Method and apparatus for dynamic channel allocation

• US 5,280,630 A
• Filed: 01/21/1992
• Issued: 01/18/1994
• Est. Priority Date: 01/21/1992
• Status: Expired due to Fees

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Wang, Zhonghe
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): FAILE, ANDREW I
• Application Number:
  US07/823,531
• Time in Patent Office: 728 Days
• Field of Search: 455/33.1, 455/34.1, 455/34.2, 455/62, 455/63, 455/67.3, 379/58-59, 379/61-63
• US Class Current: 455/452.2
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 36/08 Reselecting an access point
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/20 Control channels or signalling for resource management
• CPC Class Codes: H04W 72/542 using measured or perceived quality
• CPC Class Codes: H04W 88/02 Terminal devices
• CPC Class Codes: Y02D 30/70 in wireless communication networks

Abstract

A base station (21, 22, 23) in a radio communication system (20) comprises a channel allocator (62) for allocating communication channels in accordance with a fully distributed dynamic channel allocation method. The channel allocator accesses a Preferred Channel List (PCL) (64) to allocate the communication channels. The PCL ranks channels (116) in accordance with the occurrence of prior events on the channels (112), such as interrupted calls (122), blocked call setup requests (118), and calls successfully completed (106) and in regards to the mean quality margin (110) and the current channel quality (114). The channel allocator (62) allocates (140) the first available channel (128) in the PCL having a free timeslot (132) and with good current channel quality (136). Alternatively, the channel allocator (62) allocates communication channels in accordance with an optimal dynamic channel allocation method. A list of channels assigned to the base station is updated by removing channels (372) that are locally heavy loaded (366) and in poor quality (370) and by adding channels (390) if the channels are locally heavy loaded (384), and in good quality (394) for a period of time (392). Unassigned channels may be borrowed (388) if they are in good quality (382), are in a locally lightly loaded period (384), and have been idle for a predetermined period of time (386). The assigned channels of the base station (340) are allocated first (356, 360), with the borrowed channels being allocated (350) when no assigned channels are available (340).

Claims

1. In a radio communication system comprising a plurality of base stations and at least one handset for communicating on a plurality of channels, a method for channel allocation comprising the steps of:

(a) receiving a request for channel allocation at one of the plurality of base stations from one of the at least one handset;

(b) allocating one of the plurality of channels for the one of the at least one handset to communicate, the one of the plurality of channels allocated in accordance with a mean margin value of a plurality of measured margins of channel quality of the one of the plurality of channels in relationship to a predetermined threshold channel quality; and

(c) recalculating the mean margin value of each of the plurality of channels upon each occurrence of a successfully completed call thereon.

2. In a radio communication system comprising a plurality of base stations and at least one handset for communicating on a plurality of channels, a method for channel allocation comprising the steps of:

(a) receiving a request for channel allocation at one of the plurality of base stations from one of the at least one handset; and

(b) allocating one of the plurality of channels for the one of the at least one handset to communicate, the one of the plurality of channels allocated in accordance with a mean margin value of a plurality of measured margins of channel quality of the one of the plurality of channels in relationship to a predetermined threshold channel quality, and

wherein the step (b) of allocating one of the plurality of channels further comprises the steps of;

(d) comparing the plurality of channels on the basis of the mean margin value of each of the plurality of channels; and

(e) allocating one of the plurality of channels having a lower means margin value.

3. In a radio communication system comprising a plurality of base stations and at least one handset for communicating on a plurality of channels, a method for channel allocation comprising the steps of:

(a) receiving a request for channel allocation at one of the plurality of base stations from one of the at least one handset; and

(b) allocating one of the plurality of channels for the one of the at least one handset to communicate, the one of the plurality of channels allocated in accordance with a mean margin value of a plurality of measured margins of channel quality of the one of the plurality of channels in relationship to a predetermined threshold channel quality, and

wherein the step (b) of allocating one of the plurality of channels further comprises the steps of;

(f) comparing the plurality of channels on the basis of the mean margin value and a number of prior interrupted calls occurring on each of the plurality of channels; and

(g) allocating one of the plurality of channels in accordance with the one of the plurality of channels having a lower number of prior interrupted calls or a lower mean margin value.

