Inter-frequency handoff execution method and apparatus in mobile communication system

• US 6,563,807 B1
• Filed: 12/16/1998
• Issued: 05/13/2003
• Est. Priority Date: 12/30/1997
• Status: Expired due to Term

• Current Assignee: LG Information & Communications Ltd. (LG Corporation)
• Original Assignee: LG Information & Communications Ltd. (LG Corporation)
• Inventors: Kim, Jong Heon, Kim, Jong Youn
• Primary Examiner(s): Kizou, Hassan
• Assistant Examiner(s): Tsegaye, Saba
• Application Number:
  US09/212,573
• Time in Patent Office: 1,609 Days
• Field of Search: 370/310, 370/320, 370/331, 370/335, 370/342, 370/343, 370/441, 370/479, 370/470, 455/436, 455/439, 455/442, 455/444
• US Class Current: 370/331
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04W 36/0088 Scheduling hand-off measurements
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 36/12 Reselecting a serving backbone network switching or routing node
• CPC Class Codes: H04W 36/32 by location or mobility data, e.g. speed data
• CPC Class Codes: H04W 36/324 by mobility data, e.g. speed data
• CPC Class Codes: H04W 52/40 during macro-diversity or soft handoff

Abstract

An inter-frequency handoff execution method in a mobile communication system according to the present invention includes the steps of: transmitting from a base station a data frame in which a data transmission section and a frequency search section exist to an arbitrary mobile terminal; executing data transmission in the data transmission section; searching a frequency of other base station in the frequency search section; and determining whether or not handoff is executed in accordance with the searched result.

Claims

1. An inter-frequency handoff execution method in a mobile communication system, comprising:

forming a plurality of subframes from a data frame, each having a data transmission section for transmitting frame data and a frequency search section;

transmitting the plurality of subframes from a base station to an arbitrary mobile terminal;

executing data transmission of the frame data in the data transmission section;

searching a frequency of other base station in the frequency search section; and

determining whether or not handoff is executed in accordance with the searched result, wherein frame data in each of the plurality of subframes is interleaved independently of the other subframes to achieve a different arrangement pattern in each of the plurality of subframes, and wherein a transmitting power of said plurality of subframes is adjusted in accordance with a repetition number and a number of subframes.

2. The method as defined in claim 1, wherein said frequency search section is inserted into an arbitrary position of said data frame under the agreement of said base station and said mobile terminal.

3. The method as defined in claim 2, wherein said handoff execution is determined by comparing frequency strength of said base station currently communicated with said mobile terminal with that of the frequency-searched other base station is executed and then in accordance with the compared result.

4. The method of claim 1, wherein the different arrangement pattern in each of the plurality of subframes provides for a time diversity of the data transmission.

5. The method of claim 1, further comprising adjusting an energy per bit for each of the subframes.

6. The method of claim 5, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during the search section multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame.

7. The method as defined in claim 6, wherein determining whether a handoff can be executed comprises comparing frequency strength of a current base station currently with that of a frequency-searched base station.

8. An inter-frequency handoff execution method in a mobile communication system, comprising:

dividing a data frame which is transmitted from a base station to a mobile station into a plurality of subframes, each one of the plurality of subframes having an interleaved pattern that is different from the other subframes;

generating a frequency search period in each of said plurality subframes;

adjusting a transmission power of said plurality of subframes in accordance with a repetition number and a number of subframes;

spreading and transmitting each of said plurality of subframes using spreading sequences different from each other;

receiving said plurality of subframes and searching a frequency of other base stations during the frequency search period; and

determining whether or not handoff is executed in accordance with the searched result.

9. The method as defined in claim 8, further comprising differentiating transmission patterns of said plurality of subframes from each other, after completion of said frequency search section inserting step.

10. The method as defined in claim 8, wherein searching the frequency of the other base station is comprises adjusting a frequency synthesizer in said base station to tune a current frequency to another frequency and executing state check and an initial synchronization of the another frequency.

