Method and apparatus for high-speed software reconfigurable code division multiple access communication

• US 7,327,779 B1
• Filed: 07/19/2000
• Issued: 02/05/2008
• Est. Priority Date: 07/23/1999
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Vanhoof, Jan, Borghs, Eric, Lugil, Nico, Philips, Lieven, Vandermot, Jurgen, Louveaux, Sébastien, Mertens, Carl
• Primary Examiner(s): BURD, KEVIN MICHAEL
• Application Number:
  US10/048,142
• Time in Patent Office: 2,757 Days
• Field of Search: 375/130, 375/140, 375/141, 375/146, 375/147, 375/219
• US Class Current: 375/141
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 2201/7071 with dynamic control of receiver resources

Abstract

A communication device for W-CDMA signal transmission and reception includes a W-CDMA transmitter having at least one of a RAM and registers, a W-CDMA receiver having at least one of a RAM and registers, and a signal acquisition circuit. The communication device is software reconfigurable and further includes a digital circuit for phase unbalance precompensation in the W-CDMA transmitter. The digital circuit includes an input register holding a compensation angle and a section performing arithmetic calculations to acquire a change of an I, Q angle by the compensation angle. A method of operating a W-CDMA communication device includes the acts of configuring the device for a specific use, and performing at least one of transmitting, receiving and acquiring waveform signals. The configuring is preferably done by a processor.

Claims

1. A communication device for W-CDMA signal transmission and reception, which is software configurable, comprising:

a W-CDMA transmitter comprising at least one of a RAM and registers;

a W-CDMA receiver comprising at least one of a RAM and registers;

a signal acquisition circuit; and

a digital circuit for phase unbalance precompensation in said W-CDMA transmitter, wherein said digital circuit substantially removes the I, Q phase difference that causes the phases to not have a 90 degree separation,

wherein the receiver comprises;

a pulse shaping filter;

an level control block;

a demodulator assigned to track multi-path components received from one base station; and

a reference demodulator for S/(N+1) measurements,

wherein the level control block comprises;

a programmable shifter to perform coarse grain dynamic control;

a programmable multiplier to perform fine grain dynamic control;

an overflow counter operating on a most significant bit and a second most significant bit; and

a saturation logic to clip a result from the multiplier.

2. The communication device of claim 1, further comprising a circuit for noise and interference estimation, said circuit comprising:

means to acquire a programmable number of absolute value accumulations at a chip rate or an oversampled chip rate; and

a programmable low pass filter to average the noise and interference estimations.

3. The communication device of claim 1, further comprising a circuit for initial synchronization, said circuit comprising:

a matched filter, energy calculation and accumulating RAM for slot synchronization;

a set of correlators for frame synchronization and code group identification;

an energy estimation block; and

maximum detection means readable by a microprocessor subsystem.

4. The communication device of claim 3, wherein the communication device is configured for at least one of waveform transmission, reception and acquisition of signals selected from the group consisting of UMTS, Satellite UMTS, Galileo, GPS, IS-2000, IMT-2000, CDMA2000, IS-95, 3GPP, 3GPP2 and ARIB signals.

5. The communication device of claim 1, further comprising circuitry to generate packet data transmission, said circuitry comprising:

a buffer storing data and activity bits;

I, Q spreaders and gain control means;

scrambling code generator and scrambling means; and

means for packet timing through RX frame edge triggering.

6. The communication device of claim 5, wherein the communication device is configured for RACH transmission in UMTS/FDD.

7. The communication device of claim 1, further comprising a processor.

8. The communication device of claim 7, wherein the processor is configured to reconfigure the communication device.

9. The communication device of claim 7, wherein the processor controls at least one of the RAM registers of said W-CDMA signal transmitter and receiver.

10. The communication device of claim 7, wherein the transmitter comprises a first programmable pulse shaping filter, and wherein the receiver comprises a second programmable pulse shaping filter.

11. The communication device of claim 10, wherein the pulse shaping filters are programmable to perform GMSK filtering, and wherein said transmitter and receiver are arranged to interface with a GSM front-end.

12. The communication device of claim 11, wherein the processor performs a GSM protocol stack.

13. The communication device of claim 1, wherein said transmitter comprises one or more elements selected from the group consisting of:

synchronization hardware to slave transmit start epochs to events external to the transmitter;

a burst generator for realizing discontinuous transmissions;

a QPN channel containing one or more spreaders with their own amplification of the output;

a combiner to accumulate the QPN channel output;

a PN code generator;

a scrambling code generator;

a scrambler;

a combiner which accumulates the scrambling code output;

a pulse shaping oversampling filter; and

an NCO and upconverter for carrier precompensation.