4. In a radio communication system comprising a plurality of base stations and at least one handset for communicating on a plurality of channels, a method for channel allocation comprising the steps of:

(a) receiving a request for channel allocation at one of the plurality of base stations from one of the at least one handset; and

(b) allocating one of the plurality of channels for the one of the at least one handset to communicate, the one of the plurality of channels allocated in accordance with a mean margin value of a plurality of measured margins of channel quality of the one of the plurality of channels in relationship to a predetermined threshold channel quality, and

wherein the step (b) of allocating one of the plurality of channels further comprises the steps of;

(h) comparing the plurality of channels on the basis of the mean margin value, a number of prior successfully completed calls, a number of prior interrupted calls, and a number of prior blocked call setup requests occurring on each of the plurality of channels; and

(i) allocating one of the plurality of channels in accordance with the one of the plurality of channels having a lower mean margin value, a higher number of prior successfully completed calls, a lower number of prior interrupted calls, or a lower number of prior blocked call setup requests.

5. The method of claim 4 wherein the step (h) of allocating one of the plurality of channels further comprises the steps of:

(j) allocating one of the plurality of channels in response to the one of the plurality of channels having a best quality function wherein the quality function is an increasing function of the number of prior successfully completed calls and a current channel quality of the one of the plurality of channels, and wherein the quality function is a decreasing function of the mean margin value, the number of prior interrupted calls, and the number of prior blocked call setup requests.

6. In a radio communication system comprising a plurality of base stations and at least one handset for communicating on a plurality of channels, a method for channel allocation comprising the steps of:

(a) one of the plurality of base stations receiving a request for channel allocation from one of the at least one handset; and

(b) allocating one of the plurality of channels for the one of the at least one handset to communicate, the one of the plurality of base stations having assigned thereto a plurality of assigned channels, the plurality of assigned channels forming a subset of the plurality of channels, the one of the at least one channel allocated in response to determining whether the one of the plurality of channels is one of the plurality of assigned channels assigned to the one of the plurality of base stations and whether the one of the plurality of base stations is lightly loaded, the step (b) of allocating one of the plurality of assigned channels further comprising the steps of;

(c) determining whether the one of the plurality of base stations is lightly loaded; and

(d) allocating one of the plurality of assigned channels for the one of the at least one handset to communicate, the one of the plurality of assigned channels allocated from a predetermined portion of the plurality of assigned channels in response to determining that the one of the plurality of base stations is lightly loaded.

7. The method of claim 6 wherein the one of the plurality of base stations can allocated at least one borrowed channel, and wherein the step (d) of allocating one of the plurality of channels further comprises the steps of:

(e) determining whether the request for channel allocation requests one of the at least one borrowed channel of the one of the plurality of base stations; and

(f) allocating one of the at least one borrowed channel in response to determining that the request for channel allocation requests one of the at least one borrowed channel or allocating one of the plurality of assigned channels in response to determining that the request for channel allocation does not request one of the at least one borrowed channel.

8. The method of claim 6 further comprising the step of (g) borrowing one of the plurality of channels to have it become one of the at least one borrowed channel of the one of the plurality of base stations if all of the following conditions are met:

(1) the quality of the one of the plurality of channels is currently good,

(2) the one of the plurality of channels is not locally heavy loaded at the one of the plurality of base stations,

(3) the one of the plurality of channels is not one of the plurality of assigned channels, and

(4) the one of the plurality of channels has not been in use for a first predetermined period of time.

9. The method of claim 6 further comprising the step of (h) reassigning one of the plurality of channels to have it become one of the plurality of assigned channels of the one of the plurality of base stations if all of the following conditions are met:

(1) the one of the plurality of channels is not one of the plurality of assigned channels,

(2) the one of the plurality of channels is locally heavy loaded at the one of the plurality of base stations, and

(3) the one of the plurality of channels has a channel quality greater than or equal to a predetermined channel quality threshold for a second predetermined period of time.

10. The method of claim 6 further comprising the step of (i) readjusting an assignment of one of the plurality of assigned channels to have it deleted from the plurality of assigned channels of the one of the plurality of base stations if both of the following conditions are met;

(1) the one of the plurality of assigned channels is locally heavy loaded at the one of the plurality of base stations, and

(2) the quality of the one of the plurality of assigned channels is not good.

11. A radio communication system for communicating on a plurality of channels comprising:

at least one handset; and

a plurality of base stations, each of the plurality of base stations comprising;

control means for determining an order of said plurality of channels in response to a mean margin value of a plurality of measured margins of channel quality of each of the plurality of channels in relationship to a predetermined threshold channel quality;

memory means for storing a listing of the plurality of channels in the order determined by the control means;

input means for receiving a channel allocation request from one of said at least one handset; and

channel allocation means coupled to the input means and the memory means for allocating one of the plurality of channels in response to the channel allocation request, said one of the plurality of channels determined to be a next free channel in the listing stored in the memory means.

