Capacity Expansion for Non-Uniform Spatial Traffic Distributions

This paper outlines key aspects that operators need to consider when expanding their radio access infrastructure to get a cost efficient production of wireless services. Two promising expansion paths are analyzed with respect to the achievable area throughput for an urban scenario. The first is considering a cellular evolution based on high speed packet access (HSPA) with multiple input multiple output (MIMO) technology in macro base stations. The other is a multi radio access (multi-access) environment where a HSPA macrocell layer without MIMO is complemented with IEEE 802.11a wireless local area network (WLAN) access points. When accounting for the difference in total cost for complementary base stations, the cellular evolution supports a higher average area throughput in downlink for low and moderate hot spot densities. The advantage decreases with macro base station site density so for higher hot spot and macrocell site densities the multi-access system is more favourable. For uplink the multi-access network in general supports higher capacity thanks to that the cellular evolution is limited by penetration losses for indoor users. Thus, depending on how densely an existing macrocell network is deployed and the targeted capacity in downlink and uplink, different expansion paths would bring the lowest cost of infrastructure.