Channel hopping in a radio communications system

• US 6,298,081 B1
• Filed: 05/30/1997
• Issued: 10/02/2001
• Est. Priority Date: 05/31/1996
• Status: Expired due to Term

• Current Assignee: Unwired Planet LLC (JP Morgan Chase & Co)
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Persson, Yngve Bengt, Olofsson, Håkan Gunnar, Almgren, Knut Magnus
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): BURD, KEVIN MICHAEL
• Application Number:
  US08/866,143
• Time in Patent Office: 1,586 Days
• Field of Search: 375/202, 455/450, 455/451, 455/452, 575/132, 575/133, 575/138
• US Class Current: 375/132
• CPC Class Codes: H04W 72/0466 the resource being a scrambling code
• CPC Class Codes: H04W 72/54 based on quality criteria

Abstract

The invention relates to a method and apparatus for channel hopping between mobile stations (MS1-MS3) and a base station (BS1) in a radio communications system. A channel allocation means (211) within the base station (BS1) generates channel hopping sequences that are transmitted via a control channel (SACCH) to hopping sequence lists (204-206) in the mobile stations (MS1-MS3). The hopping sequences are also transmitted to corresponding hopping sequence lists (201-203) in the base station (BS1). A channel hopping sequence is divided into a number of sequence intervals (T_i) corresponding to the time between two adjacent channel hops within a channel hopping sequence. In the channel allocation means (211) the attenuation (δ) of the connections (F1-F3) and the interference (I(channel,t)) of the channels are continuously being observed within each sequence interval (T_i). The channel allocation means (211) generates channel hopping sequences according to the principle that a connection that has poor connection quality will be allocated a channel hopping sequence with channels of high channel quality and connections with successively better connection quality are allocated channel hopping sequence having successively poorer channels.

Claims

1. A method of channel hopping in accordance with a channel hopping sequence in a radio communications system having at least one first radio station (BS1) and at least one second radio station (MS1-MS3) with information being transmitted between said at least one first and said at least one second radio station on a plurality of connections (F1-F3), said connections being subjected to signal attenuation and interference, wherein the method comprises the steps of:

dividing the channel hopping sequences into sequence intervals (T_i) that together constitute the time taken to run through a channel hopping sequence;

generating a signal attenuation parameter (δ

) for each of the respective connections (F1-F3);

generating a channel quality parameter (I,C/I,BER) within each of the respective sequence intervals (T_i) for frequencies (f1-f6) that are used in the radio communications system, and for different generating intervals (Δ

T_k), wherein a generating interval (Δ

T_k) includes the duration of the whole of a sequence interval (T_i) or for parts of said sequence interval;

generating at least one channel hopping sequence, wherein a channel hopping sequence includes one channel for each sequence interval (T_i), wherein a connection hops between said channels, and wherein said at least one channel hopping sequence is generated in accordance with the generated values of the channel quality parameter (I,C/I,BER);

allocating the channel hopping sequences to a respective connection, wherein said allocation is effected in accordance with the generated values of the channel quality parameter (I,C/I,BER) for each of the sequence intervals of the channels included in the hopping sequences and in accordance with the signal attenuation parameter (δ

); and

channel hopping between the channels included in the channel hopping sequences in radio communication on the connections between the first radio station (BS1) and said second radio stations (MS1-MS3).

2. A method according to claim 1, wherein the channel hopping sequences are stored in a respective hopping sequence list (201-203, 204-206) in the first radio station (BS1) and in said second radio stations (MS1-MS3).

3. A method according to claim 1, wherein the number of channels in a channel hopping sequence and the duration of a sequence interval (T_i) are constant within the radio communications system, and wherein the duration of a sequence interval (T_i) corresponds to the time between two channel hops.

4. A method according to 1, wherein the generating interval (Δ

T_k) includes the whole of the sequence interval (T_i).

5. A method according to 1, wherein the generating interval (Δ

T_k) includes the time of a time slot in a TDMA frame when the radio communications system is a TDMA system, wherein a channel quality parameter is generated for respective sequence intervals (T₁-T₃) and for respective channels (ch1-chy).

