Nov 9, 2016

A lot of schemes are proposed to exploit the transmit diversity. Distributed antenna systems (DAS) constitute one of the most attractive schemes to efficiently achieve the stringent quality of service demands of next generation wireless networks. A particular project investigates MISO assisted different transmission techniques used in DAS and the performance of downlink multi-cell DAS in terms of capacity improvement using SINR for different transmission scheme. A system level simulation tool is used to analyse the performance. Here, the aim of this research is to assess the applicability of a Repeater connected to a Distributed Antenna System (DAS) for improving indoor capacity in UMTS radio network (2100 MHz). A guarantee of sufficient coverage and capacity for in-building areas constitutes a considerable issue in topology planning, because in both links, indoor users produce high interference to the outdoor network due to significant indoor propagation losses. Presented configuration effectively exploits effectively a Repeater system that amplifies the signal from the outdoor network and delivers it for indoor locations through distributed antenna system. Implementation of the analysed Repeater system is straightforward as it does not require usage of separate carrier. Moreover, any separate scrambling codes do not have to be dedicated either. Conducted measurement campaigns reveal improvement of radio conditions due to repeater implementation that results in 35% gain of downlink capacity for indoor locations. The Distributed Antenna system (DAS) usually use an external, directional antenna to collect the best cellular signal, which is then transmitted to an amplifier unit which amplifies the signal, and retransmits it locally, providing significantly improved signal strength. The more advanced models often also allow multiple cell phones to use the same repeater at the same time, so are suitable for commercial as well as home use. In cellular communication, repeaters are classically used for providing coverage in dead spots, which mainly constitute hardly accessible areas for regular base station deployment. In most of the scenarios, utilization of repeaters is very cost effective, as it decreases the number of required base stations. Moreover, in it was presented that properly deployed and configured repeaters constitute an effective capacity enhancement in CDMA-based networks. Hence, repeater systems can provide flexible and inexpensive solutions for varying traffic conditions, for hotspots (i.e. Areas with high capacity requirements), and also for serving indoor users. Typically, cellular networks providing service in majority of indoor locations must support high capacity requirements due to expected presence of active business subscribers using packet-based applications. Performance of the WCDMA (Wideband Code Division Multiple Access) network without specified approach supporting indoor traffic is limited, because high power required by indoor users produces interference that naturally limits the overall network capacity. Moreover, appropriate operation of HSDPA (High Speed Downlink Packet Access) in UMTS (Universal Mobile Telecommunication System) requires favourable radio conditions, which in indoor environment can be achieved only when dedicated antenna system is used. Therefore, from early stages of topology planning, indoor traffic with associated capacity requirements needs to be carefully considered.

Posted at 11:42 pm by samsolong


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