Method and apparatus of assigning and sharing channels in a cellular communication system

• US 5,722,043 A
• Filed: 07/25/1995
• Issued: 02/24/1998
• Est. Priority Date: 02/05/1993
• Status: Expired due to Fees

• Current Assignee: The Research Foundation for The State University of New York (State University of New York)
• Original Assignee: The Research Foundation for The State University of New York (State University of New York)
• Inventors: Jiang, Hua, Rappaport, Stephen S.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Armstrong, Darnell R.
• Application Number:
  US08/506,506
• Time in Patent Office: 945 Days
• Field of Search: 455/33.1, 455/33.4, 455/34.1, 455/54.1, 455/56.1, 455/67.1, 379/59
• US Class Current: 455/452.1
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 16/12 Fixed resource partitioning
• CPC Class Codes: H04W 16/24 Cell structures
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]

Abstract

A method of assigning and sharing carriers in a cellular communications system having a plurality of cells forming a plurality of cell clusters of size N. Each cell has at least one base station capable of sending and receiving signals and each cell has a plurality of adjacent cells. A plurality of distinct carriers are allotted for use by the system and divided into N groups which are assigned among the N cells of each cell cluster so that each cell cluster has a substantially similar assignment of distinct carrier groups. Each group of distinct carriers is divided into a plurality of carrier subgroups wherein each subgroup of carriers of a cell substantially corresponds to an adjacent cell. The subgroups of carriers are respectively designated for borrowing by cells adjacent to a corresponding cell. When all of the carriers assigned to a cell are utilized, a carrier can be borrowed at limited transmitted power, from a corresponding subgroup of carriers of an adjacent cellular gateway. The borrowed carrier is used with limited transmitted power so that co-channel interference caused by the carrier borrowing is essentially the same as that without carrier borrowing. A method is also provided for assigning and sharing carriers and prioritizing the order of return of the carriers from a borrowing cell to a lending cell.

Claims

1. A method of permitting real-time borrowing of carriers in a cellular communication system having a plurality of distinct carriers, the cellular communication system having a plurality of substantially similar cell clusters, each cell cluster having a plurality of cells wherein each cell has at least one base station capable of sending and receiving transmissions, each cell having a plurality of adjacent cells, the method comprising the steps of:

determining a total number of distinct carriers (CT) available for use by the cellular communication system, the total number of distinct carriers being at most equal to the plurality of distinct carriers;

specifying a cell cluster size (N) for the cellular communication system where N=the number of cells in a cell cluster;

selecting N disparate groups of carriers from the total number of distinct carriers, each carrier within the N disparate groups of carriers being substantially distinct from any other carrier within the N disparate groups of carriers;

respectively assigning the N disparate groups of carriers to the N cells of each cell cluster wherein one carrier group is assigned to each cell; and

segmenting the group of carriers assigned to each respective cell into a plurality of carrier subgroups assigned for lending to a predetermined adjacent cell, the number of carrier subgroups respectively corresponding to at least the plurality of adjacent cells, the carriers of each of the carrier subgroups being respectively designated for lending from the respective cell to said predetermined adjacent cell.

2. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 1, the cellular communication system including a first cell within a first cell cluster, the first cell being assigned a first group of the N groups of carriers assigned to the first cell cluster, the first cell having a plurality of adjacent cells, the method further comprising the steps of:

receiving a request at a first cell base station for use of a carrier by the first cell base station, the request for use corresponding to a new call within the first cell;

determining whether each carrier of the first group of carriers assigned to the first cell is in use;

wherein if each carrier of the first group of carriers assigned to the first cell is in use, determining whether a carrier of the carrier subgroups assigned to the plurality of cells adjacent to the first cell and designated for lending to the first cell, is available for use by the first cell base station; and

transferring the available carrier from a respective adjacent cell to the first cell base station to service the new call, where upon transfer, the available carrier constitutes a borrowed carrier.

3. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 2, which includes the further step of temporarily transferring the borrowed carrier from the respective adjacent cell to the first cell, wherein the borrowed carrier being returned to the respective adjacent cell after the new call on the borrowed carrier is complete.

4. A method of permitting real-time borrowing of carriers, in a cellular communication system as defined by claim 2, which includes the further step of making the borrowed carrier unavailable for use in the respective adjacent cell while the borrowed carrier is being utilized in the first cell.

5. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 2, which further includes the step of simultaneously utilizing the borrowed carrier for transmission in any of the plurality of cell clusters while the borrowed carrier is used by the first cell.

6. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 2 , which includes the further step of utilizing the borrowed carrier with reduced power, the borrowed carrier being capable of being utilized in a region proximate to the first cell base station.

7. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 2, the method further comprising the steps of:

generating a borrowed carrier sensing signal within each cell of the plurality of cell clusters, the borrowed carrier sensing signal emanating from a point proximate to the base station of a corresponding cell, the borrowed carrier sensing signal providing an indication as to whether a first user, located within the first cell is in a region of the first cell proximate to the base station so as to utilize a carrier of a subgroup of carriers assigned to cells adjacent to the first cell and designated for lending to the first cell.

8. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 2, the method further comprising the steps of:

generating a borrowed carrier sensing signal within each cell of the plurality of cell clusters, the borrowed carrier sensing signal emanating from user mobile stations located within each cell, the borrowed carrier sensing signal providing an indication as to whether a first user, located within the first cell is in a region of the first cell proximate to the base station so as to utilize a carrier of a subgroup of carriers assigned to cells adjacent to the first cell and designated for lending to the first cell.

9. A method of permitting real-time borrowing of carriers in the cellular communication system as defined by claim 8, the method further comprising the steps of:

monitoring the borrowed carrier sensing signal to determine whether a new user, located in the first cell and utilizing a first carrier assigned to the first cell, is distally located from the base station of the first cell and incapable of utilizing a carrier of the subgroup of carriers assigned to cells adjacent to the first cell and designated for lending to the first cell;

monitoring the borrowed carrier sensing signal to determine whether the first user, is proximate to the base station of the first cell; and

wherein if the first user is proximate to the base station of the first cell and if the new user is distally located from the base station of the first cell, rearranging the carriers within the first cell, by providing the first user with a carrier from one of the sub-groups of carriers assigned to cells adjacent to the first cell and designated for lending to the first cell, and providing the new user with the first carrier which was previously utilized by the first user.

10. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 2, the method further comprising the steps of:

setting a threshold number (T) of carriers for simultaneous use within a respective adjacent cell where T=the maximum number of carriers of the disparate group of carriers assigned to the respective adjacent cell which can be simultaneously used in the respective adjacent cell;

monitoring carrier usage within the respective adjacent cell to determine whether the number of carriers being used in the respective adjacent cell is at least equal to the threshold number of carriers;

wherein if at least the threshold number of carriers are in use in the respective adjacent cell, preventing a transfer by the respective adjacent cell of one of the carriers of the subgroup of carriers respectively designated for lending from the respective adjacent cell to the first cell.

11. A method of permitting real-time borrowing of carriers without locking in a cellular communication system as defined by claim 2 wherein if a second carrier of the disparate group of carriers assigned to the first cell becomes available for use after the borrowed carrier is transferred to the first cell from one of the plurality of adjacent cells, the method further comprising the steps of:

transferring the transmission of the current signal from the borrowed carrier to the second carrier of the disparate group of carriers assigned to the first cell; and

returning the borrowed carrier to the respective adjacent cell from which it was borrowed.

12. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 2 wherein if the first cell receives a channel borrowing request for use of a carrier and each carrier of the first group of carriers are occupied so that the first cell requests to borrow a carrier from one of the carrier subgroups designated for lending to the first cell from a respective adjacent cell, and if the carrier subgroups of adjacent cells designated for lending to the first cell are in use including a third carrier in a first adjacent cell which is transmitting a third signal, and if a fourth carrier which belongs to a carrier subgroup of the first adjacent cell that is not designated for lending to the first cell is available for use within the first adjacent cell, the method further comprising the steps of:

transferring the third signal from the third carrier to the fourth carrier of the first adjacent cell, the fourth carrier being used for transmission of the third signal; and

transferring the third carrier from the first adjacent cell to the first cell for use by the first cell in order to accommodate the carrier borrowing request.

13. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 1, the method further comprising the steps of:

orienting the cells which have common distinct carrier assignments in the plurality of cell clusters so that cells having substantially the same group of distinct carriers are equidistant from one another.