6. A method according to claim 5, wherein generation of a channel hopping sequence comprises

selecting a channel in accordance with generated values of the channel quality parameter within the first sequence interval (T₁), said channel forming the channel in the channel hopping sequence that shall be used during the first sequence interval; and

selecting further channels in accordance with the generated values of the channel quality parameter within the remaining sequence intervals (T₂-T₃), said further channels forming those channels in the channel hopping sequence that shall be used during the remaining sequence intervals.

7. A method according to claim 4, wherein generation of the channel hopping sequences further comprises selecting the best channel with respect to the channel quality parameter (I,C/I,BER) within respective sequence intervals (T₁-T₃), wherein said best channels form a best channel hopping sequence;

and

selecting from the remaining channels within respective sequence intervals (T₁-T₃) the best channel with respect to the channel quality parameter, wherein said channels form successively poorer channel hopping sequences with respect to the channel quality parameter in comparison with the best channel hopping sequence.

8. A method according to any claim 4, wherein generation of the channel hopping sequences further comprises

selecting the best channel with respect to the channel quality parameter (I,C/I,BER) within a number of sequence intervals, and selecting the next best channel within remaining sequence intervals, said channels forming a best channel hopping sequence;

selecting the next best channel with respect to the channel quality parameter (I,C/I,BER) within those sequence intervals in which the best channels are included in the best channel hopping sequence, and selecting the best channel within remaining sequence intervals, said channels forming a next best channel hopping sequence; and

selecting successively poorer channel hopping sequences in accordance with the same principle as that applied for the best and the next best channel hopping sequence, wherein the channel selection is made from the remaining channels within respective sequence intervals.

9. A method according to claim 4 where the radio communications system is a TDMA system, wherein generation of the channel hopping sequences further comprises

selecting the best frequency with respect to the channel quality parameter. (I,C/I,BER) within respective sequence intervals (T₁-T₃), said best frequencies forming a best frequency hopping sequence;

selecting the best frequency with respect to the channel quality parameter from the remaining frequencies within respective sequence intervals (T₁-T₃), wherein said frequencies form successively poorer frequency hopping sequences with respect to the channel quality parameter in comparison with the best frequency hopping sequence; and

selecting at least one time slot in a TDMA frame for a respective frequency hopping sequence, wherein each combination of a time slot and a frequency hopping sequence constitutes a channel hopping sequence.

10. A method according to claim 4 where the radio communications system is a TDMA system, wherein generation of the channel hopping sequences further comprises

selecting the best frequency with respect to the channel quality parameter (I,C/I,BER) within a plurality of frequency intervals, and selecting the next best frequency within remaining sequence intervals, said frequencies forming a best frequency hopping sequence;

selecting the next best frequency with respect to the channel quality parameter (I,C/I,BER) within those sequence intervals where the best frequencies are included in the first frequency hopping sequence, and selecting the best frequency within remaining sequence intervals, said frequencies forming a next best frequency hopping sequence;

selecting successively poorer frequency hopping sequences in accordance with the same principle as that applied with respect to the best and the next best frequency hopping sequence, said frequencies being selected from the remaining frequencies within respective sequence intervals; and

selecting at least one time slot in a TDMA frame for respective frequency hopping sequences, wherein each combination of a time slot and a frequency hopping sequence constitutes a channel hopping sequence.

11. A method according to claim 7, comprising

sorting the channels (ch1-chy) for respective sequence intervals (T₁-T₃) with respect to the channel quality parameter (I,C/I,BER);

and

storing the sorted channels in a sorted channel list (407a-407c) for respective sequence intervals (T₁-T₃), wherein the channels for each sequence interval are stored sorted in accordance with the channel quality parameter.

12. A method according to claim 9 comprising

sorting the frequencies (f1-fn) for respective sequence intervals (T₁-T₃) with respect to the channel quality parameter (I,C/I,BER);

and

storing the sorted frequencies in sorted channel lists (307a-307c) for respective sequence intervals (T₁-T₃), wherein the frequencies for each sequence interval are stored sorted in accordance with the channel quality parameter.

