Cell Optimisation - 4 days

The range of GSM parameters affecting the operation of a network is extensive and the network operator can be in command or at the mercy of these parameters. This course is designed to assist operations engineers to optimise the GSM network for a balance of maximum capacity and quality of service to the customer. A good knowledge of the air interface is necessary for attendance on this course which is centred around a series of exercises in optimising a network of cells. These exercises are performed in teams, the teams then presenting their solutions to the remainder of the class.

The course examines the typical working capacities for urban area 4/12 frequency reuse for various grade of service and how this impacts upon the dimensioning of control channels and dedicated channels and location areas. The GSM parameters broadcast on the BCCH and SACCH are then considered and problems on the settings of these parameters are addressed for a range of circumstances.

The course covers baseband and synthesiser frequency hopping in detail and the GSM parameters which determine hopping modes. The C/I advantages of hopping are covered, and trading -off of this C/I advantage to achieve an increased capacity. This leads to current methods of tighter frequency reuse including the Ericsson MRP - multiple reuse patterns and the Nortel FR - fractional reuse, both of which depend upon the C/I gain of hopping. The problem of adjacent channel and co channel interference and the frequency planning methods with the tighter reuse to avoid this is considered in detail.

The course goes on to consider increasing capacity through the use of micro and pico cells and gives problems to be solved in the siting, parameter setting and frequency allocations for these.

The 4/12 frequency reuse network. Maximum attainable capacity E/km2 for required G.O.S. Current minimal cell spacing. Working C/I. Frequency allocations. Adjacent and co-channel interference considerations. Rayleigh fading. Time dispersion. Exercises in capacity v G of S.

System Information. Parameters on the BCCH and SACCH - settings for optimal working. LAI - considerations of the number of LA¹s and The paging load. BSIC problems borrowing¹ NCC¹ s. Cell Channel description. RACH control and it use for congestion control. Access Classes and congestion control. Control channel description dimensioning of control channels to meet the traffic demand.

Handovers Quality handovers. Interference Handovers. Power Budget Handovers. Handover Margin. SDCCH Handovers. Optimising for handover success - hreqave and hreqt considerations. Directed retry - congestion relief handover. Exercises in Handover Parameter Optimisation.

Frequency Hopping. Synthesiser hopping - advantages and disadvantages - what can and cannot be done. Baseband hopping - advantages and disadvantages - what can and cannot be done. The use of the GSM hopping parameters - setting them for what you require. Cyclic or pseudo random? Operational C/I gain with hopping. Improved reliability of service (handovers, slow moving subscribers Rayleigh fades)

Using Hopping to Increase Capacity. The Ericsson MRP method. 12/8/8/8 MRP Baseband Hopping. Capacity gain. MRP cluster patterns. Adjacent channel interference. Frequency allocation. Frequency channel release. Exercises. 12/9/6/4 MRP Baseband Hopping. Capacity gain MRP cluster patterns. Adjacent channel interference. Frequency release. Frequency allocation. Exercises. The Nortel FR method - hopping using synthesiser Hopping. Capacity gain. Frequency reuse cluster patterns. Adjacent channel interference. Frequency channel release. The allocation of frequencies. Exercises

Integrating Micro and Pico cells into the macro network. Typical micro and pico cell separation. Frequency allocations to micro and pico. Minimum Coupling Loss considerations. Increasing capacity. Path loss, fading and ISI considerations. Cell selection considerations - setting the parameters optimally. Handover considerations. Micros and FR Exercises in micro cell optimisation within a macro network.