Title of Invention

A WIRELESS COMMUNICATION SYSTEM

Abstract

A WIRELESS COMMUNICATION SYSTEM A destination station in a wireless communication system for a multi-hop connection selects a transmission path having a minimum total of required transmission power values of respective stations on the transmission path among candidates of the transmission path from a source station to the destination station and transmits a pilot signal to the source station and a relay station, the pilot signal comprising identification information about the respective stations on the selected transmission path and required transmission power values thereof. Thus, the source station and the relay station, which have rece3ived this pilot signal, can determine the transmission path having the minimum total of the required transmission power values by use of the identification information included in the received pilot signal.

Full Text

WIRELESS COMMUNICATION SYSTEM FOR MULTI-HOP CONNECTION. SOURCE STATION. RADIO STATION AND PILOT SIGNAL USED THEREIN power make it impossible to establish the wireless link between the source station and the destination station, thereby resulting in lowering of an area The relay station specifies the transmission path from the source transmission path having a minimum total of the transmission power values among candidates of the specified transrisaction path, generates wireless communication system for a multi-hop connective according to one embodiment. station 1 to the destination station 3 and a transmission path in which the signal is transmitted by being relayed through one or more of the relay stations 2 before reaching the destination station 3 from the source station 1. the destination station 3. FIG. 7 IS a tlowchart showing one example of a proecessing in the relay station 2 in the case of directly receiving the path signal from the source station 1 (a second hop). Meanwhile, in Step 26 immediately after Step 21 the comparison sub-unit 26 determines whether or not another pilot and has been already tranmission power value that satisfies a desired SIR in the immediately preceding relay station 2 by use of at least one of the measured received SIR. a desired received SIR and the transmission power value of the immediately preceding relay station 2. In Step 33, the total calculation sub-unit Gl of the required transmission power total calculation unit 34 adds up all of required transmission power values included m the received pilot signal and the required transmission power value calculated for the pilot signal by the power value calculation sub-unit thus calculating a total of the required transmission power values of the respective stations on the transmission path of the pilot signal In Step 34, the comparison sub-unit 36 compares the total of the required ti-ansmission power values, which is calculated for the pilot signal by the required transmission power total calculation unit 34, to a total of the required transmission power values stored in the storage sub-unit 35. If the calculated total of the required transminsion power values is smaller than the stored total, the processing advances to Step 35, and if not, the processing returns to Step 31. In Step 35; having found out that the transmission path of the pilot siganal is a transmission path having a minimum total of the required transmission power values, the comparison sub-unit 36 updates the identification information and required transmission power values stored in the st;orage sub-umt 35 by use of all of the identification information and required transmission power values included in the pilot signal and the required transmission power value calculated for the immediately preceding relay station, from which the pilot signal is transmitted, by the power value calculation sub-unit 60. Specifically, by use of the identification information and required transmission power values for the respective stations on the transmission path of the pilot signal, the information stored in the storage sub-unit 35 is updated. After the above-described updating, the processing returns to Step 31 and the foregoing processing is repeated. Meanwhile, in Step 36 immediately after Step 31, the com[arison sub-unit 36 determines whether or not another pilot signal has been already received. If no pilot signal ha- been received, the processing advances to Step 37 and a buil in timer is started. In other words, the built-in timer is started by taking the first time of receiving a pilot signal as a trigger. In Step 38, by use of the builfin timer, the comparison sub-unit 36 determines whether or not a fixed period of time has passed. Up until the fixed period of time elapses, the above-described processing from Step 31 to Step 35 IS repeated, and the processing advances to Step 39 as the fixed period of time elapsed. In such a manner, among the candidates of the transmission path from the source station 1 to the destination station 3, a transmission path havmg a mmimum total of required transmission power value; at the elapse of the fixed period of time is selected, thus resulting m a state where the identification information and required transmission power values for all the stations on the transmission path are stored in the storage sub unit 35. In Step 39, the pilot signal -generation unit 3S reads out the information stored m the storage sub-unit 35, that is, the identification information and required transmission power values for all the stations on the transmission path having the minimum total of the required transmission power values. and generates a pilot signal by making these information into frames. In Step 40, the transmission unit 39 transmits the generated pilot signal. The pilot signal thus transmitted is received by the source station 1 and the respective relay stations 2. This pilot signal may be received by the source station 1 after going