Research of the frequency planning methods for cell networks based on lte and gsm technologies

I.M. Kuz, Z.M. Kharkhalis, P.O. Guskov, O.A. Lavriv

Lviv Polytechnic National University

Modern researches in field of mobile network depend on network infrastructure in a specific region. Nowadays, the actual issue is reforming of the existing frequency range for LTE deployment. The most common band is 900/1800 MHz, which in usual licensed for the GSM networks. It known that LTE net-work core can be easily integrated with the existing GSM infrastructure. The convergent base stations had been already known which can operate with GSM/LTE/WCDMA simultaneously. Therefore, the urgent task is implementation of radio interface based on spectrum sensing between different technologies in the same band. This work is devoted to building effective frequency planning networks for LTE technology on the existing GSM band. While making frequency planning of LTE technology, we take into account the presence coverage of existing GSM network. Thus, we consider two different methods of frequency planning: soft and fractional. Both of these methods of frequency reuse well described in LTE. In both cases, the whole frequency band divided into two groups. One of them used by the subscribers located inside the cell as well as on it edges, the other – only in-side the cell. Deploying LTE coverage on GSM spectrum may arise the situation when operating frequencies of GSM base station can fully interfere with one of the LTE bands. We propose modified method of soft frequency re-use, which lies in exception of conflict bands from an inside-cell frequency band. At the border of the cell, we propose to use coordinated service that is providing service to the subscriber by multiple base stations, in order to achieve higher throughput. This technology lies in synchronizing multiple base stations in time and frequency in their interaction via optical channel. Using a joint processing method, we obtain a significant increase in throughput at the border of the cell, which compensates some drawbacks of the soft frequency reuse method. One of the options for deploying LTE network is construction of a common network between several operators. It is a widespread practice these days and leads to the solution for a number of problems, which are connected, in particular, to the lack of spectrum for 3rd and 4th generation networks deployment. Given the global experience, we consider the following model of cooperation between operators: two or more operators carry out reforming of their own bands to release continuous frequency band, merging of which forms a common frequency band. From the set of architectural solutions, we chose two models in which we will be interested. Gateway Core Network – main principal of which lies in closer interaction in a network control segment and allows to install shared mobility management entities as well as common radio access network. Multi Operator Core Network – uses separate MME modules, which, in comparison to GWCN, allows to de-crease amount of service traffic in transport network and to simplify the setup of each core network. According to Ukrainian circumstances and the need of CAPEX reducing in the initial stage we propose to use a GWCN model.