CA2400934A1 - Reverse link correlation filter in wireless communication systems - Google Patents

Reverse link correlation filter in wireless communication systems Download PDF

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Publication number
CA2400934A1
CA2400934A1 CA002400934A CA2400934A CA2400934A1 CA 2400934 A1 CA2400934 A1 CA 2400934A1 CA 002400934 A CA002400934 A CA 002400934A CA 2400934 A CA2400934 A CA 2400934A CA 2400934 A1 CA2400934 A1 CA 2400934A1
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Prior art keywords
information
correlation filter
processor
gate array
pilot
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CA002400934A
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French (fr)
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CA2400934C (en
Inventor
Antoine J. Rouphael
John E. Hoffmann
George Rodney Nelson Jr.
Samir K. Patel
James A. Proctor, Jr.
Daniel I. Riley
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IPR Licensing Inc
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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7097—Interference-related aspects
    • H04B1/7103—Interference-related aspects the interference being multiple access interference
    • H04B1/7105—Joint detection techniques, e.g. linear detectors
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/69—Spread spectrum techniques
    • H04B1/707—Spread spectrum techniques using direct sequence modulation
    • H04B1/7097—Interference-related aspects
    • H04B1/711—Interference-related aspects the interference being multi-path interference
    • H04B1/7115—Constructive combining of multi-path signals, i.e. RAKE receivers
    • H04B1/712—Weighting of fingers for combining, e.g. amplitude control or phase rotation using an inner loop
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
    • H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
    • H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
    • H04B2201/70703—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation using multiple or variable rates
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
    • H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
    • H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
    • H04B2201/70703—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation using multiple or variable rates
    • H04B2201/70705—Rate detection
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B2201/00—Indexing scheme relating to details of transmission systems not covered by a single group of H04B3/00 - H04B13/00
    • H04B2201/69—Orthogonal indexing scheme relating to spread spectrum techniques in general
    • H04B2201/707—Orthogonal indexing scheme relating to spread spectrum techniques in general relating to direct sequence modulation
    • H04B2201/70707—Efficiency-related aspects
    • H04B2201/7071—Efficiency-related aspects with dynamic control of receiver resources

Abstract

A single, common correlation filter (CF) core is provided in a wireless syst em using CDMA (code division multiple access). A plurality of channels with different data rates are provided in the wireless system. The channels provided in the wireless system include the access channel, the maintenance channel, and the traffic channel in which information (e.g., pilot or data symbols or both) is transmitted at the tier 1 (which is the basic despreadin g rate), tier 2 and tier 3 rates. The data rate for transmitting the informati on is programmable by an external programmable processor, e.g., a digital signa l processor (DSP). A user-unique code, such as a PN (pseudo-random noise) code , is applied to the information being transmitted in the channels of the wireless system. Theinformation is modulated and transmitted in any one of t he channels at any data rate. The transmitted information is correlated at the basic despreading rate (i.e., the tier 1 rate) in the correlation filter (CF ) of the wireless system by time multiplexing delayed versions of the PN code (or orthogonal code, Walsh code) to the correlation filter core. The correlated information is then demultiplexed and demodulated. The demodulate d information is summed at the proper integer multiple of the tier 1 rate to achieve the tier 2 and tier 3 rates. One or more signal components are selected (in terms of the received power, signal-to-noise ratio or multipath width) in a window or time period for optimal information recovery. The selecting step can also be implemented according to a preprogrammed time alignment. Furthermore, outputs from the demodulated information can be provided and combined for temporal diversity. Spatial diversity is achieved by providing a plurality of antennas, and a plurality of receivers at a locatio n and providing a single, common correlation filter at each of the plurality o f antennas of the receivers in the wireless system.

