Adaptive-Dynamic channel assignment organization system and method

• US 5,809,423 A
• Filed: 04/18/1996
• Issued: 09/15/1998
• Est. Priority Date: 03/09/1995
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Benveniste, Mathilde
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Armstrong, Darnell R.
• Application Number:
  US08/634,320
• Time in Patent Office: 880 Days
• Field of Search: 455/33.1, 455/33.2, 455/33.4, 455/34.1, 455/53.1, 455/54.1, 455/62, 455/63, 455/67.1, 455/67.2, 455/450, 455/451, 455/452, 455/453, 455/464, 455/561, 379/59, 379/60
• US Class Current: 455/452.2
• CPC Class Codes: H04W 16/04 Traffic adaptive resource partitioning
• CPC Class Codes: H04W 16/06 Hybrid resource partitioning, e.g. channel borrowing
• CPC Class Codes: H04W 16/18 Network planning tools
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 28/26 Resource reservation

Abstract

A channel assignment system allocates channels to various cells by the optimal partitioning of the available radio frequencies into non-overlapping sets, the optimal grouping of co-user cells, and the best allocation of the former to the latter. Maximization of traffic handling capacity is, for one embodiment, expressed as the maximization of a bottleneck capacity ratio, known as the capacity factor. The capacity ratio for a cell is defined as the ratio of the number of radio frequencies allocated to the cell over the number of radio frequencies needed to meet blocking probability requirements. Given a channel allocation, the latter is fixed once the traffic loads and desired blocking are specified. The solution to attain an optimal non-regular channel assignment is decomposed into two mathematical programs designated a Master Program and a Subprogram. These are solved iteratively with assistance from a channel set augmentation technique implemented between solutions of the Master and Subprogram. A method is also provided for periodic reallocation of channels to cells to address changing capacity requirements in individual cells. A further methodology is provided where a cell, having exhausted its available allocated channels, may "borrow" channels, i.e., it may use channels that are not allocated to the cell.

Claims

1. In a wireless communications system having service areas partitioned into a plurality of substantially contiguous cells, a method of assigning radio channels to said cells comprising the steps of:

determining an initial allotment of an available channel set among said plurality of cells based on an established set of traffic and interference data;

measuring traffic and interference data for said cells on a substantially real-time basis, said measure traffic data including at least blocking and signal-to-interference (S/I) data for a given channel;

periodically reallocating channels among said plurality of cells based on said measured traffic and interference data; and

dynamically adjusting said channel allotment during intervals between said periodic reallocation of channels based on contemporaneously measured traffic and interference data.

2. In a wireless communications system having service areas partitioned into a plurality of substantially contiguous cells, the method of assigning radio channels to said cells of claim 1 wherein said step of dynamically adjusting said channel allotment includes the further steps of:

determining if, upon arrival of a new channel request, a cell has exhausted an assigned allocation of channels;

determining if a free channel exists, among channels allocated to said cell, that would meet interference and system constraints if assigned to said new channel request, given current use of said channel;

determining if a free channel exists, among channels not allocated to said cell, that would meet interference and system constraints if assigned to said new channel request, given current use of said channel;

assigning said request to said free channel meeting interference and system constraints.

3. In a wireless communications system having service areas partitioned into a plurality of substantially contiguous cells, the method of assigning radio channels to said cells as claimed in claim 2, including the further steps of:

determining, for a cell potentially able to provide one or more channels from its channel allocation (hereafter "donor cell") to another cell requesting a non-allocated channel (hereafter "requestor cell"), a portion of said donor cell'"'"'s allocated channels to be reserved for said donor cell'"'"'s own use;

determining, at said arrival of said new channel request, whether said donor cell has available said reserved portion before allowing said free channel to be borrowed by said requester cell.

4. In a wireless communications system having service areas partitioned into a plurality of substantially contiguous cells, the method of assigning radio channels to said cells as claimed in claim 3, wherein said step of determining a portion of said donor cell'"'"'s allocated channels to be reserved for said donor cell'"'"'s own use is carried out in real time as a function of system performance.

5. In a wireless communications system having service areas partitioned into a plurality of substantially contiguous cells, the method of assigning radio channels to said cells as claimed in claim 2, comprising the further steps of:

determining if a channel released at a call termination is other than a borrowed channel; and

transferring an existing call on a borrowed channel to a non-borrowed released channel.

6. In a wireless communications system having service areas partitioned into a plurality of substantially contiguous cells, the method of assigning radio channels to said cells as claimed in claim 2, wherein, upon an allocated channel becoming available in a cell, a channel assignment for a non-allocated channel in said cell is released and a call using said channel assignment transferred to said available allocated channel (hereafter "channel rearrangement"), and comprising the further step of:

prohibiting said channel rearrangements in excess of a pre-determined number per call.

7. In a wireless communications system having service areas partitioned into a plurality of substantially contiguous cells, the method of assigning radio channels to said cells as claimed in claim 2, wherein, upon an allocated channel becoming available in a cell, a channel assignment for a non-allocated channel in said cell is released and a call using said channel assignment transferred to said available allocated channel (hereafter "channel rearrangement"), and comprising the further step of:

establishing a minimum time interval between consecutive occurrences of said channel rearrangements for a given call.