through any of the relay stations 2 or may be received directly from the destination station 3. Thereafter the source station 1 and the respective relay stations 2 determine the transmisssion path having the minimum total of the required transmission power values by use of the identification information included m the received pilot signal and transunits the signal by use of the transmission power prescribed by the required transmission power value included in the received pilot signal. Therefore, according to the embodiment, the destination station 3 selects the transmission path having the minimum total of the required transmission power values of the respective stations on the transmission path among the candidates of the transmission path from the source station 1 to the destination station 3 and transmits the pilot signal to the source station 1 and the relay station 2, the pilot signal including the identification information about the respective stations on the selected transmission path and the required transmission power values thereof Thus, in transmitting signals thereafter, the source station 1 and the relay station 2, which have received this pilot signal, can determine the transmission path having the minimum total of the required transmission power values by use of the identification information included in the received pilot signal and can also transmit the signal at the transmission power prescribed by the required transmission power value included in the received pilot signal. In such a manner, the total of the required transmission power values in transmitting the signal from the source station 1 to the destination station 3 can be minimized, the increase of the interference noise generated in relaying of the signal transmission by the relay station 2 can be suppressed, and the increase of the system capacity and the area coverage can be achieved. Note that, in the embodiment, the power value calculation sub-unit 50 of the required transmission power total calculation unit 24 in the relay station 2 and the power value calculation sub-unit GO of the required transmission power total calculation unit 34 in the destination station 3 calculate the required transmission power value in the immediately preceding station, from which the pilot signal is transmitted, by use of the transmission power values included in the received pilot signal, respectively. However, there is no limitation placed in this regard. As another embodiment, storage units that store transmission power values in other stations may be provided in the relay station 2 and the destination station 3, and in calculating a required transmission power value m a immediately preceding station, the transmission power values stored m the storage units may be used. Moreover, though the relay station 2 in the embodiment has the constitution shown in FIG. 6, a constitution shown m FIG. 14 may be also adopted. The relay station 2 shown in FIG. 14 has a constitution using a selection unit 43 that has a storage sub-unit 25, a comparison sub-unit 41 and a switch 42, instead of the selection unit 27 of FIG. 6. Note that the other constituent components that are the same as those of FIG. 6 are denoted by the same reference numerals. In the Constitution shown m FIG. 14, the pilot signal generation unit 28 generates a pilot signal by making into frames the following: all the identification information and required transmission power values included in the received pilot signal; the required transmission power value calculated by the power value calculation sub-unit 50 of the required transmission power total calculation unit 24; and the identification information about the relay station and the transmission power value thereof. The comparison sub-uni: 41 compares the total of the required transmission power values calculated for the received pilot signal by of the required transmission power total calculation unic 24 to the total of the required transmission power values stored m the .storage sub-unit 25, updates the identification information and required transmission power values stored in the storage sub-unit 25 by use of the identification inforraation and required transmission power values for the respective stations, which are included in the pilot signal, and the required transmission power value calculated by the power value calculation sub-unit 50 only if the calculated total of the required transmission power values is smaller than the stored total and transmits the pilot signal generated by the pilot signal generation unit 28 to the transmission unit 29 by turning on the switch 42. Unlike the relay station of FIG. G, the relay station 2 of FIG. 14 is not the one selecting the transmission path having the minimum total of the required transmission power values when receiving the pilot signal m the fixed period of time. However, by transmitting the pilot signal as described above, the destination station 3 can provide information for selecting the transmission path having the minimum total of the required transmission power values. Moreover, by successively processing the pilot signal at each time of the reception thereof, a transmission delay of the pilot signal can be reduced. Moreover, the wireless communication system according to the embodiment can be applied to incoming and outgoing links of a cellular communication system such as TDMA, CSMA, CDMA and the like. For example, in the case of the application thereof to the outgoing link, the source station 1 corresponds to a base station, the destination station 3 corresponds to a mobile station, and the relay station 2 corresponds to a mobiles, station or a station dedicated to relay. In the case of the application thereof to the incoming link, the source station 1 corresponds to the mobile station and the destination station 3 corresponds to the base station. Moreover, in the embodiment, the