mately 90% at 5 MHz bandwidth with an AMR 12.2 kbps codec. Semi-persistent resource allocation is described in more detail in Section 10.6.2.2. CQI overhead As EUTRA is based on the OFDMA scheme, in LTE system, the channel-dependent scheduling can be conducted in both time and frequency domains. To achieve maxi- mal frequency domain scheduling gains in DL, each UE has to measure CQI in the frequency domain for all PRBs across the whole bandwidth and report the informa- tion to eNodeB for link adapta-tion and scheduling decisions. In practice, the feasible CQI feedback resolution in the frequency domain is limited by the UL control over- head related with CQI feedback, which may become prohibitively large, especially © 2009 by Taylor & Francis Group, LLC Long Term Evolution: 3GPP LTE Radio and Cellular Technology with VoIP traffic, where the number of supported users may be large. Therefore, CQI feedback should be reduced both in time and in the frequency domain to keep the UL control overhead at a reasonable level. The quantity of the reduction of CQI feedback in the time domain depends on the velocity of a user; for example, at 3 km/h the feasible CQI update rate for VoIP traffic is 5-10 ms. For this traffic, the impact of the CQI update rate is not that crucial, as due to the delay limitations of the traffic, the time domain scheduling gains are rather limited. When reducing CQI feedback in the frequency domain, the challenge is how much it could be reduced while maintaining the benefits of frequency domain scheduling. A simple method to reduce CQI feedback in the frequency domain is to relax CQI measurement granularity in the frequency domain and calculate one CQI feedback over N consecutive PRBs. Additionally, frequency selective CQI feedback schemes have been adopted by 3GPP, such as the best-M average scheme, where the UE reports only the average CQI for the M CQI blocks having the highest CQI value and indicates the position of those M blocks within the band- width (wideband CQI for the whole band-width is