12. A radio communications system for communicating on a plurality of channels comprising:

at least one handset;

event detection means for detecting call interruptions;

a plurality of base stations, each of the plurality of base stations comprising;

control means for determining an order of said plurality of channels in response to a mean margin value of a plurality of measured margins of channel quality of each of the plurality of channels in relationship to a predetermined threshold channel quality and a number of the call interruptions on each of said plurality of channels;

memory means for storing a listing of the plurality of channels in the order determined by the control means;

input means for receiving a channel allocation request from one of said at least one handset; and

channel allocation means coupled to the input means and the memory means for allocating one of the plurality of channels in response to the channel allocation request, said one of the plurality of channels determined in the listing stored in the memory means.

13. The radio communication system of claim 12 wherein the event detection means further detects successfully completed calls and blocked call setup requests, and wherein the control means determines the order of said plurality of channels in response to the mean margin value of, the number of the call interruptions on, a number of the successfully completed calls on, and a number of the blocked call setup requests on each of the plurality of channels.

14. The radio communication system of claim 12 further comprising margin measurement means coupled to the event detection means for measuring a margin value of channel quality of each of the plurality of channels in relationship to a predetermined threshold channel quality upon each occurrence of the successfully completed calls, and wherein the control means is also coupled to the margin measurement means for updating the mean margin value upon each measurement of the margin value.

15. The radio communication system of claim 13 further comprising measurement means for measuring a current channel quality of each of the plurality of channels, and wherein the control means is also coupled to the measurement means for determining the order of said plurality of channels in response to the current channel quality of, the mean margin value of, the number of call interruptions on, a number of successfully completed calls on, and a number of blocked call setup requests on each of said plurality of channels.

16. A radio communications system for communicating on a plurality of channels comprising:

at least one handset; and

a plurality of base stations, each of the plurality of base stations having a plurality of assigned channels assigned thereto, the plurality of assigned channels forming a subset of the plurality of channels, each of the plurality of base stations comprising;

determining means for determining whether one of the plurality of channels is one of the plurality of assigned channels assigned thereto and for determining whether the one of the plurality of channels is locally heavy loaded or not;

control means for maintaining a list of the plurality of assigned channels;

input means for receiving a channel allocation request from one of said at least one handset, the input means comprising;

means for receiving the channel allocation request; and

means for determining whether the channel allocation request requests an assigned channel or a borrowed channel; and

channel allocation means coupled to the input means and the determining means for allocating one of the plurality of channels in response to the channel allocation request, the one of the plurality of channels determined to be one of the at least one borrowed channel in response to the input determining means determining that the channel allocation request requests a borrowed channel or determined to be one of the plurality of assigned channels in response to determining that the channel allocation request does not request one of the at least one borrowed channel.

17. The radio communications system of claim 16 wherein each of the plurality of base stations further comprises a quality measuring means for measuring whether a channel quality of the plurality of channels is good, and wherein the control means adds one of the plurality of channels to the list of the at least one borrowed channel if the quality measuring means determines the channel quality of the one of the plurality of channels is good, if the determining means determines that the one of the plurality of channels is not locally heavy loaded, and if the control means determines the one of the plurality of channels is not one of the plurality of assigned channels, and if the control means determines the one of the plurality of channels has not been in use for a first predetermined period of time.

18. A radio communications system for communicating on a plurality of channels comprising:

at least one handset; and

a plurality of base stations, each of the plurality of base stations having a plurality of assigned channels assigned thereto, the plurality of assigned channels forming a subset of the plurality of channels, each of the plurality of base stations comprising;

determining means for determining whether one of the plurality of channels is one of the plurality of assigned channels assigned thereto and for determining whether the one of the plurality of channels is locally heavy loaded or not;

quality measuring means for measuring whether a channel quality of the plurality of channels is good;

control means for maintaining a list of the plurality of assigned channels, wherein the control means adds one of the plurality of channels to the list of the plurality of assigned channels if the determining means determines that the one of the plurality of channels is locally heavy loaded, if the control means determines the one of the plurality of channels is not one of the plurality of assigned channels, and if the quality measuring means determines the channel quality of the one of the plurality of channels is greater than or equal to a predetermined channel quality threshold for a second predetermined period of time;

input means for receiving a channel allocation request from one of said at least one handset; and

channel allocation means coupled to the input means and the determining means for allocating one of the plurality of channels in response to the channel allocation request, the one of the plurality of channels determined in response to whether said one of the plurality of channels is one of the plurality of assigned channels and whether the one of the plurality of base stations is lightly loaded.

19. The radio communications system of claim 18 wherein the control means removes one of the plurality of assigned channels from the list of the plurality of assigned channels if the determining means determines that the one of the plurality of channels is locally heavy loaded and if the quality measuring means determines the channel quality of the one of the plurality of channels is not good.