MEASURING UPLINK INTERFERENCE IN RADIO SYSTEM, AND BASE STATION

Abstract: The invention relates to a method of measuring uplink interference in a cellular radio system, and a base station. The base station (BTS) comprises a floating transceiver and/or a transceiver provided with a diversity receiver, the transceivers being used for measuring the uplink interference, i.e., the interference of the traffic coming from a subscriber terminal (MS) to the base station (BTS). The uplink interference was previously measured with a spectrum analyzer at a base station site, which was laborious and expensive. The method and base station of the invention enable the uplink interference measurements to be made with specific equipments in the base station, and separate measurements at the base station site are in this respect no longer required.

Description: MEASURING UPLINK INTERFERENCE IN RADIO SYSTEM, AND BASE STATION The invention relates to a method of measuring uplink interference in a cellular radio system comprising in each cell at least one base station communicating with subscriber terminals in its area by one or more transceiv- ers, and which base station comprises at least one floating transceiver. The invention also relates to a method of measuring uplink interference in a cellular radio system comprising in each cell at least one base station communicating with subscriber terminals in its area by one or more transceivers, and which base station comprises at least one transceiver comprising a diversity receiver. The invention also relates to a base station in a cellular radio system comprising in each cell at least one base station, which base station comprises one or more transceivers, and which base station communicates with subscriber terminals in its area, and which base station comprises at least one floating transceiver. The invention also relates to a base station in a cellular radio system comprising in each cell at least one base station, which base station comprises one or more transceivers, and which base station communicates with subscriber terminals in its area, and which base station comprises at least one transceiver comprising a diversity receiver. In a cellular radio system, each cell comprises at least one base station communicating with subscriber terminals in its area via one or more transceivers. A base station controller controls the operation of one or more base stations. In cellular radio systems, user speech and data traffic is trans- mitted between a base station and a subscπber terminal by using traffic channels. In addition, different kinds of control messages and system information transmitted by means of control channels are needed between the base station and the subscriber terminal. The method and base station of the invention can be applied to any cellular radio system utilizing a TDMA system and/or an FDMA system. Today, different types of interference and interference measurements are of great importance to cellular radio systems, since many different types of systems are in use and an increasing number of new cellular radio networks are being built. Cellular radio system network designers, in particular, need tools for measuring the interference. A significant problem for the network designers is how to measure uplink interference in the cellular radio sys- terns, in other words, how to measure the interference of the traffic coming from the subscriber terminal to the base station. Information about the uplink interference is important when a new channel is being added to the cell, for example. The purpose is then to select the most suitable channel with a mini- mum amount of interference. The importance of measuring the uplink interference becomes even more stressed if the cellular radio systems begin to use automatic channel allocation. In the prior art, the uplink interference in a cellular radio system is measured over the entire width of the reception band by a spectrum analyzer at the site of a base station. The measuring is laborious and expensive, because it must be done at the base station site. If the interference is occasional and only appears at a certain time of the day, for example, it may take several hours or even days for a person to accomplish the measuring at the base station site. An object of the invention is to provide a new type of method of measuring uplink interference in a cellular radio system, and a base station for eliminating the above-mentioned prior art shortcomings. This object is achieved by the method of the invention, which is characterized by using at least one floating transceiver for measuring the uplink interference. Alternatively, the method of the invention is characterized by using at least one transceiver comprising the diversity receiver for measuring the uplink interference. The base station of the invention is characterized in that the base station comprises means for using at least one floating transceiver for measuring the uplink interference. Alternatively, the base station of the invention is characterized in that the base station comprises means for using at least one transceiver comprising the diversity receiver for measuring the uplink interference. The method and base station of the invention provide many advantages as compared with the prior art. Owing to the method and base station of the invention, separate measurements made with a spectrum