FREQUENCY HOPPING

• US 20100111139A1
• Filed: 01/30/2008
• Published: 05/06/2010
• Est. Priority Date: 02/05/2007
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Awad, Yassin Aden, Arnott, Robert
• Granted Patent: US 8,170,080 B2
• Time in Patent Office: Days
• US Class Current: 375/133
• CPC Class Codes: H04B 1/7143 Arrangements for generation of hop patterns
• CPC Class Codes: H04B 2201/71323 Adaptive systems
• CPC Class Codes: H04B 7/2621 using frequency division multiple access [FDMA] H04B7/2615 takes precedence
• CPC Class Codes: H04L 5/0005 Time-frequency
• CPC Class Codes: H04L 5/0039 Frequency-contiguous, i.e. with no allocation of frequencies for one user or terminal between the frequencies allocated to another
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/0453 Resources in frequency domain, e.g. a carrier in FDMA

Abstract

A communications system is described in which user devices communicate with an associated base station. The user devices employ frequency hopping techniques to provide frequency diversity in their communications with the base station. Techniques are described for reducing collisions between the communications from the different user devices and for the efficient signalling of data defining the frequency hopping sequence to use. The inventions are particularly suitable for use in the uplink of the E-UTRA communications scheme.

Claims

1. A communications node operable to communicate with another communications node over a communications channel having a plurality of frequency resources, the communications node comprising:

data defining a division of the communications channel into a plurality of contiguous sub-bands each having N frequency resources;

data defining an initial allocation of said frequency resources;

a resource determination module operable to apply a frequency shift to the initially allocated frequency resource in accordance with a frequency hopping sequence to determine a frequency resource to use for communicating information with the other communications node, the frequency shift corresponding to an integer number of said sub-bands; and

a communicating portion communicating information with the other communications node using the determined frequency resource.

2. A communications node according to claim 1, wherein said resource determination module is operable to apply a frequency shift that is an integer multiple of N.

3. A communications node according to claim 1, wherein each frequency resource in a sub-band has a corresponding frequency resource in each of the other sub-bands and wherein the resource determination module is operable to apply a frequency shift that moves the initially allocated frequency resource to a corresponding frequency resource in another sub-band.

4. A communications node according to claim 1, wherein said data defining said initial allocation defines an initial allocation of a plurality of said frequency resources in the same sub-band.

5. A communications node according to claim 1, wherein said resource determination module is operable to apply a frequency shift to the initially allocated frequency resource in accordance with the following equation:

y={x+a(t)N} mod N_RB,

where

N_RB is the total number of frequency resources in the transmission band;

N is the number of contiguous frequency resources in each sub-band;

X is the initially allocated frequency resource;

Y is the frequency hopped resource;

T is a time counter;

a(t) is the frequency hopping shift applied at time point t, and is an integer value from the set {0, 1, . . . , S−

1}; and

S is the number of sub-bands.

6. A communications node according to claim 1, wherein said resource determination module is operable to apply a frequency shift to its initially allocated frequency resource in accordance with a pseudo-random frequency hopping sequence.

7. A communications node according to claim 1, wherein said resource determination module is operable to dynamically calculate the frequency shift to be applied at a given time point using a predetermined equation.

8. A communications node according to claim 7, wherein the resource determination module is operable to dynamically calculate the frequency shift to be applied at a given time point using an equation that involves a pseudo-random value.

9. A communications node according to claim 8, further comprising a shift register circuit for generating, at each time point, said pseudo-random value.

10. A communications node according to claim 9, wherein the resource determination module is operable to calculate the frequency shift to be applied at a given time point, t, using the following equation:

a(t)=floor[(m(t)·

S)/2^M],

where

a(t) is the frequency hopping shift to be applied at time point t;

m(t) is the pseudo-random value generated by the shift register circuit at time point t;

S is the number of sub-bands; and

M is the number of registers in the shift register circuit.

11. A communications node according to claim 9, wherein the resource determination module is operable to calculate the frequency shift to be applied at a given time point, t, using the following equation:

a(t)={a(t−

1)+1+floor[(m(t)·

(S−

1))/2^M]} mod S,

where

a(t) is the frequency hopping shift to be applied at time point t;

a(t−

1) is the frequency hopping shift applied at the previous time point, t−

1;

m(t) is the pseudo-random value generated by the shift circuit at time point t;

S is the number of sub-bands; and

M is the number of registers in the shift register.

12. A communications node according to claim 1, wherein said communicating portion is operable to transmit information to said other communications node using the determined frequency resource.

13. A communications node according to claim 1, wherein said communicating portion is operable to receive information from said other communications node using the determined frequency resource.

14. A communications node according to claim 1, which is a user device preferably selected from the group consisting of:

a cellular telephone, a personal digital assistant, a laptop computer and a web browser.