14. The communication device of claim 13, wherein the PN code generator is realized as a RAM in which PN codes are downloaded under control of the processor.

15. The communication device of claim 13, wherein the scrambling code generator is realized as a programmable Gold Code generator.

16. The communication device of claim 13, wherein the QPN channel is arranged to execute UMTS forward or return link transmission.

17. The communication device of claim 13, wherein an amplification of the spreader output is arranged to perform transmit power control.

18. The communication device of claim 1, wherein the transmitter comprises a time interpolator to perform sub-chip time alignments.

19. The communication device of claim 1, wherein the transmitter is arranged for multi-code transmission.

20. The communication device of claim 1, wherein said receiver further comprises a downconverter prior to said pulse shaping filter in order to interface at a front-end at an intermediate frequency.

21. The communication device of claim 1, wherein the receiver is arranged for execution of at least one of UMTS, Satellite UMTS, Galileo, GPS, IS-2000, IMT-2000, CDMA2000, IS-95, 3GPP, 3GPP2 and ARIB forward link and return link waveforms.

22. The communication device of claim 1, wherein the level control block is operated in a runtime control loop by the processor.

23. The communication device of claim 1, wherein the demodulator comprises:

a Rake filter producing a signal at a chip rate which is a coherent accumulation of channel corrected multipath components resulting from one base station;

a tracking unit using said signal at the chip rate for descrambling and despreading a plurality of waveform channels;

in which said Rake filter comprises;

a FIFO to buffer samples at chip rate coming from said level control block;

a delay line containing a plurality of registers, an input of the delay line being connected to an output of said FIFO;

a plurality of finger blocks, inputs of said finger blocks being connected to programmable tap positions on said delay line; and

a summator of complex outputs of said finger blocks at chip rate.

24. The communication device of claim 23, wherein the finger blocks are respectively grouped in a late multipath group and an early multipath group, the Rake filter being arranged to accumulate the energies of the outputs of said late multipath group and said early multipath group, and to use these accumulated values to feed the time error detector of the DLL for time tracking.

25. The communication device of claim 23, wherein the Rake filter comprises memories to hold at least one of a spreading code for a channel correction Pilot, a scrambling code for a channel correction Pilot, a channel correction Pilot symbol modulation, and a channel correction Pilot symbol activities.

26. The communication device of claim 25, wherein the memories are controlled by the processor.

27. The communication device of claim 25, wherein the finger block comprises:

a channel correction Pilot descrambler;

a channel correction Pilot despreader;

a channel correction Pilot filter, first performing a coherent channel correction Pilot symbol accumulation over a programmable number of steps, and secondly producing a weighted average on a programmable number of said coherent channel correction Pilot symbol accumulation over a programmable number of steps;

a channel estimator generating a channel estimation at chip rate, using outputs of said Pilot filter;

a channel corrector performing a multiplication of an incoming chip stream with a complex conjugate of said channel estimation;

a calculation of a slot energy;

a comparison of the slot energy with a programmable threshold; and

a circuit to force said channel estimation to zero if said threshold is not exceeded.

28. The communication device of claim 27, wherein the finger is arranged for slow and fast fading compensation, by programming the channel correction Pilot filter for slow fading, said channel correction Pilot filter first performing a coherent accumulation over a slot, and secondly performing a weighted average over previous-previous, previous, actual and next obtained slot values, yielding a channel estimation per slot, which is applied by said channel corrector;

and for fast fading, said channel correction Pilot filter first performing a coherent accumulation over a slot, and then deriving channel estimations through interpolating consecutive said coherent accumulations over a slot, yielding channel estimations with sub-symbol timing, which are applied by said channel corrector.

29. The communication device of the claim 1, wherein the reference demodulator comprises:

an accumulator of programmable length of the absolute values of samples at chip rate; and

a low pass filter operating on said accumulator output.

30. The communication device of claim 1, wherein the reference demodulator is arranged to operate in a runtime control loop by the processor.

31. The communication device of claim 1, wherein the demodulator is arranged to perform satellite diversity.

32. The communication device of claim 1, wherein the communication device is configured to perform accurate ranging measurements to geostationary satellites.