analyzer are no longer required at the base station site, but the measurements are made by specific equipments in the base station. Consequently, expensive and difficult measurements requiring the presence of persons at the site are in this respect no longer needed. The equipments in the base station can meas- ure the interference from the desired channels or over the entire width of the reception band, and, as compared with the earlier measurements that required the presence of persons at the site, quite a long measurement time is possible, if required. It is a significant advantage of the method and base station of the invention that measuring the uplink interference does not dramatically disturb the normal operation of the base station. In the following, the invention will be described in more detail with reference to the accompanying drawings, in which Figure 1 shows a cellular radio system wherein the method and base station of the invention can be applied, Figure 2 shows a block diagram of a first preferred embodiment of the base station of the invention, and Figure 3 shows a block diagram of a second preferred embodiment of the base station of the invention. Figure 1 shows a cellular radio system wherein the method and base station of the invention can be applied. The cellular radio system comprises in each cell at least one base station BTS communicating by one or more transceivers with subscriber terminals MS in its area. A base station controller BSC controls the operation of one or more base stations BTS. In cellular radio systems, user speech and data traffic is transmitted between the base station BTS and the subscriber terminal MS by means of traffic channels. In addition, different kinds of control messages and system information transmitted by means of control channels are needed between the base station BTS and the subscriber terminal MS. The method and base station of the in- vention can be applied to any cellular radio system utilizing a TDMA system and/or an FDMA system. Block diagrams presented in Figures 2 and 3 are examples of the base stations of the invention, and they can be used in the GSM, DCS or PCS 1900 cellular radio systems. Figure 2 shows a block diagram of a first preferred embodiment of the base station of the invention. The base station of Figure 2 is called a sectored base station, i.e. the same base station includes several cells. In the GSM radio system, for example, each cell has a specific BCCH channel and specific traffic channel numbers. In the sectored base station, each cell has specific transceivers, specific antenna connection means, and specific anten- nas. The base station of Figure 2 comprises two sectors, i.e. the base station serves two different cells. Transceivers TRX1 and TRX2, antenna connection means AFE1 , a transmitter antenna ATX1 , a main receiver antenna ARX1 and a diversity receiver antenna ADRX1 are provided for a first cell. For a second cell there are provided transceivers TRX3 and TRX4, antenna con- nection means AFE2, a transmitter antenna ATX2, a main receiver antenna ARX2 and a diversity receiver antenna ADRX2. BCF is a base station control unit, and TRU is a transmission card connecting the base station to a base station controller via a link. Besides a transmitter part, all transceivers of the base station of Figure 2 include a main receiver and a diversity receiver. The diversity receiver is an accessory. The base station of Figure 2 also includes a floating transceiver FTRX and a connection unit FTS. The floating transceiver FTRX has the same properties as other base station transceivers, and it is connected to the antenna connection means AFE1 or AFE2 via the connection unit FTS. It is also known that the floating transceiver is used, for example, as fixedly installed in a cell to increase its capacity or as a redundant accessory in case of malfunctions of other transceivers. It is also known that the floating transceiver is dynamically used to increase capacity in a cell. In the method of the invention, the floating transceiver FTRX is used instead of, or along with, the normal operation for measuring the uplink interference. If the floating transceiver is a redundant accessory in the normal operation, it is for most of the time idle. In that case it can be used for continuously measuring the uplink interference for quite long periods. The floating transceiver measures uplink interference levels from the cell to which it is con- nected. The floating transceiver is tuned to the desired channels according to a command given by the base station control unit BCF, or the uplink interference is measured over the entire width of the reception band, if desired. The base station reports interference measurement results to the base station controller BSC. A list of channels that contain a minimum amount of interfer- ence or the interference levels of all channels can be sent as the results. If the floating transceiver is not idle, it will be released, after which the floating transceiver starts measuring the uplink interference. Besides a main receiver, the floating transceiver may also include a diversity receiver. The uplink interference can be measured solely via the main receiver or solely via the diversity receiver, or simultaneously via both receivers. The base station of the invention is characterized in that the base station comprises the means BCF for