pilot signal is transmitted including the identification information of the respective stations, the required transmission power values thereof and the like. However, a signal including control information besides the above information may be used as the pilot signal. WE CLAIM 1. A wireless communication system for a multi-hop connection, which performs signal transmission between a source station, plurality of relay stations and a destination station, the source station comprising: a transmission unit configured to transmit a pilot signal including identification information of the source station, the relay station compnsing- a reception unit configured to receive a pilot signal; a required transmission power total calculation unit configured to specify a transmission path from the source station to the relay station by use of information included in the received pilot signal and calculate a total of required transmission power values of respective stations on the transmission path; a selection unit configured to select a transmission path having a minimum total of the required transmission power values among candidates of the specified transmission pathi and a transmission unit configured to transmit a pilot signal including identification information about respective stations on the selected transmission path and required transmission power values thereof; and the destination station comprising^ a reception unit configured to receive a pilot signal; a required transmission power total calculation unit configured to specify a transmission path from the source station to the destination station by use of information included in the received pilot signal and calculate a total of required transmission power values of respective stations on the transmission path; a selection unit configured to select a transmission path having a minimum total of the required transmission power values among candidates of the specified transmission path: and a transmission unit configured to transmit a pilot signal including identification information about respective stations on the selected transmission path and required transmission power values thereof. 2. The wireless communication system for a multi-hop connection of Claim 1, wherein the transmission units transmit a pilot signal at a transmission power prescribed in respective transmission power values, respectively, the reception units have a received SIR measurement unit configured to measure a received SIR obtained when receiving the pilot signal, the required transmission power total calculation units have a power value calculation sub-unit configured to calculate a required transmission power value in an immediately preceding station, from which the pilot signal is transmitted, by use of at least one of a transmission power value of the immediately preceding station, the measured received SIR and a desired received SIR, and a total calculation sub-unit configured to calculate a total of required transmission power values of respective stations on the transmission path by use of required transmission power values included in a received pilot signal and t.ae required transmission power value calculated for the pilot signal by the power value calculation subunit. 3. The wireless communication system for a multi-hop connection of Claims 1 or 2, wherein the reception units receive a pilot signal for a fixed period of time, the selection units select a transmission path having a minimum total of required transmission power values among candidates of the transmission path for the pilot signal received m this fixed period of time, 4. A source station performing signal transmission with at least one of a relay station and a destination station, the source station comprising: a pilot signal generation unit config:ured to generate a pilot signal including identification information and transmission power values of the source station; and a transmission unit configured to transmit the pilot signal by use of a power prescribed in the transmission power values. 5. A radio station performing signal transmission with at least one of a source station, a relay station and a destination station, the radio station comprising: a reception unit configured to receive a pilot signal; a required transmission power total calculation unit configured to specify a transmission path from the source station to the relay station by use of information included in the received pilot signal and calculate a total of required transmission power values of respective stations on the transmission path; a selection unit configured to select a transmission path having a minimum total of the required transmission power values among candidates of the specified transmission path; and a transmission unit configured to transmit a pilot signal including identification information about respective stations on the selected transmission path and required transmission power values thereof, 6. The radio station of Claim 5, further comprising a received SIR measurement unit configured to measure a received SIR obtianed when receiving the pilot signal, the transmission unit transmits a pilot signal at a transmission power prescribed in a transmission power value, the required transmission power total calculation unit has a power value calculation sub-unit configured to calculate a required transmission power value in an immediately preceding station, from which the pilot signal is transmitted, by use of at least one of a transmission power value of the immediately preceding station, the measured received SIR and a desired received SIR and a total calculation sub-unit configured to calculate a total of required transmission power values of respective stations on the transmission path by use of required transmission power values included in a received pilot signal and the required transmission power value calculated for the pilot signal by the power value calculation sub-unit. 7. The radio station of Claim 6, wherein the power value calculation sub-unit uses a transmission power value included in the received pilot signal. 