13. A method according to claim 11, wherein the selection of channels for the respective channel hopping sequences is effected in accordance with the ranking of the channels in respective sorted channel lists (307a-307c, 407a-407c).

14. A method according to claim 12, wherein selection of frequencies for the respective channel hopping sequences is effected in accordance with the ranking of the frequencies in respective sorted channel list (307a-307c).

15. A method according to claim 7, wherein allocation of channel hopping sequences to the respective connections comprises

selecting the worst connection with respect to the signal attenuation parameter (δ

);

allocating the best channel hopping sequence to the worst connection;

selecting successively better connections with respect to the signal attenuation parameter (δ

); and

allocating the successively poorer channel hopping sequences to the successively better connections.

16. A method according to claim 15, comprising

sorting the connections with respect to the signal attenuation parameter (δ

); and

storing the sorted connections in a sorted connection list (215), wherein said connections are stored sorted in accordance with the signal attenuation parameter (δ

).

17. A method according to claim 16, wherein respective connections (F1-F3) are selected in accordance with their ranking in the sorted connection list (215).

18. A method according to claim 16, wherein the generation of channel hopping sequences further comprises generating a second channel hopping sequence for each already generated channel hopping sequence by means of a duplex spacing, wherein pairs of channel hopping sequences are generated for the connections (F1-F3), and wherein the channels in one pair of channel hopping sequences are mutually separated by the duplex spacing.

19. A method according to claim 6, wherein the generation of channel hopping sequences further comprises generating two channel hopping sequences for respective connections (F1-F3), wherein the channel hopping sequences are generated in accordance with the channel quality parameters (I,C/I,BER) within the respective sequence intervals (T₁-T₃) for both channel hopping sequences.

20. A method according to claim 18, wherein the signal attenuation parameters (δ

) for the connections (F1-F3) are generated by measuring signal attenuation in the uplink.

21. A method according to claim 18, wherein the signal attenuation parameters (δ

) for the connections (F1-F3) are generated by measuring signal attenuation in the downlink.

22. A method according to claim 21, wherein generation of the channel quality parameters (I,C/I,BER) comprises measuring one of the values interference value, C/I value and bit error rate value (BER) in the uplink.

23. A method according to claim 18, wherein generation of the channel quality parameters (I,C/I,BER) comprises measuring one of the values interference value, C/I value and bit error rate value (BER) in the downlink, and forming mean values for the generated values of the channel quality parameter for respective sequence intervals (T₁-T₃) with respect to mutually the same frequencies and mutually the same generating intervals (Δ

T_k).

24. A method according to claim 18, wherein generation of the channel quality parameters (I,C/I,BER) comprises measuring one of the values interference value, C/I value and bit error rate value (BER) in both the uplink and downlink, and forming mean values for the generated values of the channel quality parameter for respective sequence intervals (T₁-T₃) with respect to mutually the same frequencies and mutually the same generating intervals (Δ

T_k).

25. A method according to claim 22, wherein generation of the channel quality parameter (I,C/I,BER) comprises measuring said values for all frequencies and channels included in the radio communications system.

26. A method according to claims 22, wherein generation of the channel quality parameter (I,C/I,BER) comprises measuring said values for a subset of all frequencies and channels included in the radio communications system.

27. A method according to claim 22, wherein generation of the channel quality parameter (I,C/I,BER) includes measuring said values for those channels and frequencies that are allocated to the base station.

28. A method according to claim 8, wherein allocation of the channel hopping sequences to the hopping sequence lists (307a-307c, 407a-407c) comprises transferring one of the channel hopping sequences in said pair to a hopping sequence list (201-203, 204-206) in the base station (BS1) and the other to the mobile stations (MS1-MS3).

29. (Amended) A method according to claim 28, comprising transferring the channel hopping sequences to the hopping sequence lists (204-206) of the mobile stations (MS1-MS3) via a control channel.

