Method of allocating radio channels

• US 5,625,878 A
• Filed: 02/28/1996
• Issued: 04/29/1997
• Est. Priority Date: 11/11/1991
• Status: Expired due to Fees

• Current Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Original Assignee: Nokia Telecommunications Oy (Nokia Corporation)
• Inventors: Rautiola, Markku, Lopponen, Jussi
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Nguyen, Lee
• Application Number:
  US08/608,034
• Time in Patent Office: 426 Days
• Field of Search: 455/34.1, 455/34.2, 455/53.1, 455/54.1, 455/54.2, 455/56.1, 455/33.1, 455/33.2, 455/32.1, 379/58, 379/59, 379/60, 379/63
• US Class Current: 455/509
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 4/06 Selective distribution of broadcast services, e.g. multimedia broadcast multicast service [MBMS]; Services to user groups; One-way selective calling services
• CPC Class Codes: H04W 48/08 Access restriction or access information delivery, e.g. discovery data delivery signalling during connection H04W76/00
• CPC Class Codes: H04W 48/16 Discovering, processing access restriction or access information

Abstract

A channel allocation method in a cellular radio system. The mobile radios have permanently stored in their memories a first group of radio channels scanned in a normal hunt sequence and a second group of radio channels scanned in a comprehensive hunt sequence. When the control channel of a base station is changed, a channel permanently belonging to the first group is allocated as a new control channel to the base station whenever such a channel is available. If a channel belonging to the second group has to be allocated as a control channel, it is transferred temporarily to the first group and the change of group is announced through control channels to the mobile radios. A channel permanently belonging to the first group is re-established as the control channel of a base station as soon as such a channel is available and the freed channel is returned to the second group.

Claims

1. A method of allocating radio channels in a radio system, comprising mobile radio stations and several fixed radio stations located separate from one another within a geographical area covered by the radio system, traffic channels and one control channel being allocated to each fixed radio station, and each mobile station having, permanently stored in its memory, a first group of channels of the radio system assigned primarily as control channels, the mobile station searching for a control channel in the first group in a normal hunt sequence, and each mobile station further having, temporarily stored in its memory and updated through control channels by the fixed radio stations, a second group of radio channels assigned primarily as traffic channels but also useable as control channels, the mobile station searching for a control channel in the second group in a comprehensive hunt sequence if the normal hunt sequence is unsuccessful, in which method changing of a control channel of a fixed station comprises the steps of:

a) allocating a radio channel permanently belonging to the first group as a new control channel to the fixed base station whenever such a channel is available,

b) allocating a radio channel belonging to the second group as a new control channel if a radio channel permanently belonging to the first group is not available, transferring said radio channel belonging to the second group temporarily to the first group and announcing the change of group through control channels to the mobile stations,

c) assigning a radio channel permanently belonging to the first group, as a control channel of the fixed radio station as soon as it becomes available, and

d) returning a radio channel temporarily transferred to the first group back to the second group, when said channel is freed from use as a control channel, and announcing the change of group through control channels to the mobile station;

the radio channels assigned only as traffic channels being in third and fourth groups of radio channels, and selection of traffic channels for a call comprises the steps of;

e) making a first search for a traffic channel among the channels belonging to the third group,

f) making a further search for a traffic channel among the channels belonging to the second group, if there are no free channels available in the third group,

g) making a still further search for a traffic channel among the channels belonging to the first group, if there are no free channels available in the second group, and

h) making a still further search for a traffic channel among the channels belonging to the fourth group, if there are no free channels available in the first group.

2. A method for allocating radio channels in a radio system which includes a plurality of mobile radio stations, a plurality of fixed radio stations located within a geographical area covered by the radio system, each fixed radio station having a plurality of channel units each comprising a radio transceiver for transmitting and receiving on a radio channel, a mobile exchange having a call control computer and a plurality of interface units each operating as a link between the call control computer and a respective channel unit of a respective fixed radio station, the call control computer being capable of allocating free radio channels, channel units and interface units for each call in which at least one mobile radio station of the radio system participates, said method comprising:

(a) allocating radio channels potentially available for use by said transceivers for communicating with said mobile radio stations, into;

(i) a smaller, first group which, when used, are to be used as control channels reserved for signalling between a fixed radio station and a mobile radio station for at least one of call set up, registration of a mobile radio station to a fixed radio station, transmission of a status message and broadcasting of network information to mobile radio stations, and for signalling by a mobile radio station back to the mobile exchange via a fixed radio station upon receiving a control signal via a fixed radio station, but normally for receiving or transmitting by a mobile radio station while a call involving such mobile radio station is in progress, and

(ii) a larger, second group which, when used, are to be used, unless temporarily co-opted, as traffic channels for passing communications traffic to and from the mobile radio stations within calls;

(b) providing each mobile radio station with a nonvolatile memory storing a channel table listing all of said allocated radio channels including a default listing of which of said radio channels are in said first group and which of said radio channels are in said second group, and a volatile memory into which said channel table, including said default listing, is read when the respective mobile radio station is turned on;

(c) monitoring by said mobile exchange of the number and distribution of radio channels currently useable as control channels currently allocated to said first group;

(d) as a result of said monitoring, when said radio channels currently useable as control channels currently allocated to said first group drop to a low value which is below a threshold value absolutely or geographically, temporarily reallocating one or more radio channels from said second group to said first group, and signalling to said fixed radio stations for transmission thereby to said mobile radio stations control signals which upon reception by said mobile radio stations alter said channel table as existing in the volatile memory of each mobile radio station when turned on, to correspondingly revise said listing of which of said radio channels are currently in said first group and which of said radio channels are currently in said second group;

(e) as a result of said monitoring, when said radio channels currently useable as control channels currently allocated to said first group and contained in said default listing after step (d) has been conducted raise to a higher value than said low value, absolutely or geographically, immediately reallocating to said second group one or more of the radio channels which were temporarily allocated from the second group to the first group in step (d), and signalling to said fixed radio stations for transmission thereby to said mobile radio stations control signals which upon reception by said mobile radio stations alter said channel table as existing in the volatile memory of each mobile radio station when turned on, to correspondingly revise said listing of which of said radio channels are currently in said first group and which of said radio channels are currently in said second group;

(f) upon each such revision allocating a respective at least one radio channel presently in the first group to each said fixed radio station for use as a respective control channel;

(g) each said mobile radio station, when in a turned on status and at a loss for but in need of an effective control channel communicating relationship with a fixed radio station attempting to perform at least one of;

(i) a resuming control channel sequence, in which the mobile radio station returns to the control channel it was listening to most immediately previously;

(ii) a single hunt sequence, in which the mobile radio station takes up a particular control channel as commanded by the mobile exchange;

(iii) a preferential hunt sequence, in which the mobile radio station scans for control channels as stored in a data table of adjacent ones of said fixed radio stations and selects therefrom one control channel having a field strength which is stronger than a threshold value of field strength; and

(h) when, after conducting step (g) a mobile radio station, when in a turned on status remains at a loss for but is in need of an effective control channel communicating relationship with a fixed radio station, performing a normal hunt sequence, in which the radio channels currently carried in the listing in the volatile memory of the respective mobile radio station as being in the first group are scanned, and one of them, being free, is selected by the mobile radio station as an effective control channel.