14. A method of permitting real-time borrowing of carriers in a cellular communication system having a plurality of distinct carriers, the cellular communication system having a plurality of substantially similar cell clusters, each cell cluster having a plurality of sectorized cells wherein each sectorized cell has a plurality of sector areas, each sectorized cell having a plurality of sectorized base stations capable of sending and receiving transmissions in a corresponding sectorized area of the cell, each sector area having a plurality of adjacent sectorized cells, the method comprising the steps of:

determining a total number of distinct channels (C_T) available for use by the cellular communication system, the total number of distinct carriers being at most equal to the plurality of distinct carriers;

specifying a cell cluster size (N) for the cellular communication system where N=the number of sectorized cells in a cell cluster;

selecting N disparate groups of carriers from the total number of distinct carriers, each carrier within the N disparate groups of carriers being substantially distinct from any other carrier within the N disparate groups of carriers;

respectively assigning the N disparate groups of carriers to the N sectorized cells of each cell cluster wherein one carrier group is assigned to each sectorized cell;

respectively dividing the group of carriers assigned to each respective sectorized cell into a plurality of sectorized carrier groups corresponding to the number of sectorized base stations within each sectorized cell; and

segmenting each sectorized carrier group into a plurality of sectorized carrier subgroups assigned for lending to a predetermined adjacent cell, the number of sectorized carrier subgroups respectively corresponding to at least the plurality of adjacent sectorized cells, the channels of each of the sectorized carrier subgroups being respectively designated for lending from the respective sector area to one said predetermined adjacent sectorized cell.

15. A method of permitting real-time borrowing of carriers in a cellular communication system as defined by claim 14, the cellular communication system including a first sector area within a first sectorized cell within a first cell cluster, the first sectorized cell being assigned a first group of the N groups of carriers assigned to the first cell cluster, the first sectorized cell having a plurality of sector areas and corresponding sectorized base stations with respective sectorized carrier subgroups assigned thereto, the first sector area having a plurality of adjacent sectorized cells, the method further comprising the steps of:

receiving a request, at a first sectorized base station, for use of a carrier by the first sector area, the request for use corresponding to a new call within the first sector area;

determining whether each carrier of a first group of sectorized carrier subgroups assigned to the first sectorized base station of the first sector area is in use;

wherein if each carrier of the first group of sectorized carrier subgroups assigned to the first sectorized base station is in use, determining whether a carrier of the sectorized carrier subgroups assigned to the plurality of sector areas adjacent to the first cell and designated for lending to the first cell, is available for use by the first sectorized base station; and

transferring the available carrier from a respective sector area in an adjacent sectorized cell to the first sectorized base station to service the new call, where upon transfer, the available carrier constitutes a borrowed carrier.

16. A cellular communication system permitting real-time borrowing of carriers, the cellular communication system comprising:

a plurality of carriers; and

a plurality of cell clusters, each of the plurality of cell clusters having a plurality of cells, each of the plurality of cells having a plurality of adjacent cells and at least one transmitter, the plurality of carriers being divided into a first plurality of carrier groups corresponding to the plurality of cells utilized for each cell cluster, each carrier group of the first plurality of carrier groups being respectively assigned to one of the plurality of cells of each cell cluster for lending to a predetermined adjacent cell, each carrier group of the first plurality of carrier groups being further divided into a plurality of carrier sub-groups, the plurality of carrier sub-groups being at least equal to the number of adjacent cells, the carriers of each carrier sub-groups respectively being designated for lending to the transmitter of said predetermined adjacent cell.

17. A cellular communication system permitting real-time borrowing of carriers as defined by claim 16, wherein each cell cluster is adjacent to at least one other cell cluster.

18. A cellular communication system permitting real-time borrowing of carriers as defined by claim 16, wherein each of the plurality of cell clusters has substantially the same orientation of cells and wherein each of the plurality of cell clusters has substantially the same plurality of carrier groups and substantially the same plurality of carrier sub-groups assigned to corresponding cells.

19. A cellular communication system permitting real-time borrowing of carriers as defined by claim 16, wherein each cell includes a plurality of sectorized base stations, each sectorized base station providing transmission and reception in a respective direction, the plurality of unidirectional base stations providing omnidirectional coverage for the corresponding cell.