11. The method as defined in claim 8, wherein said frequency search section is formed by the insertion of time (1−

α

) T_frame in the data frame having an arbitrary transmission rate (where, 0≦

α

≦

1).

12. The method of claim 8, further comprising transmitting each of the plurality of subframes using a spreading sequence that is different than the spreading sequence used for the other subframes among the plurality of subframes.

13. An inter-frequency handoff execution method in a mobile communication system, comprising:

dividing a data frame which is transmitted from a base station to a mobile station into a plurality of subframes, each one of the plurality of subframes having an interleaved pattern that is different from the other subframes;

generating a frequency search period in each of said plurality subframes;

spreading and transmitting each of said plurality of subframes using spreading sequences different from each other;

adjusting a transmission power of said plurality of subframes in accordance with a repetition number;

receiving said plurality of subframes and searching a frequency of other base stations during the frequency search period; and

determining whether or not handoff is executed in accordance with the searched result.

14. The method of claim 13, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during the search period multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame.

15. An inter-frequency handoff execution method in a mobile communication system, comprising:

transmitting from an arbitrary mobile terminal to a corresponding base station a plurality of data subframes, each of the plurality of subframes having a data transmission section and a frequency search section;

executing data transmission in the data transmission section; and

transmitting a reverse link pilot signal and a preamble signal in the frequency search section, wherein each of the plurality of subframes is subjected to interleaving and spreading independently of the other subframes.

16. The method as defined in claim 15, wherein said frequency search section is inserted into an arbitrary position of said data frame under the agreement of said base station and said mobile terminal.

17. The method of claim 15, where in each of the subframes has an interleaved pattern that is different from the other subframes.

18. The method of claim 15, where in an original data frame is converted to the plurality of subframes for transmission.

19. The method of claim 18, wherein the original data frame is demultiplexed into the plurality of subframes.

20. The method of claim 18, further comprising receiving the plurality of subframes and multiplexing them into the original data frame.

21. The method of claim 15, further comprising adjusting an energy per bit for each of the subframes.

22. The method of claim 21, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during the search period multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame.

23. The method of claim 15, further comprising adjusting an energy per bit for each of the subframes in accordance with a repetition number and a number of subframes.

24. The method of claim 15, further comprising adjusting an energy per bit for each of the subframes, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during the search section multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame.

25. The method of claim 15, further comprising transmitting each of the plurality of subframes using a spreading sequence that is different than the spreading sequence used for the other subframes among the plurality of subframes.

26. An inter-frequency handoff execution method in a mobile communication system, comprising:

dividing a data frame into a plurality of subframes and inserting a frequency search section into said data frame;

interleaving each of the plurality of subframes independently such that each subframe has a pattern that is different from the other subframes;

spreading said plurality of subframes to spreading sequences different from each other and transmitting the spread subframes;

transmitting the plurality of subframes from an arbitrary mobile terminal to a corresponding base station;

receiving said plurality of subframes to thereby restore one frame; and

transmitting a reverse link pilot signal and a preamble signal in the frequency search section and determining whether or not handoff is executed.

27. The method as defined in claim 26, wherein transmitting said subframes is executed by the completion of tuning to a frequency of the base station currently communicated with the mobile terminal.

28. The method as defined in claim 26, wherein said frequency search section is formed by the insertion of time (1−

α

) T_frame in the data frame having an arbitrary transmission rate(where, 0≦

α

≦

1).

30. The method of claim 26, further comprising adjusting an energy per bit for each of the subframes.

31. The method of claim 30, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during the search period multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame.

32. The method of claim 26, further comprising adjusting an energy per bit for each of the subframes in accordance with a repetition number and a number of subframes.

33. The method of claim 26, further comprising adjusting an energy per bit for each of the subframes, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during the search section multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame.

