Dynamic channel assignment cordless telecommunication network

• US 5,363,428 A
• Filed: 05/18/1992
• Issued: 11/08/1994
• Est. Priority Date: 05/17/1991
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Nagashima, Noriaki
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Cumming, William D.
• Application Number:
  US07/884,154
• Time in Patent Office: 904 Days
• Field of Search: 379/56, 379/58, 379/59, 379/60, 379/61, 455/9, 455/17, 455/33.1, 455/34.1, 455/56.1
• US Class Current: 455/452.1
• CPC Class Codes: H04W 72/54 based on quality criteria
• CPC Class Codes: H04W 72/56 based on priority criteria
• CPC Class Codes: H04W 76/10 Connection setup

Abstract

In a microcellular cordless telephone network, radio speech channels are divided into several channel groups such that no intermodulation products occur among the channels of each group. In each microcell is located a base unit to which one of the channel groups is dynamically assigned. To achieve the channel assignment, each base unit generates priority values of the channel groups as representations of usage of the channel groups, consistently updates them through a statistical process and assigns one of the channel groups having a maximum priority value to the base unit.

Claims

1. A telecommunication network for serving cordless units located in a plurality of service zones, said network having radio speech channels which are organized into a plurality of channel groups such that no intermodulation products occur among the channels of each group, said network comprising a plurality of base units located respectively in said service zones, each of said base units comprising:

means for establishing two-way speech channels with those of the cordless units which are located in the same zone as the base unit;

a priority table for storing priority values of said channel groups;

means for detecting a maximum priority value from said priority table at periodic intervals and assigning one of said channel groups having the detected priority value to the base unit; and

means for (a) measuring field intensity of each of said radio channels, classifying the measured field intensity of each channel as representing first, second or third possible states, (b) determining whether all the measured field intensities simultaneously represent a mixture of said first, second and third possible states, (c) increasing the priority value of the assigned channel group if the measured field intensity of each channel is classified as representing the third possible state and all the measured field intensities are determined as representing said mixture of possible states, and (d) decreasing the priority value of the assigned channel group if the measured field intensity of each channel is classified as representing the first or second possible state and all the measured field intensities are determined as representing said mixture of possible states, said first, second and third possible states representing respectively an idle state of a channel, a busy state of a channel of the assigned channel group, and a busy state of a channel of a channel group other than the assigned channel group.

6. A telecommunication network as claimed in claim 1, further comprising a local switching system connected to a public switched telecommunication network, wherein said base units are connected to said local switching system.

2. A telecommunication network for serving cordless units located in a plurality of service zones, said network having radio speech channels which are organized into a plurality of channel groups such that no intermodulation products occur among the channels of each group, said network comprising a plurality of base units located respectively in said service zones, each of said base units comprising:

means for establishing two-way speech channels with those of the cordless units which are located in the same zone as the base unit;

a priority table for storing priority values of said channel groups;

means for detecting a maximum priority value from said priority table and assigning one of the channel groups having the detected priority value to the base unit;

means for (a) measuring field intensity of each of said radio speech channels, classifying the measured field intensity of each channel as representing first, second or third possible states of the channel, (b) determining whether all the measured field intensities simultaneously represent a mixture of said first, second and third possible states of said channels, (c) increasing the stored priority value of the assigned channel group if the measured field intensity of each channel is classified as representing the third possible state and all the measured field intensities are determined as representing said mixture of possible states, and (d) decreasing said stored priority value of the assigned channel group if the measured field intensity of each channel is classified as representing the first or second possible state and all the measured field intensities are determined as representing said mixture of possible states, said first, second and third possible states representing respectively an idle state of each channel, a busy state of each channel of the channel group currently assigned to the base unit, and a busy state of a channel of a channel group other than the assigned channel group;

means for detecting a maximum priority value from said priority table; and

means for comparing the detected maximum priority value with the priority value of the assigned channel group and reassigning one of said channel groups having said maximum priority value instead of the current channel group if the maximum priority value is greater than the priority value of the current channel group by more than a predetermined amount.

