Self-configurable wireless systems: spectrum monitoring in a layered configuration
First Claim
1. A method for coordinating RF use in primary and adjunct wireless systems which are layered in a common geographic area, the adjunct system shielded from interference from the primary system, and which share the same RF spectrum, wherein the adjunct system includes adjunct base stations defining respective adjunct wireless cells and serving adjunct mobile stations located within the respective adjunct cell and the primary system includes primary base stations defining respective primary wireless cells and serving primary mobile stations located within the primary wireless cell, comprising:
- monitoring all RF channels by the adjunct system and partitioning unused frequencies by the primary system into two sets, a set of channels likely to be interference-free and a set of noisy channels;
forming a pool of interference-free channels for use by all adjunct base stations;
assigning channels to adjunct cells from the interference-free set;
grouping interference-free channels left unassigned as back-up channels in case the assigned channels become noisy;
during an operation phase, performing sequential tests of the channel, wherein an analysis of the noise or interference signal strength is made after each individual measurement;
if the noise or interference signal strength is detected above a specified threshold, then the channel is immediately reclassified as noisy; and
if a channel currently classified as noisy has a detected noise or interference signal strength below a specified threshold, then a stopping criterion interval is checked, wherein if the time expired since the first low-noise measurement is less than the stopping criterion interval, then a sampling of additional measurements of the channel are made before changing the classification to interference-free, wherein the magnitude of the stopping criterion interval and the sample size for low signal-strength measurements are based on an error probability analysis.
1 Assignment
0 Petitions
Accused Products
Abstract
A method and system are disclosed for coordinating RF use in primary and adjunct wireless systems which are overlapped or layered in a common geographic area and which share the same the same RF spectrum. The adjunct system includes adjunct base stations defining respective adjunct wireless cells and serving adjunct mobile stations located within the respective adjunct cell. The primary system includes primary base stations defining respective primary wireless cells and serving primary mobile stations located within the primary wireless cell. The adjunct base stations monitor all RF channels and partition them into two sets, a set of channels likely to be interference-free and a set of noisy channels. Once control channels have been assigned to the base stations, the adjunct mobile stations may also participate in the monitoring step by employing the MAHO/MACA features of the IS 136 or GSM Air Interface Standard. The adjunct system forms a pool of interference-free channels for use by all adjunct base stations and mobiles. Channels are assigned to the adjunct base stations from the interference-free set. The interference-free channels left unassigned serve as back-up channels for period replacement of the assigned channels and in case the assigned channels become noisy. A channel not being used by the adjunct system is an nonassigned channel. The spectrum monitoring procedure by the adjunct base stations for nonassigned channels measures received signal strength. If a channel has a strong signal above a predetermined threshold, then it is deemed noisy. If a channel has a weak signal strength, then the adjunct base stations must deduce the likelihood of future interference caused by activity in nearby cells in the primary system. During the operation phase, each adjunct base station, in conjunction with mobile units in its respective adjunct cell, continually monitor the channels and their classification is updated if there is a change in the background noise or in the interference signal strength indicating a change spectrum use by the primary system.
88 Citations
12 Claims
-
1. A method for coordinating RF use in primary and adjunct wireless systems which are layered in a common geographic area, the adjunct system shielded from interference from the primary system, and which share the same RF spectrum, wherein the adjunct system includes adjunct base stations defining respective adjunct wireless cells and serving adjunct mobile stations located within the respective adjunct cell and the primary system includes primary base stations defining respective primary wireless cells and serving primary mobile stations located within the primary wireless cell, comprising:
-
monitoring all RF channels by the adjunct system and partitioning unused frequencies by the primary system into two sets, a set of channels likely to be interference-free and a set of noisy channels;
forming a pool of interference-free channels for use by all adjunct base stations;
assigning channels to adjunct cells from the interference-free set;
grouping interference-free channels left unassigned as back-up channels in case the assigned channels become noisy;
during an operation phase, performing sequential tests of the channel, wherein an analysis of the noise or interference signal strength is made after each individual measurement;
if the noise or interference signal strength is detected above a specified threshold, then the channel is immediately reclassified as noisy; and
if a channel currently classified as noisy has a detected noise or interference signal strength below a specified threshold, then a stopping criterion interval is checked, wherein if the time expired since the first low-noise measurement is less than the stopping criterion interval, then a sampling of additional measurements of the channel are made before changing the classification to interference-free, wherein the magnitude of the stopping criterion interval and the sample size for low signal-strength measurements are based on an error probability analysis. - View Dependent Claims (2, 3, 4)
monitoring active assigned channels through measurement of the serving signal strength and the bit-error rate, and if a channel has a strong signal and a high bit-error rate, then it is classified as noisy and is replaced by a back-up channel, and if a channel has a weak signal and a high bit-error rate, then a hand-off is made to an adjacent adjunct cell;
and monitoring all assigned channels by replacing each with a back-up channel which is monitored as an nonassigned channel; and
monitoring nonassigned channels through measurement of background noise strength, and if a channel has a strong background noise above a predetermined threshold, then it is classified noisy, and if a channel has a weak background noise, then determining a likelihood of interference caused by activity in nearby cells in the primary system by measurements of the channel obtained over the entire adjunct system and selecting a strongest measurement, and if it exceeds a specified threshold, then the channel is classified noisy, otherwise it is classified interference-free.
