Wireless simulator

• US 20030236089A1
• Filed: 02/14/2003
• Published: 12/25/2003
• Est. Priority Date: 02/15/2002
• Status: Active Grant

• Current Assignee: Viavi Solutions, Inc. (Lumentum Holdings Inc.)
• Original Assignee: Dyaptive Systems, Inc. (Lumentum Holdings Inc.)
• Inventors: Sankey, Todd, Beyme, Steffen, Kilgour, Chris
• Granted Patent: US 7,286,802 B2
• Time in Patent Office: Days
• US Class Current: 455/423
• CPC Class Codes: H04B 17/0087 using auxiliary channels or channel simulators
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 52/04 TPC
• CPC Class Codes: H04W 52/60 using different transmission rates for TPC commands

Abstract

There is disclosed a simulator for mobile terminals within the context of a wireless network, for the purpose of testing the basestations. Channel impairments are effected during baseband processing.

Claims

1. A system to simulate part of a cellular network comprising:

(a) means for simulating a plurality of MTs [SMTs];

(b) means for providing the functions of a first basestation [network access point/equivalent];

(c) means for simulating a communications forward link between said first basestation and each of said plurality of said SMTs through individual channels therebetween;

with both said simulating means are implemented on a generic, communications protocol-agnostic SDR hardware platform.

2. The system of claim 1, further comprising means for simulating a communications reverse link between each of said plurality of SMTs through individual channels therebetween.

3. The system of claim 1 or 2, wherein said simulated forward link is effected by simulating the effects of impairments to each said channel as presented to the receiving portion of each said SMT.

4. The system of claim 1, 2 or 3, wherein said simulated reverse link is effected by simulating the effects of impairments to each said channel as presented to the transmitting portion of each said SMT.

5. The system of claims 1 to 4, wherein said basestation means includes a real basestation.

7. The system of claims 1 to 6, wherein signals transmitted on two of said channels operate on different communications protocols.

8. The system of claims 1 to 7, wherein signals transmitted on two of said channels are the subject of different encoding and decoding methods.

9. The system of claims 1 to 8, wherein signals transmitted on two of said channels are carried on different frequencies.

10. The system of claims 1 to 9, wherein two of said channels have different bandwidths.

11. The system of claims 1 to 10, wherein said channel simulation is effected by the application of an impairment of said forward link or said reverse link of one said channels.

12. The system of claims 1 to 11, wherein said channel impairment includes the simulation of movement of at least one said SMT.

13. The system of claims 1 to 12, wherein said channel impairments reflect features of the physical environment.

14. The system of claims 1 to 13, wherein said channel impairment includes the simulation of one of, for each SMT-sector combination, (a) mean path loss (MPL), (b) large-scale fading loss, (c) small-scale fading loss, and (d) lumped-parameter phase rotation.

15. The system of claim 14, wherein MPL is defined by configuration parameters and real-time parameters.

16. The system of claim 15, wherein MPL configuration parameters include one of:

SMT antenna gain, SMT instantaneous band class, SMT instantaneous carrier frequency, and the applicable MT Class.

17. The system of claim 16, wherein MPL real-time parameters include one of:

BTS sector antenna gain, BTS-SMT line of sight distance, BTS sector raw pilot strength(s) and BTS sector raw output power.

18. The system of claim 14, wherein small-scale fading is due to propagation impairments that are small compared to the carrier wavelength to introduce effects like multipath and Doppler.

19. The system of claims 1-18, further comprising means for providing the functions of a second basestation and further comprising means for simulating two-way communications between said second basestation function means, and one of said plurality of SMTs.

20. The system of claims 1-19, further comprising means for coordinating/controlling said first and second basestation function means.

21. The system of claims 1-19, where one of the protocols is one of FDMA, CDMA or derivatives thereof.

22. The system of claims 1-21, wherein said forward link channel includes the following sequential steps:

(a) Processing RF to digital baseband

(b) Processing digital baseband to chip

(c) Processing chips to symbols

(I) Sector scaling and combining

(II) Chip-rate Channel simulation

(III) Power-control rate channel simulation

(d) Processing symbols to frames

23. The system of claims 1-22, wherein said reverse link channel includes the following sequential steps:

(a) Processing frames to symbols

(b) Processing symbols to chips

(c) Channel simulation, sector scaling and combining

(I) Channel simulation

(II) Combined power control and channel simulation

(III) Sector scaling and combining

(d) Processing chips to RF

24. The system of claims 1-23, wherein a channel profile is created to be a time-varying vector of channel simulation parameters.

25. The system of claims 1-24, wherein a channel simulation parameters include those for simple and complex fading.

26. The system of claims 1-25, wherein channel simulation parameters are created on a per-SMT and per BTS sector basis.

27. The system of claims 1-26, wherein static channel simulation parameters include one of the following:

calibrated transceiver conversion gain and connection loss between each BTS sector and the MTS.

28. The system of claims 1-27, wherein for each SMT-sector combination, channel simulation includes one of:

(a) mean path loss (MPL), (b) large-scale fading loss, (c) small-scale fading loss, and (d) lumped-parameter phase rotation.

