):  
Saied M. Abd El-atty ◽  
Dimitrios N. Skoutas ◽  
Angelos N. Rouskas
Keyword(s):  
High Speed ◽  
Adaptive Modulation ◽  
Prediction Method ◽  
Wireless Channel ◽  
Traffic Load ◽  
Adaptive Modulation And Coding ◽  
Reporting Scheme ◽  
Channel Quality ◽  
Finite State ◽  
Adaptation Procedure

The efficiency of adaptive modulation and coding (AMC) procedure in high speed Downlink packet access (HSDPA) depends on the frequency of the channel quality information (CQI) reports transmitted by the UE to Node B. The more frequent the reports are the more accurate the link adaptation procedure is. On the other hand, the frequent CQI reports increase uplink interference, reducing thus the signal reception quality at the uplink. In this study, we propose an improved CQI reporting scheme which aims to reduce the required CQI signaling by exploiting a CQI prediction method based on a finite-state Markov chain (FSMC) model of the wireless channel. The simulation results show that under a high downlink traffic load, the proposed scheme has a near-to-optimum performance while produces less interference compared to the respective periodic CQI scheme.

Channel Quality Approximation Based on Shadow Fading Model in GEO Mobile Satellite System

2013 ◽  
Vol 791-793 ◽  
pp. 1941-1944
Author(s):  
Ya Dan Zheng ◽  
Ming Ke Dong ◽  
Jian Jun Wu
Keyword(s):  
Large Scale ◽  
Adaptive Modulation ◽  
Original Data ◽  
Satellite System ◽  
Adaptive Modulation And Coding ◽  
Small Scale ◽  
Shadow Fading ◽  
Channel Quality ◽  
The Difference ◽  
Mobile Satellite

CQI(Channel Quality Indicator) is an essential indicator for AMC(Adaptive Modulation and Coding) technique in LTE. Due to the long delay of GEO satellite channel, CQI prediction is necessary to ensure effective AMC. This paper proposes the approximation from real CQI data containing small scale fading to that containing only large scale fading to do prediction. The concrete correlation features and the difference between the approximation and the original data are all analyzed. Simulation is done for confirmation. It shows that the approximate large scale CQI data is feasible and rational for prediction and ensuring AMC efficiency.

scholarly journals Mean Mutual Information Based Adaptive Modulation and Coding Mechanism for Cooperative Relaying in Wireless Systems

2013 ◽  
Vol 8-9 ◽  
pp. 593-602
Author(s):  
Mihaly Varga ◽  
Mihai Alin Badiu ◽  
Vasile Bota
Keyword(s):  
Mutual Information ◽  
Adaptive Modulation ◽  
Prediction Method ◽  
Link Adaptation ◽  
Cooperative Relaying ◽  
Cooperative Transmission ◽  
Adaptive Modulation And Coding ◽  
Adaptation Algorithm ◽  
Time Frequency ◽  
Target Block

We propose a link adaptation algorithm for cooperative transmissions in an OFDMA-based wireless system. The link adaptation method selects the transmission type (cooperative or non-cooperative), the modulation orders and amount and type of redundancy required to ensure a target block error rate at each phase of the cooperative transmission. The above parameter-values are chosen so as to minimize the number of occupied time-frequency radio resources required to transmit the K-bit log data block. The algorithm employs a BLER performance prediction method based on mutual information. The proposed link adaptation algorithm has linear complexity, but still provides a very good performance, as shown by simulation results.

Sign in / Sign up

Export Citation Format

Share Document