networks


Considerations for network optimization


In issue 13, TETRA Today took a look at some of the considerations involved in planning a TETRA network. Once that design is complete and base stations are deployed, the optimization process can begin. Tim Guest reports


Increasingly, there


are processes being incorporated into TETRA networks to continuously monitor


performance to


ensure no problems are arising


Drive testing and monitoring the network are the two key optimization activities, which need to be performed. “Typically, what happens after the rollout is completed”,


W


says Jyrki Koski, chief executive officer at Creowave, “is quite a lot of testing for network performance in different kinds of scenarios, with drive tests playing a typical and crucial part of this, with additional different kinds of testing taking place related to capacity handling.” Viv Williams, Motorola project director for Norway,


confirms that an “extensive drive test programme” will normally be performed to confirm the actual service area and confirm that calls can be successfully made. Taking this part of the discussion further, David Taylor,


lead consultant at Mason, adds that to optimize effectively you need to look at the whole network and not just the coverage provided by a single site. As part of the optimization process, building up a picture of what adjacent cells are available to a particular cell is a key factor. Broadcast messages


16


ith the network deployed, optimization is the crucial next, and ongoing, process, which will fine tune coverage and capacity issues.


from each cell indicate these details so that a picture of cell signal strengths and cell quality can be created. Tis is part of the basic protocol – each site radiates its


neighbours and each radio builds up a list of the quality of the neighbours. Tere is a design/optimization overlap here, as network designers then decide what neighbours are on that list. So, if an infill site, just for capacity, is required to bolster the network design, it might also be included in certain neighbour lists, enabling adjustments to be made as to how the network behaves. If, for example, you have an air-to-ground network, you might need your neighbour list to adjust how your airborne radios operate, and which terrestrial cells are seen by individual radios. Conversely, you might also determine which radios operating on the terrestrial network are seen from above. But neighbour lists are essential in the optimization process


when drive testing. “As well as having coverage data”, says Taylor, “operators must have the right neighbour lists, as well. With the wrong neighbour list a drive test radio (and, in turn, an operational radio) might skip over one cell and go to one that is further away, and if a radio were to make such a choice,


TE TRA TODAY Issue 14 2013


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