Dynamic sectorization in a CDMA cellular system employing centralized base-station architecture

• US 6,353,600 B1
• Filed: 04/29/2000
• Issued: 03/05/2002
• Est. Priority Date: 04/29/2000
• Status: Expired due to Term

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: LGC Wireless Incorporated (TE Connectivity Limited)
• Inventors: Schwartz, Adam L., Lau, Kam-Yin
• Primary Examiner(s): Hsu, Alpus H.
• Assistant Examiner(s): Qureshi, Afsar M.
• Application Number:
  US09/562,598
• Time in Patent Office: 675 Days
• Field of Search: 370/203, 370/320, 370/328, 370/329, 370/335, 370/355, 370/535, 370/342, 370/441, 370/489, 359/115, 359/118, 359/124, 359/135, 359/136, 455/450, 455/452, 455/561, 455/562, 455/560, 455/442, 455/518, 455/519, 455/517, 455/509
• US Class Current: 370/328
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 24/00 Supervisory, monitoring or testing arrangements
• CPC Class Codes: H04W 28/24 Negotiating SLA [Service Level Agreement]; Negotiating QoS [Quality of Service]
• CPC Class Codes: H04W 28/26 Resource reservation
• CPC Class Codes: H04W 88/085 Access point devices with remote components

Abstract

This invention provides a cellular network architecture in which traffic channel resources are centralized and dynamically allocated to remote cells according to the demand. The present invention provides a method for maximizing capacity resources by dynamically sectorizing cells in a CDMA (Code Division Multiple Access) cellular network. The present invention further provides a CDMA cellular communications network in which centralized traffic channel resources are distributed to remote cells by use of WDM (Wavelength Division Multiplexing) on optical fibers and remote cells are dynamically sectorized according to the traffic demand and the grade-of-service requirement. The primary advantage of the present invention is that it enables a cellular network to dynamically manage and optimally utilize its capacity resources without having to change its hardware design, in contrast to the static and passive nature of the prior art cellular networks. The present invention provides a cost-effective build-out strategy for cellular network operators.

Claims

1. A cellular communications system comprising:

a) a base-station site containing one or more base-station units at a centralized location;

b) one or more remote cells;

c) a distribution means for transmitting traffic channel groups between said base-station site and said one or more remote cells; and

d) a management system in communication with said base-station site;

wherein said management system monitors offered traffic, a time-averaged number of simultaneous on-going calls, in each of said one or more remote cells, and dynamically determines an allocation of traffic channel groups to said one or more remote cells, wherein upon allocating a plurality of traffic channel groups to a particular remote cell by said base-station site, each of a number of antennae placed in said particular remote cell is assigned no more than one of said plurality of traffic channel groups, and wherein physical coverage areas provided by each and every of said number of antennae in said particular remote cell are mutually exclusive.

2. The cellular communications system of claim 1 wherein each of said plurality of traffic channel groups is a CDNA signal comprising one or more CDMA channels.

3. The cellular communications system of claim 2 wherein said CDMA signal is characterized by a PN code.

4. The cellular communications system of claim 1 wherein said distribution means comprises one or more optical fibers.

5. The cellular communications system of claim 4 further comprising:

a) a central unit that converts two or more downlink traffic channel groups transmitted from said base-station site to two or more downlink optical signals with downlink optical wavelengths such that said downlink traffic channel groups and said downlink optical wavelengths are in a one-to-one correspondence, and multiplexes said downlink optical signals onto said one or more optical fibers by use of wavelength division multiplexing (WDM); and

b) one or more remote units that de-multiplex said downlink optical signals with downlink optical wavelengths delivered by said one or more optical fibers and restore said two or more downlink traffic channel groups from said de-multiplexed downlink optical signals.

6. The cellular communications system of claim 5 wherein said one or more remote units convert uplink cellular signals transmitted from said one or more remote cells to one or more uplink optical signals with uplink optical wavelengths and multiplex said one or more uplink optical signals onto said one or more optical fibers by use of wavelength division multiplexing (WDM), and wherein said central unit de-multiplexes said one or more uplink optical signals from said one or more optical fibers and restores said uplink cellular signals from said de-multiplexed uplink optical signals.

7. The cellular communications system of claim 1 wherein said management system further comprises a monitoring means for measuring said offered traffic.

8. The cellular communications system of claim 7 wherein said traffic channel groups comprise CDMA channels, and wherein said monitoring means comprises a device capable of measuring a noise-level associated with said CDMA channels.

9. The cellular communications system of claim 7 wherein said management system employs an optimization algorithm, and wherein said optimization algorithm uses as input said offered traffic measured by said monitoring means and dynamically determines said allocation of said traffic channel groups to said one or more remote cells.

10. The cellular communications system of claim 9 wherein said traffic channel groups comprise CDMA signals, wherein said optimization algorithm assigns to said particular remote cell a fraction of a total number of CDMA signals available at said base-station site, wherein said fraction is approximately equal to a ratio of said offered traffic in said particular remote cell to a sum of said offered traffic in each and every of said one or more remote cells, subject to constraints that a number of CDMA signals assigned to said particular remote cell does not exceed said number of antennae placed in said particular remote cell, and said particular cell is assigned at least one CDMA signal.

