Backhaul Traffic Model in Central Solutions
The backhaul traffic of the central solution includes the uplink and downlink traffic in the macrocell and small cells. The uplink throughput of a small cell is denoted by THcentra small-up
= 0.04 ◊ Bsccentra ◊ Ssccentra, where Bsccentra is the bandwidth of a small cell and Ssccentra is the average spectrum efficiency of a small cell [11]. The downlink throughput of a small cell is calculated by THcentrasmall-down = (1 + 0.1 + 0.04) ◊ Bsccentra ◊ Ssccentra, which is transmitted through the S1 interface of backhaul networks. The uplink throughput of a macrocell is denoted by THcentra macro-up = 0.04 ◊ Bmccentra ◊ Smccentra, where Bmccentra is the macrocell bandwidth and Smccentra is the average spectrum efficiency of a macrocell [10]. The downlink throughput of a macrocell is calculated by THcentramacro-down = (1 + 0.1 + 0.04) ◊ Bmccentra ◊ Smccentra, which is transmitted through the S1 interface of backhaul networks. Assume that the backhaul traffic is balanced in every small cell. The total number of small cells in a macrocell is configured as N. The total uplink backhaul throughput of the central solution is calculated as THcentra sum-up = N ◊ THcentra small-up + THcentra macro-up and the total downlink backhaul throughput of the central solution is calculated as THcentra sum-down = N ◊ THcentra small-down + THcentramacro-down. As a consequence, the total backhaul throughput of the central solution is summed as THsum centra = THcentra sum-up + THcentra sum-down