Linear coverage area antenna system for a CDMA communication system

• US 5,602,834 A
• Filed: 06/07/1995
• Issued: 02/11/1997
• Est. Priority Date: 12/07/1990
• Status: Expired due to Term

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Dean, Richard F., Antonio, Franklin P.
• Primary Examiner(s): MARCELO, MELVIN C
• Application Number:
  US08/483,111
• Time in Patent Office: 615 Days
• Field of Search: 370/18, 375/200, 375/205, 375/347, 455/276.1, 455/277.2, 455/278.1, 455/279.1, 455/283, 342/375, 342/433, 342/434, 343/844, 343/853
• US Class Current: 370/335
• CPC Class Codes: H01Q 21/29 Combinations of different interacting antenna units for giving a desired directional characteristic H01Q25/00 takes precedence
• CPC Class Codes: H04B 7/022 Site diversity; Macro-diversity using two or more spaced independent antennas H04B7/04
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04B 7/0671 using different delays between antennas
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04B 7/0894 using different delays between antennas
• CPC Class Codes: H04B 7/2628 using code-division multiple access [CDMA] or spread spectrum multiple access [SSMA] H04B7/2618 takes precedence
• CPC Class Codes: H04B 7/2643 using time-division multiple access [TDMA] H04B7/2615, H04B7/2618 take precedence
• CPC Class Codes: H04W 36/18 for allowing seamless reselection, e.g. soft reselection
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

A linear coverage area antenna system for use within a CDMA communication system is described. In a preferred implementation, two linear coverage area antenna structures are positioned in parallel and coupled to a base station. Within the base station, a transmitter generates remote user directed spread spectrum signals, these signals being provided to the first and second linear coverage area antenna structures through an antenna interface. The antenna interface includes a time delay element for introducing a predetermined time delay between components of the remote user directed spread spectrum signals transmitted by the first and second linear coverage area antenna structures, respectively. The base station also further includes at least a first demodulation element for demodulating an aggregate spread spectrum signal comprised of a plurality of system user directed spread spectrum signals received by the first linear coverage area antenna structure and a second demodulation element for demodulating a second aggregate spread spectrum signal comprised of a plurality of system user directed spread spectrum signals received by the second linear coverage area antenna structure.

Claims

1. In a digital communication system in which at least one remote terminal is in communication with a base station using digitally modulated communication signals, said base station having an antenna system comprising:

a first linear coverage area antenna structure;

a second linear coverage area antenna structure; and

antenna interface means for coupling said communication signals between said base station and said first and second linear coverage area antenna structures, said antenna interface means including means for splitting ones of said communication signals into first and second time-offset signal components for transmission by said first and second linear coverage area antenna structures, respectively.

2. The antenna system of claim 1 wherein said antenna interface means includes first and second duplexers, said first and second duplexers being interposed between an analog transmitter within said base station and said first and second linear coverage area antenna structures, respectively.

3. The antenna system of claim 2 wherein said antenna interface means includes a splitter and delay network and wherein said communication signals are generated by spread spectrum modulating information signals according to predetermined pseudorandom noise (PN) spreading codes each comprised of a predetermined sequence of binary chips each of a predetermined chip duration, said splitter and delay network providing a delay between said first and second time-offset signal components on an order of at least one chip duration.

4. The system of claim 1 wherein said first and second linear coverage area antenna structures respectively comprise first and second leaky coaxial antennas.

5. In a digital communication system in which system users communicate through a base station with remote system users, said remote system users communicating through said base station via a radio link therewith, said base station comprising:

a first linear coverage area antenna structure;

a second linear coverage area antenna structure;

transmitter means for generating remote user directed spread spectrum signals by spread spectrum modulating system user information signals; and

antenna interface means for providing said remote user directed spread spectrum signals to said first and second linear coverage area antenna structures, said antenna interface means including means for introducing a predetermined time delay between components of said remote user directed spread spectrum signals transmitted by said first and second linear coverage area antenna structures, respectively.

6. The base station of claim 5 further comprising first means for demodulating a first aggregate spread spectrum signal coupled from said first antenna structure, said first aggregate spread spectrum signal being comprised of a plurality of system user directed spread spectrum signals received by said first linear coverage area antenna structure.

7. The base station of claim 6 further comprising second means for demodulating a second aggregate spread spectrum signal coupled from said second antenna structure, said second aggregate spread spectrum signal being comprised of a plurality of system user directed spread spectrum signals received by said second linear coverage area antenna structure.

8. The base station of claim 5 wherein said system user information signals are spread spectrum modulated according to predetermined pseudorandom noise (PN) spreading codes each comprised of a predetermined sequence of binary chips each of a predetermined chip duration, said predetermined time delay being on an order of at least one chip duration.

9. The base station of claim 5 wherein said first and second linear coverage area antenna structures respectively comprise first and second leaky coaxial antennas.

10. The base station of claim 5 wherein said first and second linear coverage area antenna structures are disposed to radiate electromagnetic energy substantially continuously along a longitudinal dimension thereof.

