METHOD OF CONTROLLING AN AUTONOMOUS DEVICE, E.G. A REPEATER, AND AN AUTONOMOUS DEVICE

Abstract: The invention relates to a method of controlling an autonomous device and to an autonomous device. Autonomous devices are for instance home repeaters (110) and home base stations (130). The autonomous device (110, 130) operates at the spectrum (200, 202) of at least one cellular radio network. The autonomous device has a bi-directional radio connection (170, 172) to a subscriber terminal (140, 142). The autonomous device (110, 130) automatically and dynamically selects the frequency to be used in the bi-directional radio connection (170, 172). The invention is characterized in that the autonomous device (110, 130) is directed to use certain parts (210, 220) of the spectrum (200, 202) of at least one cellular radio network when selecting the frequency.

Description: METHOD OF CONTROLLING AN AUTONOMOUS DEVICE, E.G. A REPEATER, AND AN AUTONOMOUS DEVICE FIELD OF THE INVENTION The invention relates to a method of controlling an autonomous de- 5 vice which operates at a spectrum of at least one cellular radio network and which has a bi-directional radio connection to a subscriber terminal and which automatically and dynamicaiiy selects the frequency to be used in a bidirectional radio connection. 10 BACKGROUND ART One prior art radio system is the DECT system that has a bidirectional radio connection between a fixed part and a portable part. The system operates at frequencies ranging from 1880 to 1900 MHz, and uses 10 carrier waves. The channel used on each connection is dynamically selected 15 before use. Thus several devices of the DECT system can operate simultaneously in the same area without interfering with one another. Operators, in turn, wish to utilize existing cellular radio networks when offering new services to their customers. It is also advantageous for the customer to be able to use an existing subscriber terminal for new services. 20 Figure 1 shows autonomous devices 110, 130. An autonomous device can be a home repeater 110 or a home base station 130. The home repeater 110 has a bi-directional radio connection 160 with a base station 100 of the cellular radio network, located in the area. The home repeater transmits the bidirectional radio connection 160 onwards to the subscriber terminal using a bi- 25 directional radio connection 170. Thus a user 150 may take along a subscriber terminal 140 when moving in the coverage area of his own home repeater 110. There is a connection 162, for instance a normal telephone connection or an ISDN connection, from the home base station to a public switched telephone network 120. The home base station 130 transmits the connection 162 30 to the subscriber terminal 142 using a bi-directional radio connection 172. The user 152 can take along the subscriber terminal 142 when moving in the coverage area of his own home base station 130. In both cases the user connection may be less expensive than the use of a normal cellular radio network. However, when the user is beyond the coverage area of his autonomous de- 35 vice he may use his subscriber terminal as a terminal of a normal cellular radio network. The described solution offers many advantages: the user acquires the desired service as inexpensively as possible and needs only one subscriber terminal. However, the described solution has one major problem that the DECT system does not have. The autonomous device must operate at the same frequencies as the subscriber terminal. This causes interference in the radio connections between base stations and subscriber terminals in the area. The radio connection that the autonomous device uses can also be interfered with. If the autonomous device is allowed to operate at the whole spectrum of a known cellular radio network, the interference can be characterized as sto- chastic. This makes it very difficult or even impossible to design a good cellular radio network. SUMMARY OF THE INVENTION The object of the present invention is to provide a method that solves the problems of prior art solutions. This is achieved with the method set forth in the preamble, which is characterized in that the autonomous device is directed to use certain parts of the spectrum of at least one cellular radio network when selecting the frequency. The invention also relates to an autonomous device operating at the spectrum of at least one cellular radio network and having a bi-directional radio connection to the subscriber terminal and selecting automatically and dynamically the frequency to be used on the bi-directional radio connection. The device is characterized in that it comprises control means for directing the autonomous device to use certain parts of the spectrum of at least one cellular radio network when selecting the frequency. Great advantages are achieved with the method of the invention, the most important advantage being the elimination of interference. The autonomous device then operates without interference and does not cause interference to the radio connections between base stations and subscriber terminals audible in the area. Another important advantage is that the autonomous devices are not dependent on operators; only after performing the control function described in the method do they operate in the network of a certain operator. The device of the invention has the same advantages that have above been described for the method. The preferred embodiments of the in- vention and other more detailed implementations emphasize the advantages of the invention. BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention will be described in greater detail with reference to examples in the accompanying drawings, in which Figure 1 shows the autonomous devices described above, Figure 2 shows the spectrum of a cellular radio network, Figure 3 shows how carrier waves are positioned at the spectrum of a cellular radio