ORTHOGONAL FREQUENCY AND CODE HOPPING MULTIPLEXING COMMUNICATIONS METHOD

• US 20100165952A1
• Filed: 12/08/2005
• Published: 07/01/2010
• Est. Priority Date: 12/08/2004
• Status: Active Grant

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Moon, Sung-ho, Kim, Jun-Su, Jung, Bang-chul, Chung, Jae-hoon, Hong, Young-jun, Seo, Young-ik, Sung, Dan-keun
• Granted Patent: US 8,094,547 B2
• Time in Patent Office: Days
• US Class Current: 370/335
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04L 5/026 using code division

Abstract

An Orthogonal Frequency and Code Hopping Multiplexing (OFCHM) communication method based Orthogonal Frequency Division Multiplexing (OFDM) in a wireless communication system in which a plurality of communication channels are synchronized through a single medium. Six types of spreading and hopping methods are included, a method of controlling spreading and hopping depending on channel states, and a method of determining whether radio resources, consisting of subcarriers and orthogonal codewords, are allocated in a hopping manner according to the quality of service in the OFCHM communication method based OFDM. Furthermore, an embodiment employing six multiple array antennas is included. For this purpose, a method of combining a collision comparator and controller for monitoring the operations of a subcarrier group hopping pattern generator and an orthogonal code hopping pattern generator, a multiplexer and data symbol mapper, and the collision of hopping patterns that are composed of subcarriers and orthogonal codewords, and comparing data symbols to be transmitted to second communication stations to determine whether the data symbols collide in a symbol interval, a beam-forming processor for managing the operation of multiple array antennas, and a weighting vector controller is proposed.

Claims

1. An Orthogonal Frequency and Code Hopping Multiplexing (OFCHM) communication method based an Orthogonal Frequency Division Multiplexing (OFDM) in a digital communication system having a first communication station and one or more second communication stations, a system for efficiently multiplexing communication channels from the first communication station to the second communication stations being provided,

wherein the communication channels are multiplexed.

2. The OFCHM communication method according to claim 1, wherein the multiplexing comprises the steps of:

spreading data symbols, to be transmitted to the second communication stations and multiplexed by the first communication station, based on arbitrary spreading factors;

assigning the spread data symbols to a single OFDM subcarrier only along a time axis; and

multiplexing the spread data symbols to be transmitted to the second communication stations, which are assigned to the single subcarrier at the spreading and assignment steps while performing hopping using only orthogonal codewords.

3. The OFCHM communication method according to claim 1, wherein the multiplexing comprises the steps of:

spreading data symbols, to be transmitted to the second communication stations and multiplexed by the first communication station, based on arbitrary spreading factors;

assigning the spread data symbols to a OFDM-based single subcarrier only along a time axis; and

multiplexing the spread data symbols to be transmitted to the second communication stations, which are assigned at the spreading and assignment steps, while performing hopping on the data symbols using both orthogonal subcarriers and orthogonal codewords.

4. The OFCHM communication method according to claim 1, wherein the multiplexing comprises the steps of:

spreading data symbols, to be transmitted to the second communication stations and multiplexed by the first communication station, based on arbitrary spreading factors;

assigning the spread data symbols to a specific subcarrier group only along a frequency axis for a single OFDM symbol interval, based on an OFDM method; and

multiplexing the spread data symbols to be transmitted to the second communication stations, which are assigned to the single subcarrier at the spreading and assignment steps, while performing hopping using only orthogonal codewords.

5. The OFCHM communication method according to claim 1, wherein the multiplexing comprises the steps of:

spreading data symbols, to be transmitted to the second communication stations and multiplexed by the first communication station, based on arbitrary spreading factors;

assigning the spread data symbols to a specific subcarrier group only along frequency axis for a single OFDM symbol interval, based on an OFDM method; and

multiplexing the spread data symbols to be transmitted to the second communication stations, which are assigned at the spreading and assignment stemps, while performing hopping on the data symbols using both orthogonal subcarriers and orthogonal codewords.