34. The method of claim 26, further comprising transmitting each of the plurality of subframes using a spreading sequence that is different than the spreading sequence used for the other subframes among the plurality of subframes.

29. The method of claimed 26, wherein interleaving each of the plurality of subframes independently achieves time diversity in transmission.

35. An inter-frequency handoff execution apparatus in a mobile communication system, comprising:

a frame encoder for changing data to be sent to a data frame;

a demultiplexer for dividing the data frame into a plurality of subframes;

a plurality of subframe interleavers for making patterns of said subframes outputted from said demultiplexer different from each other;

a plurality of spreaders for modulating each of said plurality of subframes to different spreading sequences;

a plurality of gain adjusters configured to adjust an energy per bit for each of the plurality of subframes, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during a search section of the subframe multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame;

an adder for adding each of said plurality of subframes; and

an RF transmitter for transmitting the frame outputted from said adder.

36. The apparatus as defined in claim 35, wherein each of said subframe interleavers is disposed on a rear end of said demultiplexer or on a front end of said demultiplexer as an integrated body therewith.

37. The apparatus as defined in claim 35, further comprising a plurality of gain adjusters for adjusting gains of output signals from said plurality of spreaders, said gain adjusters being each disposed on the rear end of said plurality of spreaders or on the front end of said demultiplexer as an integrated body therewith.

38. The apparatus of claim 35, further comprising transmitting each of the plurality of subframes using a spreading sequence that is different than the spreading sequence used for the other subframes among the plurality of subframes.

39. An inter-frequency handoff execution apparatus in a mobile communication system, comprising:

an RF receiver for receiving a frame transmitted from a transmitter;

a plurality of despreaders for removing spreading sequences of a plurality of subframes of the frame outputted from said RF receiver, each of the subframes having a different spreading sequence;

a plurality of subframe deinterleavers for making patterns of said subframes different from each other;

a multiplexer for restoring said plurality of subframes transmitted from said plurality of despreaders to an original frame;

a frame decoder for decoding the frame outputted from said multiplexer to original data;

a frequency synthesizer for tuning a frequency of other base station;

a searcher for searching the frequency of the other base station; and

a controller for providing the searched frequency information of the other base station to said frequency synthesizer, wherein the transmitter comprises a plurality of gain adjusters configured to adjust an energy per bit for each of the plurality of subframes, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during a search section of the subframe multiplied by an optical energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame.

40. The apparatus as defined in claim 39, wherein each of said subframe deinterleavers is disposed on a rear end of said despreaders or on a rear end of said demultiplexer as an integrated body therewith.

41. The method of claim 39, wherein the spreading sequences of each of the plurality of subframes of the frame outputted from said RF receiver are spread using a spreading sequence that is different than the spreading sequence used for the other subframes among the plurality of subframes.

42. A method of performing an inter-frequency handoff in a mobile communication system, comprising:

dividing a data frame into a plurality of sub-frames, each sub-frame having a data component and a searching period;

separately interleaving and spreading each sub-frame for transmission;

transmitting each of the plurality of sub-frames and adjusting a transmitting power of said plurality of subframes in accordance with a repetition number and a number of subframes;

searching for a frequency of a target base station during the searching period of each sub-frame; and

determining whether a handoff can be executed in accordance with a result of the search for a frequency.

43. The method of claim 42, wherein determining whether the handoff can be executed comprises comparing a frequency strength of a current base station with a frequency strength of a frequency-searched base station.

44. The method of claim 42, further comprising adjusting an energy per bit for each of the subframes.

45. The method of claim 42, further comprising transmitting each of the plurality of subframes using a spreading sequence that is different than the spreading sequence used for the other subframes among the plurality of subframes.

46. A method of performing an inter-frequency handoff in a mobile communication system, comprising:

dividing a data frame into a plurality of sub-frames, each sub-frame having a data component and a searching period;

separately interleaving and spreading each sub-frame for transmission;

adjusting an energy per bit for each of the subframes, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during the searching period multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame;

transmitting each of the plurality of sub-frames;

searching for a frequency of a target base station during the searching period of each sub-frame;

determining whether a handoff can be executed in accordance with a result of the search for a frequency.