network, Figure 4 shows the operating principles of the method, Figure 5 shows the parts of the autonomous device that are essential to the invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Figure 2 illustrates as an example the spectrum of a GSM cellular radio network. The spectrum is located between 890 and 960 MHz. The uplink uses the frequency range from 890 to 915 MHz 200 and the downlink uses the frequency range from 935 to 960 MHz 202. In practice it should be noted that a certain operator has access to only a certain part of the entire spectrum. Figure 3 shows how the carrier waves are positioned at the spectrum of the GSM cellular radio network. The carrier wave space is 200 KHz. The Figure shows some of the first carrier waves 300, 302, 304, 306, 308, 310, 312 of the ascending transmission direction. Usually a base station com- prises one or two transceivers per each sector of a cell. The transport capacity of one carrier wave is eight traffic channels. Figure 4 illustrates the operating principles of the method. The home repeater 110 has a bi-directional radio connection (ascending transmission direction 902,2 MHz and descending transmission direction 947,2 MHz) 160 with the base station 100 of the cell 420 in the area. Furthermore the cells 400 (ascending transmission direction 890,2 MHz and descending transmission direction 935,2 MHz), 402 (ascending transmission direction 892,2 MHz and descending transmission direction 937,2 MHz), 404 (ascending transmission direction 894,2 MHz and descending transmission direction 939,2 MHz), 406 (ascending transmission direction 896,2 MHz and descending transmission direction 941 ,2 MHz), 408 (ascending transmission direction 898,2 MHz and descending transmission direction 943,2 MHz), 410 (ascending transmission direction 900,2 MHz and descending transmission direction 945,2 MHz) are audible in the area. The home repeater 110 automatically and dynamically selects the frequency to be used in a bi-directional radio connection 170. In this method the home repeater 110 is directed to use certain parts 210, 220 of the spectrum 200, 202 of at least one cellular radio network when selecting the frequency. According to the Figure 2 the home repeater 110 is directed to search for the carrier frequency which is best audible to the subscriber terminal 140 for its bi-directional radio connection 170 within the limits ranging from 910 to 914 MHz for the ascending transmission direction and ranging from 950 to 954 MHz for the descending transmission direction. Possible interference is thus minimized as the autonomous device 110, 130 is able to search for the frequencies it uses only in such a part 210, 220 of the spectrum 200, 202 of the cellular radio network that is not in use in the coverage area of the autonomous device 110. Certain parts of the spectrum are defined by giving each part 210, 220 of the spectrum a lower limit 212, 222 and an upper limit 214, 224. Figure 1 shows that the control is carried out by means of remote control; control information is transmitted from the base station 100 or from a part of the public telephone network 120 to the autonomous device 110, 130 using either bi-directional radio connections 160 or a cable 162. The remote control 160, 162 is carried out in real time. In bi-directional radio connections 160 the remote control is carried out by means of the air interface. An authentication procedure is used to check that the remote control 160, 162 is permis- sible. The authentication complies with prior art and is consequently not described in detail here. The information received by the remote control 160, 162 is recorded in the memory 550 of the autonomous device 110, 130. Another way to carry out the control is to program the memory 550 of the autonomous device 110, 130 before it is taken into use. The memory 550 of the autonomous device 110, 130 is arranged in a separate device, for instance in a SIM card. The operator or the vendor sets into the memory the frequency range limits 212, 214, 222, 224 that the autonomous device can use when searching for the frequency to be used for its bi-directional radio connection 170, 172 in the subscriber terminal 140, 142. Figure 5 shows the parts of the autonomous device 110, 130 that are essential to the invention. In operation, the autonomous device 110, 130 uses the control method described above. The autonomous device comprises an antenna 500, a duplex filter 510, a receiver 530, a transmitter 520, a user interface 560 and control means 540 to direct the autonomous device 110, 130 to use certain parts 210, 220 of a spectrum 200, 202 of at least one cel- lular radio network when selecting the frequency. The control is carried out in such a way that the control means 540 are adapted to receive remote control 160, 162. In addition, the autonomous device 110, 130 comprises memory means 550 for storing the information received by remote control 160, 162. Before the device is taken into use, these memory means 550 may be pro- grammed in order to carry out the control. An example of the memory means 550 is the SIM card. The simplest way to implement the invention is that the steps of the method of the invention, which are carried out in the means described above, can be converted into executable software. The software is then stored in the memory means 550 and carried out in the control means 540, the software thus controlling the operation of the means 500, 510, 520, 530, 550 and 560. The means required by the method of the invention may also be implemented by means of general or signal processors or separate logic. Even though the invention has been explained in the above with reference to examples in accordance with the accompanying drawings, it is obvious that the invention is not restricted to them but can be modified in a variety of ways within the scope of the inventive idea disclosed in the above and in the attached claims.