6. The OFCHM communication method according to claim 1, wherein the multiplexing comprises the steps of:

spreading data symbols, to be transmitted to the second communication stations and multiplexed by the first communication station, based on arbitrary spreading factors;

assigning the spread data symbols to a specific subcarrier group along both time and frequency axes for several OFDM symbol intervals, based on an OFDM method; and

multiplexing the spread data symbols to be transmitted the second communication stations, which are assigned at the spreading and assignment stemps, while performing hopping on the data symbols using only orthogonal codewords.

7. The OFCHM communication method according to claim 1, wherein the multiplexing comprises the steps of:

spreading data symbols, to be transmitted to the second communication stations and multiplexed by the first communication station, based on arbitrary spreading factors;

assigning the spread data symbols to a specific subcarrier group along time and frequency axes for several OFDM symbol intervals, based on an OFDM method; and

multiplexing the spread data symbols to be transmitted to the second communication stations, which are assigned at the spreading and assignment stemps, while performing hopping on the data symbols using both orthogonal subcarriers and orthogonal codewords.

8. The OFCHM communication method according to claim 1, wherein the multiplexing is performed in such a manner that arbitrary spreading factors used for spreading of data symbols to be transmitted to the second communication stations and multiplexed by the first communication station, and hopping among subcarriers and among orthogonal codewords, are adjusted depending on a channel environment between the first communication station and the second communication stations.

9. The OFCHM communication method according to claim 8, wherein the multiplexing is performed in such a manner that the arbitrary spreading factors and the hopping among subcarriers and among orthogonal codewords are adjusted depending on distances between the first communication station and the second communication stations.

10. The OFCHM communication method according to claim 9, further comprising the step of adjusting the spreading factors at a time of starting a call or a communication session in such a manner to increase the transmission rate using a small spreading factor for a second communication station located close to the first communication station, and reduce the effect of interference attributable to adjacent cells using large spreading factor values for a second communication station located far from the first communication station, thus maintaining stable communication quality.

11. The OFCHM communication method according to claim 8, wherein the multiplexing is performed in such a manner that the arbitrary spreading factors and the hopping between subcarriers and between and orthogonal codewords are adjusted according to relative velocities between the first communication station and the second communication stations.

12. The OFCHM communication method according to claim 11, further comprising the steps of adjusting communication at a time of starting a call or a communication session in such a manner to assign small spreading factors to a second communication station with low velocities in order to follow slow variations in a channel over a time axis, and to assign large spreading factors to a second communication station with high velocities in order to obtain a diversity gain for fast variations in a channel over a time axis.

13. The OFCHM communication method according to claim 8, wherein the multiplexing is performed in such a manner that the arbitrary spreading factors and the hopping among subcarriers and among orthogonal codewords are adjusted according to the number of multiple paths between the first communication station and the second communication stations.

14. The OFCHM communication method according to claim 13, further comprising the steps of adjusting communication at a time of starting a call or a communication session in such a manner to assign small spreading factors along a time axis to the second communication stations with a small number of multiple paths, to follow slow variations in a channel over a frequency axis, and to assign large spreading factors along frequency axis to the second communication stations with a large number of multiple paths in order to obtain a diversity gain for fast variations in a channel.

15. The OFCHM communication method according to claim 1, wherein the orthogonal resources are classified into the first orthogonal resource group for which assignment of the subcarriers and the orthogonal codewords, that is, orthogonal resources, are allocated in a dedicated manner, and the second orthogonal resource group for which assignment of the subcarriers and the orthogonal codewords, that is, orthogonal resources, are allocated in a hopping manner.

16. The OFCHM communication method according to claim 15, wherein, when multiplexing is performed by the first communication station, some of the data symbol streams to be transmitted to the second communication stations are multiplexed by allocating the first orthogonal resource group through the fixed assignment of orthogonal resources, and

the remaining data symbol streams to be transmitted to the second communication stations are multiplexed by allocating the second orthogonal resource group through the hopping of orthogonal resources.