Claims (54)

1. In a code division multiple access (CDMA) communications system having a plurality of channels with different data rates, a method comprising the steps of:

applying a user-unique code to information being transmitted in the channels;

modulating the information;

correlating the transmitted information at a basic despreading rate using time multiplexing in a single correlation filter;

demultiplexing the correlated information;

demodulating the correlated information; and summing the demodulated information at a rate greater than or equal to the basic despreading rate to obtain information at other data rates of the different data rates.
2. The method of claim 1 wherein the user-unique code is pseudorandom noise (PN) code.
3. The method of claim 1 wherein the user-unique code is orthogonal code.
4. The method of claim 1 wherein the user-unique code is Walsh code.
5. The method of claim 1 wherein the modulating and demodulating steps are performed using QPSK (quadrature phase shift keying).
6. The method of claim 1 wherein the information in any one of the channels consists of pilot symbols and data symbols interleaved in a specified and known order.
7. The method of claim 1 further comprising the step of:

after the summing step, selecting one or more signal components in terms of received power based on a channel estimate from pilot symbols inserted into a waveform of the transmitted information.
8. The method of claim 1 further comprising the step of:

after the summing step, selecting one or more signal components in terms of signal-to-noise ratio based on a channel estimate from pilot symbols inserted into a waveform of the transmitted information.
9. The method of claim 1 further comprising the step of:

after the summing step, selecting one or more signal components in terms of multipath width based on a channel estimate from pilot symbols inserted into a waveform of the transmitted information.
10. The method of claim 1 further comprising the step of:

after the summing step, selecting one or more signal components according to a preprogrammed time alignment.
11. The method of claim 1 in which temporal diversity is provided by causing the demodulated step to provide two or more outputs of demodulated information and combining the outputs into one output.
12. The method of claim 11 wherein the outputs are combined into one output using maximum ratio combining (MRC).
13. The method of claim 1 wherein the channels comprise of an access channel, a maintenance channel, and a traffic channel.
14. The method of claim 1 wherein the basic despreading rate is 8 chips per symbol.
15. The method of claim 1 wherein the basic despreading rate is 4 chips per symbol.
16. The method of claim 1 wherein any one of the steps of the applying, correlating, demodulating and summing steps is programmable by an external programmable processor.
17. The method of claim 1 wherein any one of the steps of the applying, modulating, transmitting, correlating, demodulating and summing steps is performed in a traffic channel.
18. The method of claim 1 wherein any one of the steps of the applying, modulating, transmitting, correlating, demodulating and summing steps is performed in an access channel.
19. The method of claim 1 wherein any one of the steps of the applying, modulating, transmitting, correlating, demodulating and summing steps is performed in a maintenance channel.
20. The method of claim 1 in which spatial diversity is provided by providing multiple antennas, multiple receivers at a location and providing the same, single correlation filter at each of the plurality of receivers of the system.
21. The method of claim 1 further comprising the steps of:

(a) after the summing step, selecting a most desired signal component in terms of received power of a multipath response in a time period;

(b) storing a magnitude of the most desired signal component;

(c) setting a first blank-out region of the most desired signal component defined by a first upper limit and a first lower limit;

(d) selecting a second most desired signal component of the multipath response in the time period by ignoring the first blank-out region;

(e) setting a second blank-out region of the second most desired signal component defined by a second upper limit and a second lower limit; and repeating steps (a), (b), (c), (d) and (e) until the Nth most desired signal component is selected.
22. The method of claim 21 wherein the selecting in steps (a) and (d) are performed in terms of signal-to-noise ratio based on a channel estimate from pilot symbols inserted into a waveform of the transmitted information.
23. The method of claim 21 wherein the selecting in steps (a) and (d) are performed in terms of multipath width based on a channel estimate from pilot symbols inserted into a waveform of the transmitted information.
24. The method of claim 21 wherein the selecting in steps (a) and (d) are performed according to a preprogrammed time alignment.
25. The method of claim 21 further comprising the steps of:

setting 1 through N blanc-out regions respectively defined by 1 through N upper limits and 1 through N lower limits; and summing all power elements of the multipath response in the time period for noise power estimation, while ignoring all of the blank-out regions.
26. The method of claim 21 wherein the lower and upper limits of each signal component are programmed by an external programmable processor.
27. A code division multiple access (CDMA) communications system having a plurality of channels with different data rates, the system comprising:

a transmitter applying a user-unique code to data and pilot signal information being transmitted in the channels and modulating the information;
and a receiver comprising a gate array and an external programmable processor, the gate array further comprising (a) a code generator generating the user unique code, (b) a correlation filter having a single, common correlation filter core operable with all of the channels with different data rates, said correlation filter core correlating the transmitted information at a basic despreading rate, (c) a multiplexer for directing to the correlation filter, on a time multiplexed basis, delayed phase versions of the user-unique code, (d) a gate array data post processor for receiving the output of the correlation filter and demodulating it to recover the transmitted data signals, (e) and a gate array pilot post processor for receiving the output of the correlation filter and processing it to recover pilot signals, and the external programmable processor further comprising (a) a mode controller connected to the code generator, correlation filter, multiplexer, data post processor and pilot post processor for controlling channel selection in the system, (b) an external programmable data post processor for receiving and processing signals from the gate array data post processor and the external programmable data post processor, and (c) an external programmable pilot post processor for receiving and processing signals from the gate array pilot post processor, said external programmable data and pilot post processors summing the demodulated information at a multiple of the basic despreading rate to obtain information at other data rates of the different data rates.
28. The system of claim 27 wherein the user-unique code is pseudorandom noise (PN) code.
29. The system of claim 27 wherein the user-unique code is an orthogonal code.
30. The system of claim 27 wherein the user-unique code is a Walsh code.
31. The system of claim 27 wherein the information in any one of the channels consists of pilot symbols and data symbols interleaved in a specified and known order.
32. The system of claim 27 wherein one or more desired signal components in terms of received power are selected at the external programmable processor fox data processing.
33. The system of claim 27 wherein temporal diversity is achieved by providing two or more outputs as demodulated information from the correlation filter and combining the outputs into one output in the external programmable data and pilot post processors by use of maximum ratio combining (MRC).
34. The system of claim 27 wherein the channels consist of an access channel, a maintenance channel, and a traffic channel.
35. The system of claim 27 wherein the basic despreading rate is 8 chips per symbol.
36. The system of claim 27 wherein the basic despreading rate is 4 chips per symbol.
37. The system of claim 27 wherein the correlation filter (CF) core is programmable by the mode controller of the external programmable processor.
38. The system of claim 27 wherein the correlation of the transmitted information is programmable by the external programmable processor.
39. The system of claim 27 wherein spatial diversity is achieved by providing multiple antennas, multiple receivers at a location and providing the same, single common correlation filter at each of the plurality of antennas of the receivers in the system.
40. In a code division multiple access (CDMA) communications system having a plurality of channels including an access channel, a maintenance channel and a traffic channel with different data rates, the system comprising:
a transmitter applying a user-unique code to pilot symbol and data symbol information and modulating the information; and a receiver comprising a gate array and an external programmable processor, the gate array further comprising (a) a code generator generating the user unique code, (b) a correlation filter having a single, common correlation filter core operable with all of the channels with different data rates, said correlation filter core correlating the information at a basic despreading rate, (c) a multiplexer for directing to the correlation filter, on a time multiplexed basis, delayed phase versions of the user-unique code, (d) a gate array data post processor for receiving the output of the correlation filter and demodulating it to recover the transmitted data signals, (e) and a gate array pilot post processor for receiving the output of the correlation filter and processing it to recover pilot,and the digital signal processor further comprising (a) a mode controller connected to the code generator, correlation filter, multiplexer, data post processor and pilot post processor for controlling channel selection in the system, (b) an external programmable data post processor for receiving and processing signals from the gate array data post processor and the external programmable data post processor, and (c) an external programmable pilot post processor for receiving and processing signals from the gate array pilot post processor, said external programmable data and pilot post processor s summing the demodulated information at a multiple of the basic despreading rate to obtain information at other data rates of the different data rates;
and wherein said correlation filter core correlates the pilot and data symbols at the basic despreading rate using time multiplexing in said received signal;

