Method and arrangement in an analogue mobile telesystem

• US 5,875,399 A
• Filed: 12/20/1996
• Issued: 02/23/1999
• Est. Priority Date: 06/27/1994
• Status: Expired due to Fees

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Hayes, John, Laurendeau, Francine, Hamill-Keays, Anneli, Kallin, Harald
• Primary Examiner(s): LE, THANH C
• Application Number:
  US08/750,873
• Time in Patent Office: 795 Days
• Field of Search: 455/422, 455/432, 455/433, 455/434, 455/435, 455/450, 455/451, 455/452, 455/455, 455/507, 455/509, 455/511, 455/515, 455/62, 455/63, 455/65, 455/67.1, 455/161.1 , 455/161.2, 455/161.3, 455/226.1
• US Class Current: 455/434
• CPC Class Codes: H04W 48/20 Selecting an access point

Abstract

An analogue mobile telesystem has traffic channel cells (C1), each of which includes a base station (A-G). These base stations handle combined control channels (PAC) for paging a mobile station (MS), and also access channels (AC) for establishing connections to or from the mobile station (MS). The mobile station has information concerning the frequencies of all of the access channels and the connections are established on duplex traffic channels (TC). The geographical area covered by respective traffic channel cells (C1) is determined by virtue of enabling all traffic channels (TC) within this area to be used for predetermined, common purposes. Each of the traffic channel cells (C1) has at least two access channels (PAC, AC) spaced apart at a desired frequency distance and having the same radio coverage as the traffic channels (TC). When desiring access, the mobile station (MS) scans the strength or power of all access channels on two separate occasions at a mutual spacing of 20 milliseconds. The duplex access channels (PAC, AC) assist the mobile station (MS) in finding the strongest access channel (PAC, AC) despite heavy fading. The mobile station (MS) thereby establishes a connection on the traffic channel (TC) in the most suitable cell (C1) having the highest signal strength. Unnecessary handoffs are avoided and speech quality is improved.

Claims

1. An arrangement relating to a cellular analogue mobile telesystem which includes:

cells (C1) having base stations (A-G) which have access to traffic channels (TC) and control channels (PC, AC, PAC);

at least one traffic channel cell, which is one of the aforesaid cells (C1) and which includes a geographically restricted area within which all of the traffic channels (TC) dedicated to this area can be used for common predetermined purposes within the whole of said geographically restricted area, wherein said traffic channel cell (C1) has at least two of the control channels (AC, PAC) that are intended for access purposes;

wherein

the base stations (A-G) in predetermined of the traffic channel cells function to transmit in their respective cells (C1) said at least two control channels for access purposes (AC, PAC) with essentially the same power and at least one of the channels for access purposes is a combined control channel (PAC) for both paging the mobile station (MS) and obtaining access thereto;

a mobile station (MS) in the mobile telesystem is adapted to scan at least some of the control channels for access purposes (AC, PAC) and to select the control channel that has the strongest signal strength (S1); and

wherein

when setting up a connection, the mobile station (MS) functions to establish a connection on one of the traffic channels (TC) in the cell (C1) that has the selected access channel,

whereby fading effects are mitigated as a result of providing said at least two control channels for access purposes.

2. An arrangement according to claim 1, wherein the mobile station (MS) functions to scan the channels (PAC, AC) intended for access purposes on at least two occasions spaced a predetermined distance apart in time (Δ

T).

3. The system according to claim 1 wherein the mobile station'"'"'s scanning and selection steps occur when the connection is established.

4. The system according to claim 1 wherein said at least two control channels operate at different frequencies.

5. In a cellular, analogue mobile telesystem a method which comprises:

delimiting at least one geographical area, said at least one area forming a cell (C1) in the mobile telesystem;

allocating traffic channels (TC) in the mobile telesystem, wherein all traffic channels in said at least one cell (C1) can be used for common predetermined purposes throughout the entire cell (C1), which constitutes a traffic channel cell;

allocating at least two control channels (AC, PAC) for access purposes to at least one of the traffic channel cells (C1), wherein at least one of the control channels for access purposes is a combined control channel (PAC) for both paging the mobile station (MS) and for access to said station;

transmitting the control channels (AC, PAC) for access purposes from a base station (A-G) in at least one of the traffic channel cells (C1), wherein the different control channels (AC, PAC) intended for access purposes in a traffic channel cell are transmitted with essentially the same power;

scanning at least a number of the control channels (AC, PAC) intended for access purposes in a mobile station (MS);

selecting the most powerful of the control channels (AC, PAC) for access purposes; and

establishing a connection to the mobile station (MS) via one of the traffic channels (TC) in that cell which has the control channel (AC, PAC) chosen for access purposes ,

whereby fading effects are mitigated as a result of providing the at least two control channels for access purposes.

6. A method according to claim 5, wherein the mobile station (MS) scans the control channels (PAC, AC) intended for access purposes on at least two occasions at a predetermined time distance (Δ

T) apart.

7. The method according to claim 5 wherein the mobile station'"'"'s scanning and selection steps occur when the connection is established.

8. The method according to claim 5 wherein said at least two control channels operate at different frequencies.

9. A mobile cellular system comprising:

a plurality of cells;

wherein at least one of said plurality of cells is equipped with at least two control channels, each operating at different frequencies, which control channels are used for access purposes; and

wherein said at least two control channels transmit with substantially the same power,

whereby fading effects are mitigated as a result of providing the at least two control channels for access purposes.

10. The cellular system according to claim 9 wherein at least one of said at least two control channels is a combined control channel for both paging and access.

11. A method of accessing a radiocommunication system comprising the steps of:

providing a plurality of cells and a plurality of control channels used for access to said system, each cell comprising a base station and at least two of said plurality of control channels;

scanning said plurality of control channels by a mobile station; and

selecting, by said mobile station, one of said plurality of control channels having the strongest signal strength;

wherein said at least two control channels transmit with substantially the same power; and

said at least two control channels used in each cell operate at different frequencies, whereby fading effects are mitigated during said scanning step.

12. The method according to claim 11 wherein at least one of said at least two control channels is a combined control channel for both paging and access.