using the floating transceiver FTRX for measuring the uplink interference. The base station comprises the means BCF and FTRX for measuring the uplink interference either from the desired channels or over the entire width of the reception band. The base station comprises the means BCF for using the floating transceiver FTRX for measuring the uplink interference when the floating transceiver is idle. If the floating transceiver FTRX is not idle, the base station comprises the means BCF for releasing the floating transceiver FTRX from other tasks before it starts measuring the uplink interference. The floating transceiver FTRX comprises the main receiver and the diversity receiver. The base station comprises the means BCF and FTRX for measuring the uplink interference solely via the main receiver of the floating transceiver FTRX, solely via the diversity receiver, or simultaneously via the main receiver and the diversity receiver. The base station control unit BCF can be implemented by software with a signal processor or a general purpose processor, for example, or by using separate components, as it is obvious to those skilled in the art. The floating transceiver FTRX can be connected to either of the cells of the base station and it can measure the uplink interference characteristic of said cell. Since measuring involves the use of reception antennas of said base station cell, the measured uplink interference is identical to the interference detected by the receivers of the cell. Measuring the uplink interference does not dramatically disturb the normal operation of the base station. Figure 3 shows a block diagram of a second preferred embodiment of the base station of the invention. The base station of Figure 3 includes only one cell. The base station comprises transceivers TRX1 to TRX4, antenna connection means AFE, a transmitter antenna ATX, a main receiver antenna ARX and a diversity receiver antenna ADRX. BCF is a base station control unit and TRU is a transmission card connecting the base station via a link to a base station controller. Besides a transmitter part, all base station transceivers of Figure 3 include a main receiver and a diversity receiver. The diversity receiver is an accessory. The base stations are generally so designed that besides a main receiver, each transceiver may include a diversity receiver. These transceivers are generally similar except that both have a specific antenna. These anten- nas are physically disposed at different locations in order that a signal coming from the subscriber terminal to the base station would not simultaneously at- tenuate in the same manner both at the main receiver and at the diversity receiver. In reception, the base station uses either the main receiver signal or the diversity receiver signal, depending on which signal has a better signal-to- noise ratio. The choice takes place in a baseband part of the transceiver. In the method of the invention, the transceiver TRX1 comprising the diversity receiver is used for measuring the uplink interference. The uplink interference is measured via the diversity receiver of the transceiver TRX1 when the diversity receiver is idle. If the diversity receiver of the transceiver TRX1 is not idle, it will be released before it starts measuring the uplink interference. At the same time, the diversity amplification of the transceiver TRX1 is lost for the duration of measuring the interference. When the interference is measured, the diversity receiver is tuned to frequencies to be measured, and the uplink interference can be measured over the entire width of the reception band, if desired. The base station reports interference measurement results to the base station controller BSC. A list of channels with a minimum amount of interference or the interference levels of all channels can be sent as the results. During the uplink interference measurement, the main receiver of the transceiver TRX1 is used normally for call traffic reception. The base station of the invention is characterized in that it com- prises the means BCF for using the transceiver TRX1 comprising the diversity receiver for measuring the uplink interference. The base station comprises the means BCF and TRX1 for measuring the uplink interference via the diversity receiver of the transceiver TRX1. The base station comprises the means BCF and TRX1 for measuring the uplink interference either from the desired chan- nels or over the entire width of the reception band. The base station comprises the means BCF for using the diversity receiver of the transceiver TRX1 for measuring the interference when the diversity receiver is idle. If the diversity receiver of the transceiver TRX1 is not idle, the base station comprises the means BCF for releasing it from other tasks before it starts measuring the in- terference. The base station control unit BCF can be implemented by software with a signal processor or a general purpose processor, for example, or by using separate components, as it is obvious to those skilled in the art. Although the invention is described above with reference to the examples according to the attached drawings, it is obvious that the invention is not restricted thereto but it can be modified in many ways within the scope of the inventive idea presented in the claims. The preferred embodiments and other detailed solutions emphasize the advantages of the invention.

