A modified directional frequency reuse plan based on channel alternation and rotation

In a previous work (see Nguyen, V.A. et al., IEEE Vehicular Technology Conference, 2001), we presented a novel channel alternation and rotation (CAR) scheme that coordinates channel assignment with antenna directivity. In CAR, each cell type is allocated an extra channel set that provides the network designer the flexibility to alternate and rotate channels according to a nearest front lobe interference avoidance strategy in order to enhance the cochannel interference ratio (C/I). CAR relaxes the constraints assumed in conventional reuse plans to allow deployment of smaller, unconventional reuse cluster sizes based on C/I requirements, thus increasing frequency reuse efficiency. We present a new reuse plan in which 2 extra channel sets are allocated to each cell type and assigned according to CAR strategy. This reuse plan, referred to as 2×(3+2), increases channel capacity by 20% in comparison with the conventional 4×3 reuse plan which still provides signals above the minimum acceptable C/I margin. The 2×(3+2) reuse plan is simple and can be implemented without costs.