Claims: CLAIMS 1. A method of controlling an autonomous device (110, 130), which autonomous device (110, 130) operates at a spectrum of at least one cellular radio network (200, 202), and which autonomous device (110, 130) has a bi- directional radio connection (170, 172) to a subscriber terminal, and which autonomous device (110, 130) automatically and dynamically selects the frequency to be used in the bi-directional radio connection (170, 172), characterized in that the autonomous device (110, 130) is directed to use certain parts (210, 220) of the spectrum (200, 202) of at least one cellular ra- dio network when selecting the frequency. 2. A method as claimed in claim 1, characterized in that the control is implemented by means of remote control (160, 162). 3. A method as claimed in claim 2, characterized in that the remote control (160, 162) is carried out in real time. 4. A method as claimed in claim 3, characterized in that the remote control is implemented by means of the air interface (160). 5. A method as claimed in claim 2, characterized in that the authorization of the remote control (160, 162) is checked by an authentication method. 6. A method as claimed in claim 2, characterized in that the information received by the remote control (160, 162) is stored in the memory (550) of the autonomous device (110, 130). 7. A method as claimed in claim 1, characterized in that certain parts of the spectrum (210) are determined by giving each part (210, 220) of the spectrum a lower limit (212, 222) and an upper limit (214, 224). 8. A method as claimed in claim 1, characterized in that the control is carried out by programming the memory (550) of the autonomous device (110, 130) before it is taken into use. 9. A method as claimed in claims 6 and 8, characterized in that the memory (550) of the autonomous device (110, 130) is arranged in a separate device. 10. A method as claimed in claim 9, characterized in that the separate device is a SIM card. 11. A method as claimed in claim 1, characterized in that the autonomous device is a home base station (130). 12. A method as claimed in claim 1, characterized in that the autonomous device is a home repeater (110). 13. An autonomous device (110, 130) which operates at the spectrum (200, 202) of at least one cellular radio network and has a bi-directional radio connection (170, 172) to a subscriber terminal, and which automatically and dynamically selects the frequency to be used in the bi-directional radio connections (170, 172), characterized in that the autonomous device (110, 130) comprises control means (540) for directing the autonomous device (110, 130) to use certain parts (210, 220) of the spectrum (200, 202) of at least one cellular radio network when selecting the frequency. 14. A device as claimed in claim 13, c h a ra cte ri ze d in that the control means (540) are adapted to receive remote control (160, 162). 15. A device as claimed in claim 14, characterized in that the autonomous device (110, 130) comprises memory means (550) for storing the information received by the remote control (160, 162). 16. A device as claimed in claim 13, characterized in that the autonomous device (110, 130) comprises memory means (550) that are programmed for implementing the control before the device is taken into use. 17. A device as claimed in claim 15 or 16, characterized in that the memory means (550) is a SIM card. 18. A device as claimed in claim 13, characterized in that the autonomous device is a home base station (130). 19. A device as claimed in claim 13, characterized in that the autonomous device is a home repeater (110).

Inventors: MAENNISTOE HARRI, MAENNISTOE, HARRI
Applicants: MAENNISTOE HARRI, NOKIA TELECOMMUNICATIONS OY, MAENNISTOE, HARRI
Application year: 1997
Main classification: H04Q7
IPC codes: H04B7, H04W16