Claims: CLAIMS 1. A method of measuring uplink interference in a cellular radio system comprising in each cell at least one base station (BTS) communicating with subscriber terminals (MS) in its area by one or more transceivers (TRX1 to TRX4, FTRX) and which base station (BTS) comprises at least one floating transceiver (FTRX), characterized by using at least one floating transceiver (FTRX) for measuring the uplink interference. 2. A method as claimed in claim 1, characterized in that the uplink interference is measured over the entire width of the reception band. 3. A method as claimed in claim 1, characterized in that the uplink interference is measured when the floating transceiver (FTRX) is idle. 4. A method as claimed in claim 1, characterized in that the floating transceiver (FTRX) is released from other tasks, after which it is used for measuring the uplink interference. 5. A method as claimed in claim ^characterized in that the floating transceiver (FTRX) receives signals via a main receiver and via a diversity receiver and that the uplink interference is measured via the main receiver of the floating transceiver (FTRX). 6. A method as claimed in claim 1, characterized in that the floating transceiver (FTRX) receives signals via the main receiver and via the diversity receiver and that the uplink interference is measured via the diversity receiver of the floating transceiver (FTRX). 7. A method as claimed in claim 1, characterized in that the floating transceiver (FTRX) receives signals via the main receiver and via the diversity receiver and that the uplink interference is measured simultaneously via the main receiver and the diversity receiver of the floating transceiver (FTRX). 8. A method of measuring uplink interference in a cellular radio system comprising in each cell at least one base station (BTS) communicating with subscriber terminals (MS) in its area by one or more transceivers (TRX1 to TRX4), and which base station (BTS) comprises at least one transceiver (TRX1 to TRX4) comprising a diversity receiver, characterized by using at least one transceiver (TRX1) comprising the diversity receiver for measuring the uplink interference. 9. A method as claimed in claim 8, characterized in that the uplink interference is measured over the entire width of the reception band. 10. A method as claimed in claim 8, characterized in that the uplink interference is measured when the diversity receiver of the transceiver (TRX1 ) is idle. 11. A method as claimed in claim 8, characterized in that the diversity receiver of the transceiver (TRX1) is released from other tasks, after which it is used for measuring the uplink interference. 12. A method as claimed in claim 8, characterized in that the uplink interference is measured via the diversity receiver of the transceiver (TRX1). 13. A base station in a cellular radio system comprising in each cell at least one base station (BTS), which base station (BTS) comprises one or more transceivers (TRX1 to TRX4, FTRX), and which base station (BTS) communicates with subscriber terminals (MS) in its area, and which base station (BTS) comprises at least one floating transceiver (FTRX), characterized in that the base station (BTS) comprises means (BCF) for using at least one floating transceiver (FTRX) for measuring uplink interference. 14. A base station as claimed in claim 13, characterized in that the base station (BTS) comprises the means (BCF, FTRX) for measuring the uplink interference over the entire width of the reception band. 15. A base station as claimed in claim 13, characterized in that the base station (BTS) comprises the means (BCF) for using the floating transceiver (FTRX) for measuring the uplink interference when the floating transceiver is idle. 16. A base station as claimed in claim 13, characterized in that the base station (BTS) comprises the means (BCF) for releasing the floating transceiver (FTRX) from other tasks and after releasing, for using it for measuring the uplink interference. 17. A base station as claimed in claim 13, characterized in that the floating transceiver (FTRX) comprises a main receiver and a diversity receiver. 18. A base station as claimed in claim 17, characterized in that the base station (BTS) comprises the means (BCF, FTRX) for measuring the uplink interference via the main receiver of the floating transceiver (FTRX). 19. A base station as claimed in claim 17, characterized in that the base station (BTS) comprises the means (BCF, FTRX) for measuring the uplink interference via the diversity receiver of the floating transceiver (FTRX). 20. A base station as claimed in claim 17, characterized in that the base station (BTS) comprises the means (BCF, FTRX) for measuring the uplink interference simultaneously via the main receiver and the diversity receiver of the floating transceiver (FTRX). 21. A base station in a cellular radio system comprising in each cell at least one base station (BTS), which base station (BTS) comprises one or more transceivers (TRX1 to TRX4), and which base station (BTS) communicates with subscriber terminals (MS) in its area, and which base station (BTS) comprises at least one transceiver (TRX1 to TRX4) comprising a diversity receiver, characterized in that the base station (BTS) comprises means (BCF) for using at least one transceiver (TRX1) comprising the diversity re- ceiver for measuring uplink interference. 22. A base station as claimed in claim 21, characterized in that the base station (BTS) comprises the means (BCF, TRX1) for measuring the uplink interference over the entire width of the reception band. 23. A base station as claimed in claim 21, characterized in that the base station (BTS) comprises the means (BCF) for using the diversity receiver of the transceiver (TRX1) for measuring the uplink interference when the diversity receiver is idle. 24. A base station as claimed in claim 21, characterized in that the base station (BTS) comprises the means (BCF) for releasing the di- versify receiver of the transceiver (TRX1 ) from other tasks and after releasing, for using it for measuring the uplink interference. 25. A base station as claimed in claim 21, characterized in that the base station (BTS) comprises the means (BCF, TRX1) for measuring the uplink interference via the diversity receiver of the transceiver (TRX1).

Inventors: KASSINEN JUHA, KASSINEN, JUHA
Applicants: KASSINEN JUHA, NOKIA TELECOMMUNICATIONS OY, KASSINEN, JUHA
Application year: 1998
Main classification: H04Q7
IPC codes: H04B17, H04W24, H04W88