3. A telecommunication network for serving cordless units located in a plurality of service zones, said network having radio speech channels which are organized into a plurality of channel group such that no intermodulation products occur among the channels of each group, said network comprising a plurality of base units located respectively in said service zones, each of said base units comprising:

means for establishing two-way speech channels with those of the cordless units which are located in the same zone as the base unit;

priority table for storing priority values of said channel groups;

means for detecting a maximum priority value from said priority table and assigning one of said channel groups having the detected priority value to the base unit;

a channel status table for storing busy/idle status bits indicating the busy/idle states of said channels;

means for receiving a call request to or from said cordless units located in the same zone as the base unit, and updating the busy/idle status bits of the channels of the assigned channel group; and

means for (a) sequentially retrieving all the busy/idle status bits from said channel status table, (b) classifying each channel of all said groups as representing a first possible state of the channel if the retrieved status bit indicates a busy state of the channel, (c) measuring field intensity of each channel of all said groups if the retrieved status bit indicates an idle or busy state of the channel and classifying the channel as representing a second possible state if the measured field intensity of the channel is lower than a specified value or a third possible state of the channel if the measured field intensity is higher than the specified value, (d) determining whether all the channels are classified as simultaneously representing a mixture of said first, second and third possible states, (e) increasing the stored priority value of the assigned channel group if each channel of all said groups is classified as representing the third possible state and all channels of said groups are determined as representing said mixture of said possible states and (f) decreasing said stored priority value of the assigned channel group if each channel of all said groups is classified as representing the first or second possible state and all channels of said groups are determined as representing said mixture of said possible states, said third possible state representing a busy state of each channel of a channel group other than said assigned channel group.

4. A telecommunication network as claimed in claim 3, wherein said maximum value detecting and assigning means comprises means for retrieving the busy/idle status bits of the channels of the assigned group, detecting a maximum priority value subsequently from the priority table, and reassigning the channel group having the subsequently detected maximum priority value to the base unit if the retrieved status bits indicate all idle states.

5. A telecommunication network for serving cordless units located in a plurality of service zones, said network having radio speech channels which are organized into a plurality of channel groups such that no intermodulation products occur among the channels of each group, said network comprising a plurality of base units located respectively in said service zones, each of said base units comprising:

means for establishing two-way speech channels with those of the cordless units which are located in the same zone as the base unit;

priority table for storing priority values of said channel groups;

means for detecting a maximum priority value from said priority table and assigning one of channel groups having the detected priority value to the base unit;

a channel status table for storing busy/idle status bits indicating the busy/idle states of said channels;

means for receiving a call request to or from said cordless units located in the same zone as the base unit, and updating the busy/idle status bits of the channels of the assigned channel group;

means for (a) sequentially retrieving all the busy/idle status bits from said channel status table, (b) classifying each channel of all said groups as representing a first possible state of the channel if the retrieved status bit indicates a busy state of the channel, (c) measuring field intensity of each channel of all said groups if the retrieved status bit indicates an idle or busy state of the channel and classifying the channel as representing a second possible state of the channel if the measured field intensity of the channel is lower than a specified value or a third possible state of the channel if the measured field intensity is higher than the specified value, (d) determining whether all the channels are classified as simultaneously representing a mixture of said first, second and third possible states, (e) increasing the priority value of the assigned channel group if each channel of all said groups is classified as representing the third possible state and if all channels of said groups are determined as representing said mixture of said possible states, and (f) decreasing said stored priority value of the currently assigned channel group if each channel of all said groups is classified as representing the first or second possible state and if all channels of said groups are determined as representing said mixture of said possible states, said third possible state representing a busy state of each channel of a channel group which is not currently assigned to the base unit;

means for comparing the increased priority value with the priority value of the assigned channel group and reassigning one of said channel groups having said increased priority value instead of the current channel group if the increased priority value is greater than the priority value of the current channel group by more than a predetermined amount.