said gate array demodulates and recovers the data symbols according to the correlated pilot symbols; and said external programmable processor sums the demodulated information at a rate greater than or equal to the basic despreading rate to obtain desired data symbols.
41. The system of claim 40, said gate array further comprising a time multiplexes for directing user unique codes to the correlation filter core and a time demultiplexer for receiving the output of the correlation filter core.
42. The system of claim 40 wherein said correlation filter core is an 8-chip complex correlation engine which produces the basic despreading rate of 8 chips per symbol.
43 . The system of claim 40 wherein said correlation filter core is a 4-chip complex correlation engine which produces the basic despreading rate of 4 chips per symbol.
44. The system of claim 43, said gate array further comprising a window processor receiving the output of the correlation filter core and producing a phase-compensated output using a complex multiplier for all correlation lags for each 4-chip symbol.
45. The system of claim 42, said gate array further comprising a window processor receiving the output of the correlation filter core and producing a phase-compensated output using a complex multiplier for all correlation lags for each 8-chip symbol.
46. The system of claim 40 wherein said gate array pilot post processor further comprises two accumulating filter random access memories (AFRAMs) having an infinite impulse response (IIR) filter, the AFRAMs functionally serving as memory, accumulator and filter and wherein the filter coefficients of the AFRAMs are programmable by the external programmable processor.
47. The system of claim 40 wherein said gate array pilot post processor further comprises a magnitude accumulating filter random access memory (MAFRAM) serving as a memory, accumulator and a filter for magnitude squared data from the accumulating filter random access memories (AFRAMs), and wherein the IIR
filter coefficients of the MAFRAM are programmable by the external programmable processor.
48. The system of claim 40, said gate array pilot post processing further comprising multipath search processing which is programmable by the external programmable processor, wherein the multipath search process searches for the one or more signal components in terms of received power in a time period.
49. The system of claim 40, said gate array pilot post processing further comprising multipath search processing which is programmable by the external programmable processor, wherein the multipath search process searches for the one or more signal components in terms of signal-to-noise ratio in a time period.
50. The system of claim 40, said gate array pilot post processing further comprising multipath search processing which is programmable by the external programmable processor, wherein the multipath search process searches for the one or more signal components in terms of multipath width in a time period.
51. The system of claim 40, said gate array pilot post processing further comprising multipath search processing which is programmable by the external programmable processor, wherein the multipath search process searches for the one or more signal components according to a preprogrammed time alignment.
52. The system of claim 48 wherein said external programmable data post processor uses maximum ratio combining (MRC) to achieve temporal diversity according to the two or more signal components found by the multipath search processing of said gate array.
53. The system of claim 40 wherein spatial diversity is achieved by providing a plurality of antennas, and a plurality of receivers at a location and providing the same, single correlation filter design at each of the plurality of antennas of the receivers of the system.
54. The system of claim 45, said gate array data post processor further comprises symbol processors summing programmable sections of correlation delay and forming two or more outputs, wherein said external programmable processor combines the outputs into one output to achieve temporal diversity.
CA2400934A 2000-02-23 2001-02-23 Reverse link correlation filter in wireless communication systems Expired - Fee Related CA2400934C (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
US18436400P 2000-02-23 2000-02-23
US60/184,364 2000-02-23
US09/738,934 2000-12-15
US09/738,934 US6801564B2 (en) 2000-02-23 2000-12-15 Reverse link correlation filter in wireless communication systems
PCT/US2001/005682 WO2001063778A2 (en) 2000-02-23 2001-02-23 Reverse link correlation filter in multi rate cdma wireless communication systems

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CA2400934A1 true CA2400934A1 (en) 2001-08-30
CA2400934C CA2400934C (en) 2011-04-05

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US (3) US6801564B2 (en)
EP (3) EP1686697B8 (en)
JP (1) JP2004500768A (en)
KR (4) KR100972804B1 (en)
CN (1) CN1227828C (en)
AT (2) ATE323344T1 (en)
AU (1) AU2001238632A1 (en)
CA (1) CA2400934C (en)
DE (2) DE60138496D1 (en)
DK (1) DK1269646T3 (en)
HK (1) HK1052802B (en)
WO (1) WO2001063778A2 (en)

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