33. The communication device of claim 1, wherein the digital circuit performs arithmetic calculations to substantially remove the I, Q phase difference, the calculations comprising:

Iout+Iin+Qin*tan(B), and

Qout+Qin+Iin*tan(B),

where a compensation angle is 2B.

34. The communication device of claim 1, wherein the digital circuit uses a software configurable compensation angle.

35. The communication device of claim 1, wherein the digital circuit comprises:

an input register holding a compensation angle; and

a section adapted to perform arithmetic calculations to acquire a change of the I, Q angle by the compensation angle.

36. A communication device for W-CDMA signal transmission and reception, which is software configurable, comprising:

a W-CDMA transmitter comprising at least one of a RAM and registers;

a W-CDMA receiver comprising at least one of a RAM and registers;

a signal acquisition circuit;

a digital circuit for phase unbalance precompensation comprised in said W-CDMA transmitter, said digital circuit comprising;

an input register holding a compensation angle; and

a section adapted to perform arithmetic calculations to acquire a change of an I, Q angle by the compensation angle;

wherein the W-CDMA receiver comprises a level block control, the level block control comprising;

a programmable shifter to perform coarse grain dynamic control;

a programmable multiplier to perform fine grain dynamic control;

an overflow counter operating on a most significant bit and a second most significant bit; and

a saturation logic to clip a result from the multiplier.

37. A communication device for W-CDMA signal transmission and reception, which is software configurable, comprising:

a W-CDMA transmitter comprising at least one of a RAM and registers;

a W-CDMA receiver comprising at least one of a RAM and registers;

a signal acquisition circuit;

a digital circuit for phase unbalance precompensation comprised in said W-CDMA transmitter, said digital circuit comprising;

an input register holding a compensation angle; and

a section adapted to perform arithmetic calculations to acquire a change of an I, Q angle by the compensation angle;

wherein the W-CDMA receiver comprises a demodulator assigned to track multi-path components received from one base station, wherein the demodulator comprises;

a Rake filter producing a signal at a chip rate which is a coherent accumulation of channel corrected multipath components resulting from one base station;

a tracking unit using said signal at the chip rate for descrambling and despreading a plurality of waveform channels;

in which said Rake filter comprises;

a FIFO to buffer samples at chip rate coming from said level control block;

a delay line containing a plurality of registers, an input of the delay line being connected to an output of said FIFO;

a plurality of finger blocks, inputs of said finger blocks being connected to programmable tap positions on said delay line; and

a summator of complex outputs of said finger blocks at chip rate.

38. The communication device of claim 37, wherein the finger blocks are respectively grouped in a late multipath group and an early multipath group, the Rake filter being arranged to accumulate the energies of the outputs of said late multipath group and said early multipath group, and to use these accumulated values to feed the time error detector of the DLL for time tracking.

39. The communication device of claim 37, wherein the Rake filter comprises memories to hold at least one of a spreading code for a channel correction Pilot, a scrambling code for a channel correction Pilot, a channel correction Pilot symbol modulation, and a channel correction Pilot symbol activities.

40. The communication device of claim 39, wherein the memories are controlled by the processor.

41. The communication device of claim 39, wherein the finger block comprises:

a channel correction Pilot descrambler;

a channel correction Pilot despreader;

a channel correction Pilot filter, first performing a coherent channel correction Pilot symbol accumulation over a programmable number of steps, and secondly producing a weighted average on a programmable number of said coherent channel correction Pilot symbol accumulation over a programmable number of-steps;

a channel estimator generating a channel estimation at chip rate, using outputs of said Pilot filter;

a channel corrector performing a multiplication of an incoming chip stream with a complex conjugate of said channel estimation;

a calculation of a slot energy;

a comparison of the slot energy with a programmable threshold; and

a circuit to force said channel estimation to zero if said threshold is not exceeded.

42. The communication device of claim 41, wherein the finger is arranged for slow and fast fading compensation, by programming the channel correction Pilot filter for slow fading, said channel correction Pilot filter first performing a coherent accumulation over a slot, and secondly performing a weighted average over previous, previous, previous, actual and next obtained slot values, yielding a channel estimation per slot, which is applied by said channel corrector;

and for fast fading, said channel correction Pilot filter first performing a coherent accumulation over a slot, and then deriving channel estimations through interpolating consecutive said coherent accumulations over a slot, yielding channel estimations with sub-symbol timing, which are applied by said channel corrector.