15. A communications node according to claim 1, which is a base station.

16. A base station according to claim 15, operable to communicate with a plurality of other communications nodes;

wherein the base station includes data defining an initial allocation of said frequency resources for each of said other communications nodes;

wherein said resource determination module is operable to apply a common frequency shift to the initially allocated frequency resource for each other communications node to determine a respective frequency resource to use for communicating information with each other communications node; and

wherein said communicating portion is operable to communicate information with the other communications nodes using the determined frequency resource for the other communications nodes.

17. A communications system comprising:

a communications node and a plurality of user devices operable to communicate with the communications node over a communications channel;

wherein the communications channel includes a transmission bandwidth, having a plurality of frequency resources, that is divided into a plurality of contiguous sub-bands each having N frequency resources;

wherein each user device has a respective initial allocation of said frequency resources to use for communications with said communications node; and

wherein each user device is operable to apply a frequency shift to its initially allocated frequency resource in accordance with a frequency hopping sequence, the frequency shift corresponding to an integer number of said sub-bands.

18. A communications system according to claim 17, wherein one or more of the user devices is a user device selected from the group consisting of:

a cellular telephone, a personal digital assistant, a laptop computer and a web browser and/or wherein the communications node is a base station comprising;

data defining a division of the communications channel into a plurality of contiguous sub-bands each having N frequency resources;

data defining an initial allocation of said frequency resources;

a resource determination module operable to apply a frequency shift to the initially allocated frequency resource in accordance with a frequency hopping sequence to determine a frequency resource to use for communicating information with the other communications node, the frequency shift corresponding to an integer number of said sub-bands; and

a communicating portion communicating information with each user device using the determined frequency resource.

19. A method performed in a communications node which communicates with another communications node over a communications channel having a plurality of frequency resources, the method comprising:

defining a division of the communications channel into a plurality of contiguous sub-bands each having N frequency resources;

defining an initial allocation of said frequency resources;

applying a frequency shift to the initially allocated frequency resource in accordance with a frequency hopping sequence to determine a frequency resource to use for communicating data with the other communications node, the frequency shift corresponding to an integer number of said sub-bands; and

communicating information with the other communications node using the determined frequency resource.

20. A method according to claim 19, wherein said applying applies a frequency shift that is an integer multiple of N.

21. A method according to claim 19, wherein each frequency resource in a sub-band has a corresponding frequency resource in each of the other sub-bands and wherein the applying applies a frequency shift that moves the initially allocated frequency resource to a corresponding frequency resource in another sub-band.

22. A method according to claim 19, wherein said defining said initial allocation defines an initial allocation of a plurality of said frequency resources in the same sub-band.

23. A method according to claim 19, wherein said applying p applies a frequency shift to the initially allocated frequency resource in accordance with the following equation:

y={x+a(t)N} mod N_RB,

where

N_RB is the total number of frequency resources in the transmission band;

N is the number of contiguous frequency resources in each sub-band;

x is the initially allocated frequency resource;

t is a time counter;

a(t) is the frequency hopping shift applied at time point t, and is an integer value from the set {0, 1, . . . , S−

1}; and

S is the number of sub-bands.

24. A method according to claim 19, wherein said applying applies a frequency shift to its initially allocated frequency resource in accordance with a pseudo-random frequency hopping sequence.

25. A method according to claim 19, further comprising dynamically calculating the frequency shift to be applied at a given time point using a predetermined equation.

26. A method according to claim 25, wherein the dynamically calculating the frequency shift to be applied at a given time point uses an equation that involves a pseudo-random value.

27. A method according to claim 26, further comprising using a shift register circuit to generate, at each time point, said pseudo-random value.

28. A method according to claim 27, wherein the dynamic calculation calculates the frequency shift to be applied at a given time point, t, using the following equation:

a(t)=floor[(m(t)·

S)/2^M],

where

a(t) is the frequency hopping shift to be applied at time point t;

m(t) is the pseudo-random value generated by the shift register circuit at time point t;

S is the number of sub-bands; and

M is the number of registers in the shift register circuit.

29. A method according to claim 27, wherein the dynamic calculating calculates the frequency shift to be applied at a given time point, t, using the following equation:

a(t)={a(t−

1)+1+floor[(m(t)·

(S−

1))/2^M]} mod S,

where

a(t) is the frequency hopping shift to be applied at time point t;

a(t−

1) is the frequency hopping shift applied at the previous time point, t−

1;

m(t) is the pseudo-random value generated by the shift circuit at time point t;

S is the number of sub-bands; and

M is the number of registers in the shift register.

30. A method according to claim 19, wherein said communicating transmits information to said other communications node using the determined frequency resource.

31. A method according to claim 19, wherein said communicating receives information from said other communications node using the determined frequency resource.

32. A method according to claim 19, performed in a user device preferably selected from the group consisting of:

a cellular telephone, a personal digital assistant, a laptop computer and a web browser.

33. A method according to claim 19, performed in a base station.

34. A method according to claim 33, in which the base station communicates with a plurality of other communications nodes and further comprising:

defining an initial allocation of said frequency resources for each of said other communications nodes;

applying a common frequency shift to the initially allocated frequency resource for each other communications node to determine a respective frequency resource to use for communicating information with each other communications node; and

wherein said communicating communicates information with the other communications nodes using the determined frequency resource for the other communication nodes.

