Mobile - Cellular & PCS Networks

This note describes how ATDI software can be used across current cellular and PCS technologies using TDMA and CDMA modulation to optimise and roll out networks. Such networks can give expansive coverage such as is typical in the 900MHz bands or can be small cell and micro-cell providing footprints of only a few hundred metres. The methods and sib-tools within tools such as ICS Telecom have come from our work with various customers. These customers have either used our tools or have contracted ATDI to carry out work on their behalf to furthers their development of their cellular or PCS networks.

General Cellular and PCS Networks Planning Methods

The following general modelling methods have application in cellular and PCS networks and are included in ATDI planning tools.

• The ability to compute the coverage of ground area from a given transmitter type and specification to a given receiver type and specification.
• The ability to compute the degree of interference suffered by both mobiles (down link) and base stations (up link) from all sources on the same or adjacent channels.
• The counting of mobile population covered under a transmitter footprint with the addition of an irregular polygon limit.
• The counting of area under a transmitter footprint but showing results over a variety of different urbanisation categories including roads, urban and suburban areas with the addition of an irregular polygon limit.
• The ability to link planning tools via either local or wide area computer networks to develop the cellular or PCS network using a number of planners each with privilege to change their own zone yet compute the effects of those adjacent.
• The ability to link the planning tools via an Open DataBase Connectivity protocol to external databases such as Oracle or MS Access allowing the sharing of engineering data across a multi-discipline project team.

Specific Cellular and PCS Networks Planning Methods

The design and subsequently the roll our of cellular and PCS networks to cover both dada and voice is a well established process. There is however great scope for automation in the methods and for optimisation of the engineering design to critically engineer the network to meet the customer requirements with the minimum base station and antenna system resources both initially and as the network develops. The specific methods noted below are some of the many tools employable to ensure that the planning team produces the most cost effective system.

The coverage calculated can be filtered to only display on specified ground use types such as roads and railways. This then allows the planner to focus on the desired target user for the service. Similarly interference calculations over rural or open areas away from that target user can be ignored or reduced in consideration during automatic frequency planning. Several views are possible once a coverage computation from a given sites or radio base station has been made. The best server view shows where on the ground mobiles would vote or register on the basis of signal strength. The simultaneous communications view shows which areas on the ground benefit from signal from several sites.

Once coverage has been assessed the operating frequency of the base station can be assigned automatically from a frequency list. Frequency group planning can also be set fixing groups of channels to particular base stations. This assignment is done primarily in the talk out path by selecting by a genetic exclusion method the best frequency or group of frequencies to maximise the C/I ratio experienced by the mobile users.

The computation of the traffic capacity of the network will of course be dependent on the number of subscribers served by a particular base station. Traffic analysis on the basis of best server or on forced server can be computed using methods such as Erlang B. The traffic demand can be made up in a demand file directly in the planning tool and various demand profiles can be used simulating the development of the user population with time.

The ability to connect the planning tool, to the network management system, and to provide continuous performance assessment at all stages of network availability, ICS Telecom can be used to command reconfiguration of the network to account for changing scenarios. This is an area where we would be happy to discuss additional possibilities in this field.