30. Apparatus in radio communications system comprising a first radio station (BS1) that communicates with at least one second radio station (MS1-MS3) via channels (f1-fn, chl-chy), wherein channel hopping is effected in accordance with channel hopping sequences where each channel hopping sequence is divided into a number of sequence intervals (T_i) for connections (F1-F3) between the first radio station and each of the second radio stations, and wherein the connections are subjected to signal attenuation and interference, wherein said apparatus includes

means (212) for generating a signal attenuation parameter (δ

) for each of the respective connections (F1-F3);

means (216) for generating a channel quality parameter (I,C/I,BER) within each of the respective sequence intervals (T_i) for each of said frequencies (f1-fin) and for different generating intervals (Δ

T_k), where a generating interval includes the time for the whole of a sequence interval (T_i) or for parts of said sequence interval; and

means (220) for generating at least one channel hopping sequence for each of the respective connections, wherein a channel hopping sequence includes a channel (fi-fn, chl-chy) for each sequence interval (T_i), wherein respective channels within respective sequence intervals are chosen in accordance with the generated values of the channel quality parameter (I,C/I,BER), wherein said means for generating at least one channel hopping sequence (220) allocates a channel hopping sequence to each connection (F1-F3) in accordance with the generated signal attenuation parameter (δ

) for respective connections (F1-F3) and in accordance with the generated values of the channel quality parameter (I,C/I,BER) for each of the sequence intervals of the channels included in the channel hopping sequences.

31. Apparatus according to claim 30, comprising

at least one receiver (207) in the first radio station (BS1) and at least one receiver (208-210) in each second radio station (MS1-MS3) for receiving said signal values, wherein said signal values are delivered to said means (216) for generating said channel quality parameter, and to said means (212) for generating said signal attenuation parameter; and

means (CPU) for controlling channel hopping in the radio communications system.

32. Apparatus according to claim 31, comprising

means (214) for sorting the connections with respect to said signal attenuation parameter (δ

); and

means (215) for storing the sorted connections, wherein said connections are stored sorted in accordance with said signal attenuation parameter (δ

).

33. Apparatus according to claim 31, wherein the means (216) for generating a channel quality parameter includes

a sequence counter (303, 403) that indicates the sequence interval (T_i) in which the channel hopping sequence is located;

at least one mean value forming means (304a-304c, 404a-404c) which during each generating interval (Δ

T_k) form mean values from measurement values of the channel quality parameter (I,C/I,BER) for each frequency (f1-fn) and store said values in a channel quality list (305a-305c, 405a-405c) for respective sequence intervals (T_i);

a multiplexor means (302, 402) which connects the receiver (207) to one of a number of mean value forming means (304a-304c, 404a-404c) in accordance with the sequence interval (T_i) indicated by the sequence counter (302, 403);

sorting means (306a-306c, 406a-406c) operable to sort frequencies (f1-fn) and channels (chl-chy) for respective sequence intervals (T_i) in the radio communications system with respect to the channel quality parameter (I,C/I,BER); and

means (307a-307c, 407a-407c) for storing the sorted frequencies (f1-fn) and channels (chl-chy) in accordance with the channel quality parameter (I,C/I,BER) of respective sequence intervals (T_i).

34. A method of generating channel hopping sequences in a radio communications system with information being transmitted between a first radio station and at least one second radio station on a plurality of connections (F1-Fn), comprising:

dividing a channel hopping sequence into sequence intervals (T_i) that together constitute the time taken to run through the channel hopping sequence;

generating a signal attenuation parameter (δ

) for each of the respective connections (F1-Fn);

generating a channel quality parameter (I,C/I,BER) within each of the respective sequence intervals (T_i) for frequencies (f1-fn) that are used in the radio communications system, and for different generating intervals (Δ

T_k), wherein a generating interval (Δ

T_k) includes the duration of the whole of a sequence interval (T_i) or for parts of said sequence interval;

generating at least one channel hopping sequence, wherein the at least one channel hopping sequence includes one channel for each sequence interval (T_i), wherein a connection hops between said channels, and wherein said at least one channel hopping sequence is generated in accordance with the generated values of the channel quality parameter (I,C/I,BER); and

allocating the at least one generated channel hopping sequence to a respective connection, wherein said allocation is effected in accordance with the generated values of the channel quality parameter (I,C/1,BER) for each of the sequence intervals of the channels included in the generated channel hopping sequence and in accordance with the signal attenuation parameter (δ

).