7. In a telecommunication network for serving cordless units located in a plurality of service zones, said network having radio speech channels which are organized into a plurality of channel groups such that no intermodulation products occur among the channels of each group, said network comprising a plurality of base units located respectively in said service zones, each of said base units comprising means for establishing two-way speech channels with those of the cordless units which are located in the same zone as the base unit, and a priority table for storing priority values of said channel groups, a method for assigning one of said channel groups to each one of said base units comprising the steps of:

a) detecting a maximum priority value from the priority table and assigning one of said channel groups having the detected maximum priority value to the base unit;

b) measuring field intensity of each of said radio channels;

c) classifying the measured field intensity of each channel as representing first, second or third possible states of the channel;

d) determining whether all the measured field intensities simultaneously represent a mixture of said first, second and third possible states, said first, second and third possible states representing respectively an idle state of each channel, a busy state of each channel of the assigned channel group, and a busy state of each channel of a channel group other than the assigned channel group; and

e) if all measured field intensities are determined by the step (d) as representing said mixture of said possible sates, increasing the priority value of the assigned channel group if the measured field intensity of each channel is classified by the step (c) as representing the third possible state and decreasing the priority value of the assigned channel group if the measured field intensity of each channel is classified by the step (c) as representing the first or second possible state.

9. A method as claimed in claim 7, further comprising the steps of:

1) detecting a maximum priority value from said priority table;

2) comparing the maximum priority value detected by the step (1) with the priority value of a channel group currently assigned to the base unit; and

3) reassigning one of the channel groups having the maximum priority value detected by the step (1) to the base unit if the priority value detected by the step (1) is greater than the priority value of the currently assigned channel group.

8. In a telecommunication network for serving cordless units located in a plurality of service zones, said network having radio speech channels which are organized into a plurality of channel groups such that no intermodulation products occur among the channels of each group, said network comprising a plurality of base units located respectively in said service zones, each of said base units comprising means for establishing two-way speech channels with those of the cordless units which are located in the same zone as the base unit, a priority table for storing priority values of said channel groups, and a channel status table for storing busy/idle status bits indicating the busy/idle states of said channels, a method for assigning one of said channel groups to each one of said base units comprising the steps of:

a) detecting a maximum priority value from the priority table and assigning one of said channel groups having the detected maximum priority value to the base unit;

b) receiving a call request to or from said cordless units located in the same zone as the base unit, and updating the busy/idle status bits of the channels of the assigned channel group;

c) sequentially retrieving all the busy/idle status bits from said channel status table;

d) classifying each channel of all said groups as representing a first possible state of the channel if the retrieved status bit indicates a busy state of the channel;

e) measuring field intensity of each channel of all said groups if the retrieved status bit indicates an idle busy state of the channel and classifying the channel as representing a second possible state of the channel if the measured field intensity of the channel is lower than a specified value or a third possible state of the channel if the measured field intensity is higher than the specified value, said third possible state representing a busy state of each channel of a channel group other than the assigned channel group;

f) determining whether all the channels of said groups are classified sa simultaneously representing a mixture of said first, second and third possible states; and

g) if all channels of said groups are determined by the step (f) as representing said mixture of said possible states, increasing the priority value of the assigned channel group if each channel of all said groups is classified by the step (d) as representing the third possible state, and decreasing the priority value of the assigned channel group if each channel of all said groups is classified by the step (d) as representing the first or second possible state.

10. A method as claimed in claim 8, further comprising the steps of:

1) detecting a maximum priority value from said priority table;

2) comparing the maximum priority value detected by the step (1) with the priority value of a channel groups currently assigned to the base unit; and

3) reassigning one of the channel groups having the maximum priority value detected by the step (1) to the base unit if the priority value detected by the step (1) is greater than the priority value of the currently assigned channel group.