The importance of in-building solutions in third-generation networks

摘要

Providing good in-building coverage plays an important role in attracting and retaining mobile subscribers. Ordinarily, coverage from the macro network extends into buildings but should be complemented by dedicated in-building systems. Greater data capacity and the ability of third-generation networks to provide high-speed data services increase the demands put on the cellular network. Subscribers have great expectations regarding third-generation services. Therefore, when introduced, the new services must (at very least) be available everywhere second-generation services can be found. Notwithstanding, many third-generation networks deployed to date have been designed primarily to provide good coverage in outdoor environments - not inside buildings. As a consequence, users of early implementations of wideband code-division multiple access (WCDMA) rate third-generation services poorly compared to second-generation services. Besides guaranteeing better quality of service (QoS), dedicated in-building systems enable operators to catch roaming subscribers - most roaming subscribers have automatic public land mobile network (PLMN) selection, which means that if the regular connection is lost, their phone automatically selects the best available PLMN. Operators who provide dedicated in-building coverage in key locations, such as airports and train stations, can thus catch these high-value roaming subscribers. The implementation of dedicated in-building coverage in CDMA-based networks also offloads the macro system, thereby increasing overall system capacity. In other words, operators can, with minimum investment, continue to use existing networks to serve a growing number of subscribers. This gain in capacity means that operators can put off splitting cells and thereby substantially reduce costs of network expansion. In particular, it is more beneficial to deploy dedicated in-building coverage systems in third-generation CDMA-based networks than in time-division multiple access (TDMA) networks. Interesting solutions for deploying in-building coverage in WCDMA networks make use of distributed radio base stations (DRS) and passive distributed antenna systems (DAS). These solutions reduce overall costs by lowering transmission costs, increasing trunking gain, and by sharing RBS equipment.