In-Band Interference Effects on UTRA LTE Uplink Resource Block Allocation

Abstract

In this paper we investigate the impact of in-band interference on the uplink multiple access of UMTS Terrestrial Radio Access, long term evolution (UTRA LTE). In- band and out-of-band interference arise as a result of transmitter imperfections. Out-of- band, or adjacent channel, interference can be controlled by a spectral shaping filter. However, the shaping filter cannot control the leakage within the system bandwidth, and the resulting leakage can interfere with other users' transmission in the uplink multiple access. The situation is emphasized when the resource block allocation size is small, and when the interfering signal is received at higher power spectral density (PSD). The effect of frequency offset and different PSD level from the UE interferers to a victim UE is studied. The impact on different UE resource block size allocation is also investigated. The results are obtained from an LTE uplink link level simulation. It is shown that a significant SNR degradation is observed at the victim UE with smaller resource block size, when evaluated in a realistic channel. Considering that the frequency offset can be maintained below 200 Hz and PSD level offset below 10 dB, the SNR loss at 10% BLER target is less than 1 dB.