8. The radio station of Claim 7, wherein the transmission unit transmits a pilot signal including a transmission power value of the radio station. 9. The radio station of Claim 6, wherein the power calculation sub-unit uses previously stored transmission power values for other stations. 10. The radio station of Claim 5, wherein the selection unit has a storage sub-unit configured to store identification information and required transmission power values and a comparison sub-unit configured to compare a total of required transmission power values calculated for a received pilot signal by the required transmission power total calculation unit of the relay station to a total of the required transmission power values stored in the storage sub'unit, and if the total of the required transmission power values calculated for the pilot signal is smaller, update the identification infoixiation and the required transmission power values, which are stored in the storage sub-unit, by use of identification information about respective stations on a transmission path of the pilot signal and required transmission power values thereof 11. The radio station of any one of Claims 5 to 10, wherein the reception unit receives a pilot signal for a fixed period of time and the selection unit selects a transmission path having a minimum total of required transmission power values among candidates of the transmission path for the pilot signal received in this fixed period of lime. 12. A pilot signal used in a wireless communication system for a multi-hop connection, the system performing signal transmission between a source station, a plurality of relay stations and a destination station, the pilot signal comprising: identification information about the respective stations on the transmission path of the pilot signal and required transmission power values thereof in order to enable selection of a transmission path having a minimum total of required transmission power values of respective stations. 13. A wireless communication method for a multi-hop connection, which performs signal transmission between a source station, plurality of relay stations and a destination station, when receiving the pilot signal from the source station directly, the relay station measures a received SIR of the pilot signal, calculates a required transmission power value of the source station by use of at least one of a transmission power value of the source station, the measured received SIR and a desired received SIR, generates a pilot signal including identilication information and the required transmisson power values of the source station, and transmits the pilot signal by use of a power prescribed in the transmission power values of the relay station. 14. A wireless communication method for a multi-hop connection, which performs signal transmission between a source station, plurality of relay stations and a destination station, when receiving the pilot signal from the other relay station, the relay station measures a received SIR of the pilot signal, calculates a required transmission power value of the source station by use of at least a transmission power value of the source station,the measured received SIR and a desired received SIR, specifies a transmission path from the source station to the relay station by use of information included in the received pilot signal, calculates a total of required transmission power values of respective stations on the transmission path by use of required transmission power values included in a received pilot signal and the required transmission power value calculated for the pilot signal, selects a transmission path having a minimum total of the required transmission power values among candidates of the specified transmission path, generates a pilot signal including identification information and the required transmission power values of the source station, and transmits the pilot signal by use of a power prescribed in the transmission power values of the relay station. 15. A wireless communication method for a multi-hop connection, which performs signal transmission between a source station, plurality of relay stations and a destination station, the destination station - measures a received SIR of the pilot signal, calculates a required transmission power value in an immediately preceding station, from which the pilot signal is transmitted, by use of a transmission power value of the immediately preceding station, at least one of the measured received SIR and a desired received SIR, specifies a transmission path from the source station to the destination station by use of information included in the received pilot signal. calculates a total of required transmission power values of respective stations on the transmission path by use of required transmission power values included in a received pilot signal and the required transmission power value calculated for the pilot signal. selects a transmission path having a minimum total of the required transmission power values among candidates of the specified transmission path. transmits a pilot signal including identification information about respective stations on the selected transmission path and required transmission power values thereof. 16. A wireless communication system, substantially as hereinabove described and illustrated with reference to the accompanying drawings. Dated this 28 day of February 2003 (MVG MENON) OF DePENNING & DePENNING AGENT FOR THE APPLICANTS

Documents:

159-che-2003-abstract.pdf

159-che-2003-claims.pdf

159-che-2003-correspondenc others.pdf

159-che-2003-description complete.pdf

159-che-2003-drawings.pdf

159-che-2003-form 1.pdf

159-che-2003-form 3.pdf