35. A computer implementable instructions product comprising computer implementable instructions for causing a programmable computer device to carry out the method of claim 19.

36. A cellular communications system comprising:

a base station and a plurality of user devices;

wherein each user device is operable to communicate with the base station over a communication channel having a plurality of frequency resources;

wherein the base station is operable;

i) to provide each user device with a respective initial allocation of said frequency resources; and

ii) to provide at least one user device with a periodic communications opportunity in which the user device can communicate with the base station;

wherein each user device is operable to apply a frequency shift to its initially allocated frequency resource in accordance with a frequency hopping sequence;

wherein the user devices use the same frequency hopping sequence and are synchronised with each other so that, at any point in time, a common frequency shift is applied by the user devices; and

wherein the frequency hopping sequence used by the user devices is periodic and has a period that is greater than the periodicity of the periodic communications opportunity provided to said at least one user device.

37. A cellular communications system according to claim 36, wherein the frequency hopping sequence used by the user devices has a period that is greater than five times the periodicity of the periodic communications opportunity provided to said at least one user device.

38. A cellular communications system according to claim 36, wherein the frequency hopping sequence used by the user devices has a period that is greater than ten times the periodicity of the periodic communications opportunity provided to said at least one user device.

39. A cellular communications system according to claim 36, wherein the communications channel is divided into a plurality of contiguous sub-bands and wherein the frequency hopping sequence used by the user devices has a period that is greater than the periodicity of the periodic communications opportunity provided to said at least one user device times the number of said sub-hands.

40. A cellular communications system according to claim 39, wherein each frequency resource in a sub-band has a corresponding frequency resource in each of the other sub-bands and wherein each user device is operable to apply a frequency shift that moves the initially allocated frequency resource to a corresponding frequency resource in another sub-band.

41. A cellular communications system according to claim 36, wherein the communications channel is divided into a plurality of contiguous sub-bands and wherein said user devices are operable to apply a frequency shift to its initially allocated frequency resource in accordance with the following equation:

y={x+a(t)N} mod N_RB,

where

N_RB is the total number of frequency resources in the transmission band;

N is the number of contiguous frequency resources in each sub-band;

X is the initially allocated frequency resource;

T is a time counter;

a(t) is the frequency hopping shift applied at time point t, and is an integer value from the set {0, 1, . . . , S−

1}; and

S is the number of sub-bands.

42. A cellular communications system according to claim 36, wherein said user devices are operable to apply a frequency shift to its initially allocated frequency resource in accordance with a pseudo-random frequency hopping sequence.

43. A cellular communications system according to claim 36, wherein said user devices are operable to dynamically calculate the frequency shift to be applied at a given time point using a predetermined equation.

44. A cellular communications system according to claim 43, wherein the user devices are operable to dynamically calculate the frequency shift to be applied at a given time point using an equation that involves a pseudo-random value.

45. A cellular communications system according to claim 44, further comprising a shift register circuit for generating, at each time point, said pseudo-random value.

46. A cellular communications system according to claim 45, wherein the shift register circuit has M registers and can generate a sequence of pseudo random values up to 2^M in length and wherein said user devices are operable to periodically reset said shift register in synchronism with the periodicity of the frequency hopping sequence.

47. A cellular communications system according to claim 45, wherein the user device is operable to control the frequency hopping sequence to be used by setting an initial state of said shift register each time it is reset to one of a predetermined number of possible initialisation states.

48. A cellular communications system according to claim 47, wherein said base station is operable to signal which initialisation state is to be used by each user device.

49. A communications method characterised by using a system according to claim 36.

50. A computer implementable instructions product comprising computer implementable instructions for causing a programmable computer device to become configured as the user device of claim 36.

51. A cellular communications system comprising:

a plurality of base stations and a plurality of user devices;

wherein, in use, each user device is associated with a base station and is operable to communicate with the associated base station over a communication channel having a plurality of frequency resources;

wherein each user device has a respective initial allocation of said frequency resources;

wherein each user device is operable to apply a frequency shift to its initially allocated frequency resource in accordance with a frequency hopping sequence;

wherein the user devices that are associated with the same base station are operable, in use, to use the same frequency hopping sequence and are synchronised with each other so that, at any point in time, a common frequency shift is applied by the user devices associated with the same base station; and

wherein user devices associated, in use, with different base stations use different frequency hopping sequences.

52. A communication method between a plurality of base stations and a plurality of user devices, the method comprising:

associating each user device with a base station;

communicating information between the plurality of user devices and the associated base station over a communication channel having a plurality of frequency resources;

wherein each user device has a respective initial allocation of said frequency resources;

applying, in each user device, a frequency shift to its initially allocated frequency resource in accordance with a frequency hopping sequence;

using the same frequency hopping sequence for all user devices that are associated with the same base station;

synchronising the user devices associated with the same base station so that, at any point in time, said applying step uses a common frequency shift for all the user devices associated with the same base station; and

using different frequency hopping sequences in the user devices associated with different base stations.