Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Reexamination Certificate
1998-06-24
2001-06-26
Hunter, Daniel (Department: 2684)
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
C455S067700, C455S063300, C455S445000, C455S446000, C455S423000
Reexamination Certificate
active
06253065
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method of estimating the amount of communications traffic that would be routed via a transceiver installed at a proposed transceiver location within the coverage area of an existing communications network. The invention has particular utility in relation to determining the most suitable location for, and characteristics of, a microcell-providing transceiver prior to its installation in a cellular telephone network.
2. Related Art
The last few years have seen a strong growth in the use of mobile telephones. Initially, each network operator enabled a mobile telephone service by installing a number of transceivers spaced around the region in which the service was to be made available. These transceivers typically had a range of between one kilometre and several tens of kilometres. In order to maximise the number of simultaneous calls that could be handled by the network, each transceiver was arranged to operate at a set of frequencies different from the frequencies used by each of its neighbours.
Further growth in the number of mobile telephone users meant that network operators had to divide the cells surrounding the transceivers into a plurality of sectors. Again, the frequencies allotted to the different sectors were chosen to be different from those used in neighbouring sectors. By decreasing the size of the areas in which a given set of frequencies was used, the network operators were able to further increase the capacity of their network.
Nevertheless, particularly in urban areas, even this increase in capacity has not been sufficient to cope with the rising demand. Hence many network operators are now installing low power radio transceivers which handle calls in progress within 100 or 200 metres of the transceiver. These low power transceivers are most usefully employed in areas where the number of calls made is exceptionally high, e.g. at railway stations or in shopping centres.
In order for a newly installed low power radio transceiver to be as effective as possible, it is important to position it and configure its characteristics so that it handles as many calls as possible. One example of a characteristic that can be controlled is the size and shape of the coverage area served by the transceiver.
Many conventional techniques for choosing the best location for a additional transceiver involve identifying the sectors or cells of the network which are heavily loaded and then intuitively guessing a number of possible locations for a transceiver from topographical maps of the local area. Having identified such candidate locations, traffic measurements can be made at each of the locations and the most suitable one determined.
One method that might be used to determine the number of calls that would be handled by a transceiver placed at one of the candidate locations would be to place, at the candidate location, an apparatus which emulates most of the functions of an operational transceiver but which is unable to have calls handed over to it. Such an apparatus could be set up to communicate to a mobile switching centre the strength of signals from nearby mobile units. By analysing the data received, the number of calls which would have been routed via the transceiver had it been fully operational can be determined. An example of this technique is seen in International Patent Application WO 96/35305.
However, the present inventor has realised that such a method and apparatus is unnecessarily time-consuming, complex and expensive.
SUMMARY OF THE INVENTION
According to a first aspect of the present invention, there is provided a method of estimating the amount of communications traffic that would be routed via an additional transceiver installed at a candidate transceiver location within the coverage area of a communications network having one or more network transceivers for providing wireless communication between the network and mobile communication units, the mobile units being operable to send reception data concerning downlink reception to the network, said method comprising the steps of:
operating a transmitter to transmit an interference signal from said candidate location to interfere with reception by mobile units within range of the transmission; and
analysing at least reception data concerning downlink reception during periods associated with transmission of said interference signal to find a measure indicative of the amount of communications traffic affected by said interfering transmission; and thereby estimating the amount of communications traffic that would be routed via said additional transceiver installed at said proposed location. Although early mobile telephone network standards (e.g. Total Access Communications System, or TACS) did not require mobile phones using the network to transmit any data relating to the quality of the signals they were receiving, more recent telephone network standards (including the Groupe Speciale Mobile (GSM) standard used across Europe and in Japan) require data concerning the quality of reception to be transmitted by the mobile phone to the network (where that data is then passed on to mobile switching centres). It is likely that future mobile telephone networks will also include such a reception data transmission and forwarding capability. Future mobile networks may also store the reception data. The present inventor has realised that by transmitting an interfering signal from the proposed location of the low power transceiver, the call monitoring capability already provided in the network can be used in establishing the number of calls that would be routed via a transceiver placed in that location.
Thus, the present invention provides a method allowing the determination of the number of calls that would be routed by a transceiver at a proposed location, which is furthermore economical and easy to use. Because it is economical and easy to use more candidate locations can be evaluated than has hitherto been possible, thereby improving the estimate of the best location for a additional transceiver.
Preferably, said interfering signal transmission step comprises transmitting said interfering signal for one or more spaced time periods, each being less than ten seconds in duration.
By limiting the interfering signal to bursts of short duration, the degradation in the quality of service provided to the customers of the network can remain within acceptable bounds. Clearly, the shorter the duration of each burst, the less noticeable is the effect on the customer's service. Nevertheless, the burst must be of a duration which is sufficiently long to cause a noticeable effect in the data concerning downlink reception. A preferred duration is less than 2.5 seconds, most favoured durations lie between 0.75 and 1.25 seconds.
In preferred embodiments of the invention, said network comprises a plurality of network transceivers, each being allotted one or more frequency bands, and communicating with mobile units currently routed via them by transmitting and receiving signals within said frequency bands; and
said transmission step comprises transmitting a signal to interfere selectively with one or more frequency bands allotted to respective chosen transceivers and thereby estimate the amount of communications traffic which would be routed via the transceiver installed at said proposed location instead of being routed via one or more chosen transceivers.
The method of the present invention becomes more useful, if, in addition to finding the amount of traffic which will be routed via the additional transceiver, it is also established from which of the neighbouring cells that traffic would be taken. This enables a network planner using the method of the present invention to route traffic away from a congested cell in the network.
Another preferred embodiment of the present invention involves a method where said transmission step comprises:
transmitting a first interfering signal having a first power;
transmitting a second interfering signal having a se
British Telecommunications public limited company
Gantt Alan T.
Hunter Daniel
Nixon & Vanderhye P.C.
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