Cost Efficient Deployment of Heterogeneous Wireless Access Networks

As data applications become more popular in mobile networks, usage patterns will be different from mobile telephony. Demand for higher bit rates is found in certain areas ("hot spots"), whereas the requirement for wide area coverage remains. Previous work has shown that using classical cellular hot-spot techniques (e.g., micro-cells) with a single radio access technology imply high-cost solutions. Instead, combining several, carefully chosen, access technologies in an efficient manner, leads to reduced infrastructure related costs while retaining a sufficient quality of service. In this paper, we estimate the user data rates achievable by complementing an urban macro cellular high speed packet access (HSPA) system with different hot spot solutions. When deployed at comparable cost levels, "dense macro", micro, and pico HSPA base stations yield a similar performance in downlink. Thanks to more spectrum bandwidth, IEEE 802.11a WLAN supports higher data rates in downlink both on average and for the lower percentiles of users. For the uplink, which in principal is noise limited already with a few hot spots deployed, indoor (pico and WLAN) base stations outperform outdoor systems, which are subject to severe propagation losses for indoor users.