11. The cellular communications system of claim 1 wherein said traffic channel groups are not orthogonal to each other.

12. A method of dynamically allocating traffic capacity in a cellular communications system comprising a centralized base-station site and one or more remote cells, comprising the steps of:

a) monitoring offered traffic in each of said one or more remote cells within said cellular communications system;

b) dynamically determining an allocation of traffic channel groups to said one or more remote cells;

c) transmitting one or more traffic channel groups from said base-station site to a particular remote cell, such that a plurality of traffic channel groups are assigned to said particular remote cell; and

d) dividing said particular remote cell into mutually exclusive physical sectors, such that each of said sectors is assigned one of said plurality of traffic channel groups.

13. The method of claim 12 wherein said step d) is accomplished by having said particular remote cell equipped with a plurality of directional antennae, wherein physical coverage areas provided by each and every of said plurality of directional antennae are mutually exclusive, and wherein each of said plurality of directional antennae is assigned no more than one of said plurality of traffic channel groups.

14. The method of claim 12 wherein said steps a) and b) are carried out by a management system in communication with said base-station site.

15. The method of claim 14 wherein said management system includes a monitoring means for measuring said offered traffic.

16. The method of claim 14 wherein said management system employs an optimization algorithm, and wherein said optimization algorithm determines said allocation of said traffic channel groups to said each of one or more remote cells.

17. The method of claim 16 wherein said traffic channel groups comprise CDMA signals and said particular remote cell is equipped with a number of antennae, wherein said optimization algorithm assigns to said particular remote cell a fraction of a total number of CDMA signals available at said base-station site, wherein said fraction is approximately equal to a ratio of said offered traffic in said particular remote cell to a sum of said offered traffic in each and every of said one or more remote cells, subject to constraints that a number of CDMA signals assigned to said particular remote cell does not exceed said number of antennae placed in said particular remote cell, and said particular remote cell is assigned at least one CDMA signal.

18. The method of claim 12 wherein said plurality of traffic channel groups are transmitted from said base-station site to said particular remote cell by one or more optical fibers.

19. The method of claim 18 further comprising:

a) converting two or more downlink traffic channel groups transmitted from said base-station site to two or more downlink optical signals with downlink optical wavelengths such that said downlink traffic channel groups and said downlink optical wavelengths are in a one-to-one correspondence and multiplexing said two or more downlink optical signals to said one or more optical fibers by use of wavelength division multiplexing; and

b) de-multiplexing said downlink optical signals delivered by said one or more optical fibers and restoring said two or more downlink traffic channel groups from said de-multiplexed downlink optical signals.

20. The method of claim 18 further comprising:

a) converting uplink cellular signals transmitted from said one or more remote cells to uplink optical signals with uplink optical wavelengths and multiplexing said uplink optical signals onto said one or more optical fibers by use of wavelength division multiplexing;

b) de-multiplexing said uplink optical signals from said one or more optical fibers and restoring said uplink cellular signals from said de-multiplexed uplink optical signals.

21. A cellular communications system comprising:

a) a centralized base-station site, containing one or more base-station units;

b) one or more optical fibers;

c) one or more remote cells, each equipped with a plurality of antennae;

d) a central unit connected to said one or more optical fibers, wherein said central unit is in communication with said base-station site;

e) one or more remote units connected to said one or more optical fibers, wherein said one or more remote units are in communication with said one or more remote cells; and

f) a management system in communication with said base-station site, wherein said management system supervises dynamic traffic capacity allocation to said one or more remote cells within said cellular communications system.

22. The cellular communications system of claim 21 wherein said management system monitors offered traffic a time-averaged number of simultaneous on-going calls) in each of said one or more remote cells, and determines an allocation of traffic channel groups to said one or more remote cells, wherein upon allocating a plurality of traffic channel groups to a particular remote cell by said base-station site, each of a number of antennae placed in said particular remote cell is assigned no more than one of said plurality of traffic channel groups, and wherein physical coverage areas provided by each and every of said number of antennae in said particular remote cell are mutually exclusive.

23. The cellular communications system of claim 22 wherein said management system further includes a monitoring means for measuring said offered traffic.

24. The cellular communications system of claim 22 wherein said management system employs an optimization algorithm, and wherein said optimization algorithm determines said allocation of said traffic channel groups to said one or more remote cells.

25. The cellular communications system of claim 24 wherein said traffic channel groups comprise CDNA signals, wherein said optimization algorithm assigns to said particular remote cell a fraction of a total number of CDMA signals available at said base-station site, wherein said fraction is approximately equal to a ratio of said offered traffic in said particular remote cell to a sum of said offered traffic in each and every of said one or more remote cells, subject to constraints that a number of CDMA signals assigned to said particular remote cell does not exceed said number of antennae placed in said particular remote cell, and said particular remote cell is assigned at least one of said CDMA signals.

26. The cellular communications system of claim 21 wherein said central unit converts two or more downlink traffic channel groups transmitted from said base-station site to downlink optical signals with downlink optical wavelengths such that said downlink traffic channel groups and said downlink optical wavelengths are in a one-to-one correspondence and multiplexes said downlink optical signals to said one or more optical fibers by use of wavelength division multiplexing, and wherein said one or more remote units de-multiplex said downlink optical signals with downlink optical wavelengths delivered by said one or more optical fibers and restore said two or more downlink traffic channel groups from said demultiplexed downlink optical signals.

27. The cellular communications system of claim 21 wherein one or more remote units convert uplink CDMA signals transmitted from said one or more remote cells to uplink optical signals with uplink optical wavelengths and multiplex said uplink optical signals onto said one or more optical fibers by use of WDM, and wherein said central unit de-multiplexes said uplink optical signals from said one or more optical fibers and restores said uplink CDMA signals from said de-multiplexed uplink optical signals.