An efficient handover measurement technique is proposed for millimeter-wave (mm-wave) cellular systems with directional antenna beams. As the beam synchronization signal (BSS) carries the cell ID and the beam ID in a hierarchal manner, handover events (interbeam handover and intercell handover) are distinguished at the physical layer. The proposed signal metrics are shown to be effective in detecting the beam boundaries and cell boundaries in mm-wave cellular systems, which allows to distinguish interbeam handover from intercell handover. The proposed handover measurement technique is shown to reduce the processing time significantly using the proposed signal metrics produced by the BSS.

In this letter, an estimation technique for multiple CFOs is proposed that uses the properties of the Zadoff-Chu (ZC) sequence. After initial estimation of multiple CFOs by using the properties of the ZC sequence, accurate estimates are obtained in the proposed technique by an iterative procedure. The proposed technique can be applied to LTE-based CoMP systems where ZC sequences are used to generate synchronization signals in downlink and random access preambles in uplink.

In this paper, two receive beamforming techniques (Method 1 and Method 2) are proposed for a mobile station (MS) with multiple antenna arrays in an OFDM-based millimeter-wave (mm-wave) cellular communication system. Since the MS in mm-wave cellular communication requires fast processing due to its frequent movement and rotation, a receive beamforming technique with reduced computation complexity and processing time is proposed in Method 2. Of particular interest, estimation techniques for 2-dimensional (2D) direction-of-arrivals (DoAs) corresponding to each cell ID are proposed for uniform circular arrays (UCAs) and uniform rectangular arrays (URAs). Also, a cell selection technique for MSs with multiple antenna arrays is described that use the candidate cell IDs and parameters estimated for all antenna arrays to provide combining gain in addition to array gain in multipath channels. The proposed beamforming techniques are evaluated by computer simulation using a simple model of amm-wave cellular communication system with 3-dimensional spatial channel model (3D SCM).

In this paper, an interference rejection combining (IRC) technique is proposed for SFBC-OFDM cellular systems that exhibit multiple carrier frequency offsets (CFOs). The IRC weight and the corresponding value for CFO compensation in the proposed technique are obtained by maximizing the post-SINR, i.e., minimizing both the interference signal and inter-channel interference (ICI) terms caused by multiple CFOs. The performance of the conventional IRC and proposed IRC techniques is evaluated by computer simulation for an SFBC-OFDM cellular system with multiple CFOs.