Handover Sequences for Interference-Aware Transmission in Multicell MIMO Networks

Providing cell-specific reference signals is a basic requirement for advanced transmission techniques reducing the inter-cell interference in the mobile radio network. In this paper, we introduce so-called handover sequences. They consist of a comb cyclically shifted in the frequency domain to identify the cells. Orthogonal sequences in time domain are used to identify the antennas within a cell. The scheme occupies few OFDM symbols per coherence interval. Sequence assignment to the cells follows a classical frequency-reuse scheme. Detection is easily implementable. With these sequences, the frequency-selective multi-cell channel can be identified with high precision also at the cell edge. We demonstrate that handover decisions are more reliable and channel estimation errors are reduced by more than a decade compared to the reference signals provided in 3GPP LTE Release 8.