17. The OFCHM communication method according to claim 16, wherein the first resource group is operated using a method of performing adaptive modulation and coding on the data symbols to be transmitted to the second communication stations while assigning resources in a fixed manner based on scheduling, and the second resource group is operated using a method of managing radio resources based on a power control method.

18. The OFCHM communication method according to claim 16, wherein, when multiplexing is performed on data symbol streams to be transmitted to arbitrary second communication stations, a radio resource management method of adaptively determining one of the two orthogonal resource groups in consideration of service quality required by each of the second communication stations at the time of starting a call or a communication session, is used.

19. The OFCHM communication method according to claim 18, wherein, when multiplexing is performed on data symbol streams to be transmitted to arbitrary second communication stations, a radio resource management method of determining one of the two orthogonal resource groups to be used, according to the transmission rate required by each of the second communication stations, is used.

20. The OFCHM communication method according to claim 19, wherein a radio resource management method of assigning the first resource group in a fixed allocation manner to data symbol streams to be transmitted to the second communication stations requesting high transmission rates, and assigning the second resource group in a hopping manner to data symbol streams to be transmitted to the second communication stations requesting low transmission rates.

21. The OFCHM communication method according to claim 18, wherein, when multiplexing is performed on data symbol streams to be transmitted to arbitrary second communication stations, a radio resource management method of determining one of the two orthogonal resource groups to be used, in consideration of distances between the first and second communication stations, is used.

22. The OFCHM communication method according to claim 21, wherein a radio resource management method of assigning the first resource group in a fixed manner to data symbol streams to be transmitted to the second communications stations, which are located close to the first communication station, and assigning the second resource group in a hopping mode to data symbol streams to be transmitted to second communication stations, which are located far from the first communication station, is used.

23. The OFCHM communication method according to claim 18, wherein, when multiplexing is performed on data symbol streams to be transmitted to arbitrary second communication stations, a radio resource management method of determining one of the two orthogonal resource groups to be used, according to the given delay requirement of data to be multiplexed, is used.

24. The OFCHM communication method according to claim 23, wherein a radio resource management method of assigning the first resource group in a fixed manner to the data symbol streams to be multiplexed when the data is not sensitive to delay jitters, and assigning the second resource group in a hopping manner to the data to be multiplexed when the data is sensitive to delay jitters, is used.

25. The OFCHM communication method according to claim 18, wherein, when multiplexing is performed on data symbol streams to be transmitted to arbitrary second communication stations, a radio resource management method of determining one of the two orthogonal resource groups to be used, according to the number of second communication stations that are active in a current communication system, is used.

26. The OFCHM communication method according to claim 25, wherein a radio resource management method of assigning the first resource group in a fixed manner to the data symbol streams to be multiplexed when the number of second communication stations that are actively communicating with the first station is small, and assigning the second resource group in a hopping manner to the data symbol streams to be multiplexed when the number of second communication stations that is communicating with the first system is large, is used.

27. The OFCHM communication method according to claim 18, wherein, when multiplexing is performed on data symbol streams of arbitrary second communication stations, a radio resource management method of determining one of the two orthogonal resource groups to be used, according to the required bit error probability of data symbol streams to be multiplexed, is used.

28. The OFCHM communication method according to claim 27, wherein, when multiplexing is performed on data symbol streams of arbitrary second communication stations, determination of one of the two orthogonal resource groups to be used, is made using a radio resource management method of assigning the first resource group to data symbol streams to be transmitted to the second communication stations when the required bit error probability of data symbol streams to be transmitted is low, and assigning the second resource group to the data symbol streams to be transmitted to the second communication stations when the required bit error probability of data symbol streams to be multiplexed is high.

29. The OFCHM communication method according to claim 17, wherein a radio resource management method of assigning the first resource group based on scheduling in frequency band to the data symbol streams to be transmitted to the second communication stations, each of which has the small average value of channel states for an entire frequency band from the first communication station (a channel state in which path loss and shadow fading values are considered), and assigning the second resource group in a hopping manner to the data symbol streams to be transmitted to the second communication stations, each of which has large average values of frequency selective fading channels from the first communication station, is used.

