Method of covering shadow areas in a cellular mobile radio system and radio booster for implementing this method
First Claim
1. A method of ensuring service to shadow areas in a cellular mobile radio system comprising a plurality of cells each covered by a base transceiver station adapted to transmit and to receive radio signals to and from mobile stations in an associated cell on different frequencies, at least one of said shadow areas being in one of said cells, a radio booster being associated with each of said shadow areas to receive, amplify and retransmit said radio signals to and from mobile stations in said shadow area, said radio booster being adapted to cover a given shadow area being subordinate to said base transceiver station of said associated cell in which said shadow area is located, said method comprising the steps of:
- establishing a radio connection between (1) a base transceiver station in a cell having an associated shadow area and a radio booster, and (2) one of said mobile stations located in said associated shadow area, said establishing step comprising the steps of;
transmitting, from said mobile station to said radio booster, an access request radio signal on a predetermined access channel conveyed by an upward translated control frequency;
modifying, at said radio booster, said access request radio signal to include information indicating that said mobile station is in a shadow area, to obtain a modified access request radio signal;
retransmitting said modified access request radio signal from said radio booster to a base station controller within said base transceiver station on an upward control frequency different from said upward translated control frequency;
assigning, at said base station controller, a traffic channel conveyed by at least one translated traffic frequency to said mobile station which said mobile station must use to communicate with said radio booster, said assigning step comprising the steps of;
determining, by said base transceiver station, on receiving said modified access request radio signal, that said mobile station is in said associated shadow area and that a frequency translation law has to be used, said frequency translation law associating translated traffic frequencies to respective traffic frequencies; and
deducing from at least one traffic frequency which is selected by said base transceiver station to communicate with said radio booster for establishing said radio connection and from said frequency translation law at least one translated traffic frequency which has to be used by said mobile station to communicate with said radio booster for establishing said radio connection;
transmitting, from said base transceiver station to said radio booster on a downward control frequency, a signal adapted to advise said mobile station that it must use said at least one translated traffic frequency for establishing said radio connection; and
retransmitting, from said radio booster to said mobile station said signal on a downward translated control frequency.
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Accused Products
Abstract
A mobile radio network comprises a base transceiver station for transmitting and receiving radio signals to and from mobiles on different basic frequencies and a radio booster for receiving, amplifying and retransmitting radio signals to and from at least one shadow area. To cover the shadow areas a radio signal received by a radio booster from the base transceiver station on a basic frequency is retransmitted to a mobile station on a translated frequency different from the basic frequency and associated with the latter by a translation law. This law is such that, firstly, each of the basic frequencies is either associated with at least one translated frequency or is not associated with any translated frequency and, secondly, the difference between the value of a translated frequency and the value of the associated basic frequency is not the same for all the translated frequencies. A radio signal received by a radio booster from a mobile on a translated frequency is retransmitted to the base transceiver station on the associated basic frequency.
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Citations
17 Claims
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1. A method of ensuring service to shadow areas in a cellular mobile radio system comprising a plurality of cells each covered by a base transceiver station adapted to transmit and to receive radio signals to and from mobile stations in an associated cell on different frequencies, at least one of said shadow areas being in one of said cells, a radio booster being associated with each of said shadow areas to receive, amplify and retransmit said radio signals to and from mobile stations in said shadow area, said radio booster being adapted to cover a given shadow area being subordinate to said base transceiver station of said associated cell in which said shadow area is located, said method comprising the steps of:
establishing a radio connection between (1) a base transceiver station in a cell having an associated shadow area and a radio booster, and (2) one of said mobile stations located in said associated shadow area, said establishing step comprising the steps of; transmitting, from said mobile station to said radio booster, an access request radio signal on a predetermined access channel conveyed by an upward translated control frequency; modifying, at said radio booster, said access request radio signal to include information indicating that said mobile station is in a shadow area, to obtain a modified access request radio signal; retransmitting said modified access request radio signal from said radio booster to a base station controller within said base transceiver station on an upward control frequency different from said upward translated control frequency; assigning, at said base station controller, a traffic channel conveyed by at least one translated traffic frequency to said mobile station which said mobile station must use to communicate with said radio booster, said assigning step comprising the steps of; determining, by said base transceiver station, on receiving said modified access request radio signal, that said mobile station is in said associated shadow area and that a frequency translation law has to be used, said frequency translation law associating translated traffic frequencies to respective traffic frequencies; and deducing from at least one traffic frequency which is selected by said base transceiver station to communicate with said radio booster for establishing said radio connection and from said frequency translation law at least one translated traffic frequency which has to be used by said mobile station to communicate with said radio booster for establishing said radio connection; transmitting, from said base transceiver station to said radio booster on a downward control frequency, a signal adapted to advise said mobile station that it must use said at least one translated traffic frequency for establishing said radio connection; and retransmitting, from said radio booster to said mobile station said signal on a downward translated control frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A radio booster in a mobile radio system comprising a plurality of cells, for ensuring radiocommunications in a shadow area included in a cell covered by a transceiver station cell, said radio booster comprising:
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means for modifying an access request radio signal received on an upward translated control frequency from a mobile station belonging to said shadow area, to include information indicating that said mobile station is in a shadow area, to obtain a modified access request radio signal, said access request radio signal being sent by said mobile station for establishing a radio connection; means for retransmitting said modified access request radio signal to said base transceiver station on an upward control frequency different from said upward translated control frequency, thereby informing said base transceiver station that said mobile station is in said shadow area and that a frequency translation law has to be used for deducing a translated traffic frequency which has to be used by said mobile station to communicate with said radio booster from a traffic frequency which is selected by said base transceiver station to communicate with said radio booster when establishing said radio connection with said mobile station.
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Specification