On the Impact of Inter-Cell Interference in LTE

While intercell interference coordination (ICIC) for the downlink of multi-cell systems in general and orthogonal frequency division multiple access (OFDMA) networks in particular has been extensively studied, the uplink has received less attention. For the uplink, the impact of ICIC on the overall system throughput ("the ICIC gain") must be analyzed in a system model that captures specific constraints such as power limitation and the behavior of other radio resource management functions including scheduling, fast packet retransmissions by means of hybrid automatic repeat requests (HARQ), power control and adaptive modulation and code rate selection. In this paper we investigate the ICIC gain for the uplink of the 3GPP long term evolution (LTE) system and find that this gain much depends on the employed traffic model. Specifically, for non greedy (sometimes termed "non full buffer") traffic sources, HARQ and link adaptation are able to compensate the effect of intercell collisions and therefore the real ICIC gains are typically smaller than those reported based on full buffer models assuming greedy traffic. We expect that our findings provide useful insights for the system design of ICIC schemes.