30. The OFCHM communication method according to claim 29, wherein a radio resource management method of assigning the first resource group based on scheduling to the data symbol streams to be transmitted to all the second communication stations with a higher priority to a second communication station, which has the smallest average value of frequency selective fading channel (a channel state in which path loss, shadow fading, and frequency selective fading characteristic attributable to multiple path fading are considered).

31. The OFCHM communication method according to claim 29, wherein a radio resource management method of assigning the first resource group based on scheduling to the data symbol streams to be transmitted to all the second communication stations with a higher priority to a second communication station, which has the largest average value of frequency selective fading channel (a channel state in which path loss, shadow fading, and frequency selective fading characteristic depending on multiple path fading are considered).

32. The OFCHM communication method according to claim 29, wherein a radio resource management method of assigning the first resource group based on scheduling to the data symbol streams to be transmitted to all the second communication stations with a higher priority to a second communication station, which has the smallest maximum value of frequency selective fading channels (a channel state in which path loss, shadow fading, and frequency selective fading characteristic depending on multiple path fading are considered).

33. The OFCHM communication method according to claim 29, wherein the first resource group based on scheduling is assigned to the data symbol streams to be transmitted to all the second communication stations, and one or more subcarriers assigned by the first communication station for communication are bound into one subcarrier group and managed, and an identical adaptive modulation and coding method is employed within the group.

34. The OFCHM communication method according to claim 33, wherein the first resource group based on scheduling is assigned to the data symbol streams to be transmitted to all the second communication stations, and the average, maximum, minimum, and harmonic values of channel states of a frequency subcarrier group, which is bound according to frequency range spreading factors to be assigned to the second communication stations, are used in determining a representative value of frequency selective fading channels, in order to schedule a frequency range of the subcarrier group assigned by the first communication station for communication.

35. The OFCHM communication method according to claim 34, wherein, when an adaptive modulation and coding method is applied to the subcarrier group assigned to each of the second communication stations, the average, maximum, minimum, and harmonic values of channel states of a frequency subcarrier group, which is bound according to frequency range spreading factors to be assigned to the second communication stations, are used in determining a representative value of frequency selective fading channels of the subcarrier group.

36. The OFCHM communication method according to claim 1, wherein beamforming is made for individual data streams multiplexed by the first communication station using multiple array antennas according to the locations of the second communication stations.

37. The OFCHM communication method according to claim 36, wherein, when a transmission beamforming is made using multiple array antennas, a beamforming region to which a specific second communication station belongs is selected among fixed transmission beamforming regions previously defined in consideration of information about locations of the second communication stations, and a beam for a corresponding transmission data streams is formed.

38. The OFCHM communication method according to claim 36, wherein, when a transmission beamforming is made using multiple array antennas, a dynamic beamforming is made to provide an antenna gain for a corresponding transmission data streams in consideration of information about the locations of the second communication stations.

39. The OFCHM communication method according to claim 2, wherein transmission beamforming is made for the individual data streams multiplexed by the first communication station using multiple array antennas according to the locations of the second communication stations.

40. The OFCHM communication method according to claim 39, wherein, when a transmission beamforming is made using multiple array antennas, a beamforming region to which a specific second communication station belongs is selected among fixed transmission beamforming regions previously defined in consideration of information about the locations of the second communication stations, and a beam for a corresponding transmission data streams is formed.

41. The OFCHM communication method according to claim 39, wherein, when a transmission beamforming is made using multiple array antennas, a dynamic beamforming is made to provide an antenna gain for a corresponding transmission data streams in consideration of information about the locations of the second communication stations.

42. The OFCHM communication method according to claim 8, wherein the spreading factors used for spreading the data streams and hopping among the subcarriers and orthogonal codewords are adjusted in consideration of distribution of transmission beams formed for individual data streams as well as varying channel environments between the first communication station and the second communication stations.