Method for allocating channel resources for improving frequency utilization efficiency of wireless communication systems

• US 7,634,277 B2
• Filed: 08/16/2005
• Issued: 12/15/2009
• Est. Priority Date: 04/28/2005
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Grabner, John, Jin, Hang
• Primary Examiner(s): Eng; George
• Assistant Examiner(s): Brandt; Christopher M
• Application Number:
  US11/204,493
• Publication Number:
  US 20060246917A1
• Time in Patent Office: 1,582 Days
• Field of Search: 455/450, 455/453, 455/447, 455/449, 455/451, 455/452.1, 455/452.2, 455/446, 455/509, 370/322, 370/328, 370/329, 370/330, 370/331, 370/338, 370/341, 370/348
• US Class Current: 455/452.2
• CPC Class Codes: H04W 16/02 Resource partitioning among network components, e.g. reuse partitioning
• 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 28/16 Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]

Abstract

A method for improving a frequency utilization efficiency for a wireless communication system having a plurality of cells includes the following steps. At least one primary channel is allocated for each cell, the primary channel being different from that of its neighboring cell. One or more secondary channels are allocated for each cell, which have the same frequencies as their corresponding primary channels but differ in configuration, the secondary channels being different in frequency from the primary channel of the same cell. The secondary channel of the cell is activated for carrying communication traffic when the primary channel of the same cell has a capacity of being used exceeding a predetermined threshold value.

Claims

1. A method comprising:

at a base station that serves a corresponding cell in a wireless communication network comprising a plurality of cells, allocating at least one primary channel such that the primary channel of the cell is different from that of its neighboring cell served by another base station;

at the base station, allocating one or more secondary channels for its cell, wherein each of the one or more secondary channels for respective ones of the plurality of cells is associated with a corresponding primary channel and has the same frequency as its corresponding primary channel, and wherein within the cell the frequency of the secondary channel is different from the frequency of the primary channel;

at the base station, receiving from at least one terminal that it serves a channel performance report indicating performance on the secondary channel, and an indication of actual usage of the secondary channel and interference on the secondary channel;

at the base station, generating a merit score for its secondary channel based on the channel performance report received from the at least one terminal and actual usage on the secondary channel, wherein generating the merit score comprises generating over a period of time that is longer than a transmission frame length, a first value representing actual usage of the secondary channel as measured by the at least one terminal and a second value representing an amount of time that performance on the secondary channel is poor based on the channel performance report; and

at the base station, determining whether to activate the secondary channel based on a comparison of the first and second values with a threshold.

2. The method of claim 1, wherein allocating one or more secondary channels for each cell further comprises designating a channel that is a primary channel for a first cell as a secondary channel for a second cell based on one or more predetermined factors.

3. The method of claim 2, wherein the predetermined factors comprise a geographical distance between the first cell and the second cell.

4. The method of claim 2, wherein the predetermined factors comprise a level of isolation between the first cell and the second cell.

5. The method of claim 2, wherein the predetermined factors comprise a carrier-to-interference ratio for co-channel and adjacent channel interference as between the first cell and the second cell.

6. The method of claim 2, wherein the predetermined factors comprise heuristic data of system performance when the secondary channel in the second cell is activated for carrying the communication traffic.

7. The method of claim 1, wherein the secondary channel has a maximum transmit power lower than a maximum transmit power of its corresponding primary channel.

8. The method of claim 1, and further comprising, at the base station, comparing the first value with a first threshold and comparing a ratio of the second value to the first value with a second threshold, and wherein determining comprises determining not to activate the secondary channel for the at least one terminal for a period of time when the first value exceeds the first threshold and the ratio exceeds the second threshold.

9. The method of claim 1, and further comprising, at the base station, employing a power control scheme in the secondary channel of its cell that differs from the power control scheme used in the corresponding primary channel such that a power decrease rate is greater than a power increase rate in the secondary channel.

10. The method of claim 8, wherein when the first and second values are such that the secondary channel should be considered for activation for the at least one terminal, further comprising, at the base station, comparing downlink interference on the secondary channel with a downlink interference threshold and comparing uplink interference on the secondary channel with an uplink interference threshold, and wherein determining further comprises determining not to activate the secondary channel for the at least one terminal when the downlink interference exceeds the downlink interference threshold or the uplink interference exceeds the uplink interference threshold, and otherwise generating the merit score for the secondary channel comprises computing a sum of a first weighted difference between the uplink interference and the uplink interference threshold and a second weighted difference between the downlink interference and the downlink interference threshold.

11. The method of claim 1, wherein at the base station, employing a coding scheme for its secondary channel that is stronger than a coding scheme used for its corresponding primary channel.

12. The method of claim 1, wherein at the base station, employing a modulation scheme for its secondary channel that is lower than a modulation scheme used for its corresponding primary channel.

13. A method comprising:

at a base station that serves a corresponding cell in a wireless communication network comprising a plurality of cells, allocating at least one primary channel such that the primary channel of the cell is different from that of its neighboring cell served by another base station;

at the base station, allocating one or more secondary channels for its cell, wherein each of the one or more secondary channels for respective ones of the plurality of cells is associated with a corresponding primary channel and has the same frequency as its corresponding primary channel, and wherein within the cell the frequency of the secondary channel is different from the frequency of the primary channel, wherein allocating comprises designating a channel that is a primary channel for a first cell served by the base station as a secondary channel for a second cell served by another base station based on one or more predetermined factors comprising at least one of;

a geographical distance between the first cell and the second cell, a level of isolation between the first cell and the second cell, and a carrier-to-interference ratio for co-channel and adjacent channel interference as between the first cell and the second cell; and

at the base station, receiving from at least one terminal that it serves a channel performance report indicating performance on the secondary channel and an indication of actual usage of the secondary channel and interference on the secondary channel;

at the base station, generating a merit score for its secondary channel based on the channel performance report received from the at least one terminal, and actual usage on the secondary channel, wherein generating the merit score comprises generating over a period of time that is longer than a transmission frame length, a first value representing actual usage of the secondary channel as measured by the at least one terminal and a second value representing an amount of time that performance on the secondary channel is poor based on the channel performance report;

at the base station, determining whether to activate the secondary channel based on a comparison of the first and second values with a threshold.

14. The method of claim 13, and further comprising, at the base station, comparing the first value with a first threshold and comparing a ratio of the second value to the first value with a second threshold, and wherein determining comprises determining not to activate the secondary channel for the at least one terminal for a period of time when the first value exceeds the first threshold and the ratio exceeds the second threshold.

15. The method of claim 14, wherein when the first and second values are such that the secondary channel should be considered for activation for the at least one terminal, further comprising, at the base station, comparing downlink interference on the secondary channel with a downlink interference threshold and comparing uplink interference on the secondary channel with an uplink interference threshold, and wherein determining further comprises determining not to activate the secondary channel for the at least one terminal when the downlink interference exceeds the downlink interference threshold or the uplink interference exceeds the uplink interference threshold, and otherwise generating the merit score for the secondary channel comprises computing a sum of a first weighted difference between the uplink interference and the uplink interference threshold and a second weighted difference between the downlink interference and the downlink interference threshold.

16. The method of claim 13, wherein at the base station, employing a coding scheme for its secondary channel that is stronger than that a coding scheme used for its corresponding primary channel and using a modulation scheme for its secondary channel that is lower than a modulation scheme used for its corresponding primary channel.

17. The method of claim 13, and further comprising, at the base station, employing a power control scheme in the secondary channel of its cell that differs from the power control scheme used in the corresponding primary channel such that a power decrease rate is greater than a power increase rate in the secondary channel.