20. A method of returning a borrowed carrier signal from a borrowing cell to a lending cell in a cellular communication system, the carrier signal corresponding to a plurality of channels, the cellular communication system having a plurality cell clusters, each cell cluster having a plurality of cells wherein each cell has at least one base station capable of at least one of sending and receiving transmissions on the plurality of channels of the plurality of carrier signals, each cell having a plurality of adjacent cells, the borrowing cell borrowing at least a first and second carrier signal from at least one of the plurality of adjacent cells, the at least one of the plurality of adjacent cells corresponding to a lending cell, the at least a first and second carrier signal corresponding to a borrowed carrier for signal transmission of a call from the borrowing cell, the method comprising:

determining from which of the plurality of adjacent cells the borrowing cell received at least first and second carrier signals; and

for each of the plurality of adjacent cells that provide at least first and second carrier signals to the borrowing cell, selecting one of the first and second carrier signals as a primary borrowed carrier and one of the first and second carrier signals as a nonprimary borrowed carrier, the primary borrowed carrier being given priority for return to the corresponding lending cell over the non-primary borrowed carrier.

21. A method of returning a borrowed carrier signal from a borrowing cell to a lending cell in a cellular communication system as defined by claim 20, the borrowing cell having a plurality of borrowing cell carriers and corresponding borrowing cell channels, the method further comprising the steps of:

determining whether at least one of the plurality of borrowing cell channels is available for signal transmission of a call;

selecting one of the plurality of adjacent cells from which the borrowing cell received at least first and second carrier signals as a transfer cell; and

transferring a call from the primary borrowed carrier of the transfer cell to the available channel of the borrowing cell.

22. A method of returning a borrowed carrier signal from a borrowing cell to a lending cell in a cellular communication as defined by claim 20, the method further comprising the steps of:

determining whether a channel of the non-primary borrowed carrier is available for signal transmission of a call; and

transferring a call from one of the channels of the primary borrowed carrier to the available channel of the non-primary borrowed carrier.

23. A method of permitting real time borrowing of carrier signals in a cellular communication system, each carrier signal corresponding to a plurality of channels, the cellular communication-system having a plurality of cell clusters, each cell cluster having a plurality of cells including at least first and second cells, wherein each of the plurality of cells utilizes at least one base station capable of at least one of sending and receiving signal transmissions corresponding to calls on a plurality of carrier signals, each cell having a plurality of carrier signals and a plurality of adjacent cells, the method comprising the steps of:

a. receiving a request to transmit or receive a new call within the first cell, the request being the result of the new call within the first cell;

b. determining whether each of the plurality of carriers of the first cell are unavailable to transmit or receive the new call;

c. transmitting a carrier borrowing request from the first cell to at least one of the plurality of adjacent cells;

d. determining whether the at least the plurality of adjacent cells should one of grant or deny the carrier borrowing request transmitted by the first cell, where the at least one of the plurality of adjacent cells corresponds to a prospective lending cell.

24. A method of permitting real time borrowing of carrier signals in a cellular communication as defined by claim 23, wherein step (d) further comprises:

determining whether the number of carrier signals provided from the prospective lending cell to the first cell is substantially equal to a predetermined value A, wherein if the number of carrier signals provided from prospective lending cell to the first cell is less than A, the prospective lending cell will provide a carrier signal to the first cell to accommodate the new call, and wherein if the number of carrier signals provided from the prospective lending cell to the first cell is at least equal to A, the prospective lending cell will deny the request to provide a carrier signal to the first cell to accommodate the new call.

25. A method of permitting real time borrowing of carrier signals in a cellular communication as defined by claim 23, wherein step (d) of the method further comprises:

determining whether the number of carrier signals provided from the prospective lending cell to each of the plurality of adjacent cells is substantially equal to a predetermined value B, wherein if the number of carrier signals provided by the prospective lending cell to each of a plurality of calls adjacent to the prospective lending cell is less than B, the lending cell will provide a carrier signal to the first cell to accommodate the new call, and wherein if the number of carrier signals provided by the prospective lending cell to each of the plurality of cells adjacent to the prospective lending cell is at least equal to B, the prospective lending cell will deny the request to provide a carrier to the first cell to accommodate the new call.

26. A method of permitting real-time borrowing of carrier signals in a cellular communication as defined by claim 23, the prospective lending cell having a first carrier including a plurality of channels, wherein step (d) of the method further comprises:

determining whether each of the plurality of channels of the first carrier of the prospective lending cell are available for transmission, wherein if each of the plurality of channels of the first carrier of the prospective lending cell are available for transmission, providing the first carrier to the first cell to accommodate the new call, and wherein if at least one of the plurality of channels of each of the plurality of carrier signals of the prospective lending cell are unavailable, the prospective lending cell will deny the request to provide a carrier signal to the first cell to accommodate the new call.