47. An inter-frequency handoff execution method in a mobile communication system, comprising:

dividing a frame of data which is transmitted from a base station to a mobile station into a plurality of subframes applied by a time diversity respectively;

generating a frequency search period into each of said plurality of subframes;

spreading and transmitting each of said plurality of subframes using spreading sequences different from the spreading sequence uses for the other subframes among the plurality of subframes and adjusting a tansmitting power of said plurality of subframes in accordance with a repetition number, a period of information in the subframe, and a number of subframes;

receiving the spread subframes and searching a frequency of other base station in the frequency search period;

determining whether or not a handoff can be executed in accordance with the searched result.

48. An inter-frequency handoff execution apparatus in a mobile communication system, comprising:

a frame encoder for changing data to be sent to a data frame;

a demultiplexer for dividing the data frame into a plurality of subframes;

a plurality of subframe interleavers for making patterns of said subframes outputted from said demultiplexer different from each other;

a plurality of spreaders for modulating each of said plurality of subframes to different spreading sequences;

a plurality of gain adjusters configured to adjust an energy per bit for each of the plurality of subframes, wherein the energy per bit is adjusted in accordance with a repetition number and a number of subframes;

an adder for adding each of said plurality of subframes; and

an RF transmitter for transmitting the frame outputted from said adder.

49. An inter-frequency handoff execution apparatus in a mobile communication system, comprising:

an RF receiver for receiving a frame transmitted from a transmitter;

a plurality of despreaders for removing spreading sequences of a plurality of subframes of the frame outputted from said RF receiver, each of the subframes having a different spreading sequence;

a plurality of subframe deinterleavers for making patterns of said subframes different from each other;

a multiplexer for restoring said plurality of subframes transmitted from said plurality of despreaders to an original frame;

a frame decoder for decoding the frame outputted from said multiplexer to original data;

a frequency synthesizer for tuning a frequency of other base station;

a searcher for searching the frequency of the other base station; and

a controller for providing the searched frequency information of the other base station to said frequency synthesizer, wherein the transmitter comprises a plurality of gain adjusters configured to adjust an energy per bit for each of the plurality of subframes, wherein the energy per bit is adjusted in accordance with a repetition number and a number of subframes.

50. A method of performing inter frequency handoff in a mobile communication system, comprising:

dividing a data frame having a repetition symbol which is transmitted from a base station to a mobile station into a plurality of sub-frames;

generating a frequency searching period into the data frame by spreading the plurality of sub-frames with a sequence set having different spreading sequences respectively;

adjusting an energy per bit for the plurality of sub-frames in accordance with one of a repetition number and a number of subframes;

transmitting the data frame with the frequency searching period on a channel;

receiving and searching a frequency of other base station in the frequency search period; and

determining whether or not handoff is executed in accordance with the searched result.

51. The method of claim 50, further comprising transmitting each of the plurality of subframes using a spreading sequence that is different than the spreading sequence used for the other subframes among the plurality of subframes.

52. A method of performing inter frequency handoff in a mobile communication system, comprising:

dividing a data frame having a repetition symbol which is transmitted from a base station to a mobile station into a plurality of sub-frames;

generating a frequency searching period into the data frame by spreading the plurality of sub-frames with a sequence set having different spreading sequences respectively;

adjusting an energy per bit for the plurality of sub-frames, wherein the energy per bit is adjusted in accordance with a product of a spare energy provided during the search section multiplied by an original energy per bit, divided by a product of a number of subframes multiplied by a number of repetitions in the original frame;

transmitting the data frame with the frequency searching period on a channel;

receiving and searching a frequency of other base station in the frequency search period; and

determining whether or not handoff is executed in accordance with the searched result.