29. The system of claims 1-28, wherein MPL is defined by configuration parameters and real-time parameters.

33. The system of claim 1-32, further comprising scenario/channel simulation engine engine for creating a real time simulation of a plurality of SMTs interacting with said fisrt basestation.

34. The system of claim 33, comprising means for defining a script of channel impairments for said scenario/channel simulation engine.

35. The system of claim 34, further comprising means for assigning said defined script to a SMT/MTS.

36. The system of claim 35, further comprising means for activating said assigned script.

37. The system of claim 36, whwerin groups of SMTs are scripted to perform similarly.

38. The system of claims 1-37, further comprising means for interfacing with test equipment.

39. The system of claims 1-37, comprising means for interfacing with a PC.

40. The system of claims 1-39, further comprising an antenna and said MTS is connected to said antenna

41. The system of claims 1-40, wherein said simulation includes the sharing of functions and processing steps of SMTs during baseband processing.

42. The system of claims 1-41, wherin said simulation is effected by simulating all RF paths between said besestation and a plurality of SMTs, by combining and scaling all individual RF carriers.

43. The system of claim 42, wherein said first basestation functions are sectorized, and where in the forward direction, the received signals R at an SMT is the product of gian G and sector signals S, where G is adjusted to reflect attenuations/impairments (e.g. time varying propagation paths) in the RF domain.

44. The system of claim of 43, where in said forward link, said channel simulation includes mathematically approximating channel impaiments.

45. The system of claim 43, wherein said approximating is done by sampling at granularity of chip-rate.

46. The system of claim 43, wherein said approximating is done by sampling at granularity of power control rate.

47. The system of claim 43, wherein said approximately is done by sampling at granularity of frames or groups of symbols.

48. The system of claim 44-47 wherein approximating is done by sampling at power control reate for one channel and chip rate simulation for another channel.

49. The system of claims 1-48, where in said forward link, said channel simulation includes scaling of the energy contribution of each basestation sector and the interference levels.

50. The system of claims 1-49, wherein said reverse link, said channel simulation includes calculating elements of one of said communications protocols (e.g. the desired pilot strength Ec/Io at each SMT being calculated once and sent to all SMTS (instead of being measured by each SMT).

51. The system of claim 50, where the calculation is by appropriate sector scaling G.

52. The system of claim 51, wherein in said reverse link, said channel simulation combines power control and channel simulation (G'"'"'=G×

R/R0) where R=KR0.

53. The system of claims 1-52, where all demodulation and decoding of shared channels (e.g. paging channels) for all SMTS is done by a single, shared hardware/firmware resource.

54. The system of claim 53, where in the distribution of symbols in all SMTS is only indirectly simulated at BER, and where relatives sector power (pilot strength) does not actually change when simulating soft(er) handoff.

57. The system of claim 56, wherein said SMT simulation means (claim 1(a)) includes a software/hardware cradle for histing a SMT=a MT simulator [MTS]

58. The system of claim 57 further comprising controller means, in a communications link with said MTS, for instantiating a SMT in said MTS.

59. The system of claim 58, where said MTS is directly connected to BTS sector ports

60. The system of claim 59, where if BTS has n sectors, a MTS has atleast n+1 connections.

61. The system of claims 1-60, wherein said SMT state information includes information necessary for it to operate within an MTS

62. The system of claim 61, wherein said communications link between said MTS and said controller has a throughput capability greater than that in a typical MT/BTS communications.

63. The system of claim 61, wherein said controller can send “

override”

commands to the SMT/MTS, for creating conditions that are abnormalfor an MT.

64. The system of claims 1-63, wherein said mobility simulation is effected by providing the functions of a second basestation, and said two basestations wherein said (forward and reverse) channel simulations and pilot management are performed to effect a soft handoff.

65. The system of claims 1-64, wherein said MTS is in direct communication with said basestations.

66. The system of claims 1-64, comprising a plurality of MTSs and a plurality of base stations, wherein each said MTS is in direct communication with at least two of said basestations, and where mobility simulation is effected by moving one said SMT from one said MTS to a second said MTS. [e.g. by instantiating the SMT in the second MTS by copying state information frm first MTS to second MTS].

67. The methods for carrying out the claims 1-66.

6. The system of claims Ito 4, wherein said basestation means further includes means for simulating portions of a real basestation.

30. The system of claim, wherein MPL configuration parameters include:

SMT antenna gain, SMT instantaneous band class, SMT instantaneous carrier frequency, and the applicable MT Class).

31. The system of claim, wherein MPL real-time parameters include:

BTS sector antenna gain, BTS-SMT line of sight distance, BTS sector raw pilot strength(s) and BTS sector raw output power.

32. The system of claim 31, wherein small-scale fading is due to propagation impairments that are small compared to the carrier wavelength and introduce effects like multipath and Doppler.

55. The system of 54, whwere reverse link combining of the baseband transmit signals of a plurality of SMTS operating on the same carrier, and subsequent filtering of the signal sum digital upconversion to IF.

56. The system of claim 56, wherein combination/accumulation is distriduted among the individual SMTS and they are connected by a multiplex bus or tree.