Abstract
Heterogeneous cellular networks (HetNets) consist of different tiers of base stations (BSs) to meet the ever-increasing mobile traffic demand. Due to the random deployment of BSs, Poisson point process (PPP) is often used to model the BS distribution. However, low power small cells are usually clustered around the popular areas, and PPP can not reflect such a feature. To this end, we in this paper consider base station (BS) cooperation and analyze user rate and energy efficiency of HetNets based on a Poisson cluster process (PCP). A calculable formula for the average data rate (or spectral efficiency) and its approximated closed form are derived. Based on this closed form, a power minimization solution with certain spectral efficiency constraint is proposed, and the optimal cooperation radii are derived. Furthermore, we analyze spectral efficiency under a limited number of cooperative BSs in a two-tier network. Finally, we propose a range expansion (RE) scheme and examine the impact of this scheme. The theoretical analyses are verified by simulation results.
Highlights
Comprising macro base stations (BSs) overlaid with dense low power BSs [1], heterogeneous networks (HetNets) are being deployed to meet the rapid growth in data demand from wireless users, especially those users at the edge of macro cells
1.2 Contributions The main contributions of this paper are as follows: (1) a computationally efficient formula for spectral efficiency is derived under the Poisson cluster process (PCP) model, and approximated as a closed form; (2) a comprehensive comparison with the corresponding Poisson point process (PPP) results is carried out; (3) a power optimization scheme is proposed by optimizing the cooperative radius of each tier; and (4) a scheme based on a limited number of cooperative BSs and a range expansion (RE) strategy are proposed, which can ease the load of macro BS and enhance the network EE
3.1 Poisson cluster process (PCP) A Poisson cluster process (PCP) consists of two kinds of point processes: the parent points in each tier following homogeneous Poisson point process (PPP) with the density λp,k form the centers of the clusters, while the daughter nodes are scattered around cluster centers
Summary
Comprising macro base stations (BSs) overlaid with dense low power BSs ( small cells) [1], heterogeneous networks (HetNets) are being deployed to meet the rapid growth in data demand from wireless users, especially those users at the edge of macro cells. References [16, 17] studied the performances of cross-tier cooperation scheme based on the PPP network model, and the numerical results illustrate that such a cooperation strategy can significantly boost ergodic capacity and reduce outage probability. 1.2 Contributions The main contributions of this paper are as follows: (1) a computationally efficient formula for spectral efficiency is derived under the PCP model, and approximated as a closed form; (2) a comprehensive comparison with the corresponding PPP results is carried out; (3) a power optimization scheme is proposed by optimizing the cooperative radius of each tier; and (4) a scheme based on a limited number of cooperative BSs and a range expansion (RE) strategy are proposed, which can ease the load of macro BS and enhance the network EE.
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