11. A system for transmitting a forward link spread spectrum modulated information signal and receiving a reverse link spread spectrum modulated information signal wherein said forward and reverse spread spectrum modulated information signals are generated by spread spectrum modulating information signals with pseudorandom noise codes each predetermined pseudorandom noise code comprised of a predetermined sequence of code chips each of a predetermined chip duration, said system comprising:

a first antenna structure having a linear coverage area;

a second antenna structure having a linear coverage area; and

antenna interface means for providing said forward link spread spectrum modulated information signal to said first and second linear coverage area antenna structures, said antenna interface means including means for introducing a delay equivalent to at least one of said predetermined chip durations between components of said forward link spread spectrum modulated information signal transmitted by said first and second antenna structures, respectively;

wherein said linear coverage area of said first antenna structure and said linear coverage area of said second antenna structure substantially overlap.

12. The system of claim 11 further comprising a plurality of demodulation elements wherein a first one of said plurality of demodulation elements receives a first component of said reverse link spread spectrum signal from said first antenna structure and a second one of said plurality of demodulation elements receives a component of said reverse link spread spectrum signal from said second antenna structure.

13. The system of claim 12 wherein said first and second ones of said demodulation elements each demodulate a signal from a common remote user further comprising a diversity combiner for combining an output of said first one of said demodulation elements and an output of said second one of said demodulation elements.

14. The system of claim 13 further comprising a searcher engine for identifying multiple receptions of said signal from said common remote unit.

15. The system of claim 12 further comprising an interface switch for coupling a third one of said plurality of demodulation elements either to said component of said reverse link spread spectrum signal from said first antenna structure or to said component of said reverse link spread spectrums signal from said second antenna structure.

16. The system of claim 11 wherein said first antenna structure is a leaky coaxial cable.

17. The system of claim 11 wherein said first antenna structure is triaxial coax cable.

18. The system of claim 11 further comprising a remote unit located within said substantial overlap wherein said remote unit comprises a plurality of demodulation elements for demodulating a chosen forward link signal within said component of said forward link spread spectrum modulated information signal transmitted by said first antenna structure and for demodulating said chosen forward link signal within said component of said forward link spread spectrum modulated information signal transmitted by said second antenna structure, respectively.

19. In a digital communication system in which at least one remote terminal is in communication with a base station using digitally modulated communication signals, a method for effecting distributed transmission of said digitally modulated communication signals comprising the steps of:

providing a first linear coverage area antenna structure;

providing a second linear coverage area antenna structure; and

splitting ones of said digitally modulated communication signals from said base station into first and second signal components of different time delay, and coupling said first and second signal components of said digitally modulated communication signals to said first and second linear coverage area antenna structures.

20. The method of claim 19 wherein said communication signals are generated by spread spectrum modulating information signals according to predetermined pseudorandom noise (PN) spreading codes each comprised of a predetermined sequence of binary chips each of a predetermined chip duration, further including the step of providing a delay between said first and second signal components of different time delay on an order of at least one chip duration.

21. In a digital communication system in which system users communicate through a base station with remote system users, said remote system users communicating through said base station via a radio link therewith, a method for effecting distributed transmission and reception of spread spectrum communication signals at said base station comprising the steps of:

providing a first linear coverage area antenna structure;

providing a second linear coverage area antenna structure;

generating remote user directed ones of said spread spectrum signals by spread spectrum modulating user information signals; and

providing said remote user directed ones of said spread spectrum signals to said first and second linear coverage area antenna structures, and introducing a predetermined time delay between components of said remote user directed ones of said spread spectrum signals transmitted by said first and second linear coverage area antenna structures, respectively.

22. The method of claim 21 further including the step of demodulating a first aggregate spread spectrum signal coupled from said first antenna structure, said first aggregate spread spectrum signal being comprised of a plurality of system user directed ones of said spread spectrum signals received by said first linear coverage area antenna structure.

23. The method of claim 22 further including the step of demodulating a second aggregate spread spectrum signal coupled from said second antenna structure, said second aggregate spread spectrum signal being comprised of a plurality of system user directed ones of said spread spectrum signals received by said second linear coverage area antenna structure.

24. The antenna system of claim 21 wherein said first and second linear coverage area antenna structures are separated by greater than a wavelength of said spread spectrum communication signals while maintain substantially overlapping coverage areas.

25. In a digital communication system in which at least one remote terminal is in communication with a base station using digitally modulated communication signals, said base station having an antenna system comprising:

a first linear coverage area antenna structure conveying a digitally modulated communication signal and comprised of a first segment having a first segment coverage area and a second segment having a second segment coverage area; and

a series element disposed between said first segment and said second segment and providing delay between said digitally modulated communication signal conveyed by said first segment and said digitally modulated communication signal conveyed by said second segment.

26. The antenna system of claim 25 wherein said series element provides amplification of said digitally modulated communication signal.

27. The antenna system of claim 25 wherein said first segment coverage area and said second segment coverage area overlap.

28. The system of claim 27 further comprising a remote unit located within said overlap of said first and second coverage areas wherein said remote unit comprises a plurality of demodulation elements for demodulating a chosen forward link signal within said digitally modulated communication signal conveyed by said first segment and for demodulating said chosen forward link signal within said digitally modulated communication signal conveyed by said second segment.