-
-
3. The method of claim 2, which further comprises:
during an initialization phase, performing a series of consecutive uplink and downlink measurements of a channel having a sample size N over a testing interval, the magnitude of the sample size and testing interval being based on an error probability analysis.
-
4. The method of claim 3, which further comprises:
during an operation phase, continually monitoring the channels and updating their classification if there is a change in the background noise or in spectrum use by the primary system.
-
5. A system for coordinating RF use in primary and adjunct wireless systems which are layered in a common geographic area, the adjunct system shielded from interference from the primary system, and which share the same RF spectrum, wherein the adjunct system includes adjunct base stations defining respective adjunct wireless cells and serving adjunct mobile stations located within the respective adjunct cell and the primary system includes primary base stations defining respective primary wireless cells and serving primary mobile stations located within the primary wireless cell, comprising:
-
an RF monitor in an adjunct base station monitoring all RF channels and partitioning frequencies unused by the primary system into two sets, a set of channels likely to be interference-free and a set of noisy channels;
a processor in the adjunct base station forming a pool of interference-free channels for use by all adjunct base stations;
said processor assigning channels to adjunct cells from the interference-free set;
said processor grouping interference-free channels left unassigned as back-up channels in case the assigned channels become noisy;
during an operation phase, said processor performing sequential tests of the channel, wherein an analysis of the noise or interference signal strength is made after each individual measurement;
if the noise or interference signal strength is detected above a specified threshold, then the channel is immediately reclassified as noisy; and
if a channel currently classified as noisy has a detected noise or interference signal strength below a specified threshold, then a stopping criterion interval is checked, wherein if the time expired since the first low-noise measurement is less than the stopping criterion interval, then a sampling of additional measurements of the channel are made before changing the classification to interference-free, wherein the magnitude of the stopping criterion interval and the sample size for low signal-strength measurements are based on an error probability analysis. - View Dependent Claims (6, 7, 8, 9, 10)
said RF monitor monitoring active assigned channels through measurement of the serving signal strength and the bit-error rate, and if a channel has a strong signal and a high bit-error rate, then it is classified as noisy and is replaced by a back-up channel, and if a channel has a weak signal and a high bit-error rate, then a hand-off is made to an adjacent adjunct cell, and and monitoring all assigned channels by replacing each with a back-up channel which is monitored by said RF monitor as an nonassigned channel; and
said RF monitor monitoring nonassigned channels through measurement of background noise and interference signal strength, and if a channel has a strong background signal above a predetermined threshold, then it is classified noisy, and if a channel has a weak background signal, then determining a likelihood of interference caused by activity in nearby cells in the primary system by measurements of the channel obtained over the entire adjunct system and selecting a strongest measurement, and if it exceeds a specified threshold, then the channel is classified noisy, otherwise it is classified interference-free.
-
-
7. The system of claim 6, which further comprises:
during an initialization phase, said processor performing a series of consecutive measurements of a channel over the entire adjunct system having a sample size N over a testing interval, and selecting a strongest measurement, and if it exceeds a specified threshold, then the channel is classified noisy, otherwise it is classified interference-free, wherein the magnitude of the sample size and testing interval being based on an error probability analysis.
-
8. The system of claim 7, which further comprises:
during an operation phase, said processor continually monitoring the channels and updating their classification if there is a change in the background noise or in spectrum use by the primary system.
-
9. The method of claim 5, which further comprises:
said RF monitor at the adjunct base station consists of the base station receiver which is capable of tuning to both up-link and down-link frequencies.
-
10. The method of claim 5, which further comprises:
said processor at the adjunct base station coordinates signal strength measurements which are made by the mobile stations served by said adjunct base station, utilizing the MAHO/MACA features of the IS 136 or GSM Air Interface Standard, to be employed for spectrum monitoring purposes in conjunction with measurements made by said RF monitor located at the adjunct base station.
-
11. A method for coordinating RF use in primary and adjunct wireless systems which are layered in a common geographic area, the adjunct system shielded from interference from the primary system, and which share the same RF spectrum, wherein the adjunct system includes adjunct base stations defining respective adjunct wireless cells and serving adjunct mobile stations located within the respective adjunct cell and the primary system includes primary base stations defining respective primary wireless cells and serving primary mobile stations located within the primary wireless cell, comprising:
-
monitoring all RF channels by the adjunct system and partitioning unused frequencies by the primary system into two sets, a set of channels likely to be interference-free and a set of noisy channels;
forming a pool of interference-free channels for use by all adjunct base stations;
assigning channels to adjunct cells from the interference-free set;
grouping interference-free channels left unassigned as back-up channels in case the assigned channels become noisy;
during an operation phase, performing sequential tests of the channel at random time spacing between consecutive measurements, wherein an analysis of the noise or interference signal strength is made after each individual measurement;
if the noise or interference signal strength is detected above a specified threshold, then the channel is immediately reclassified as noisy; and
if a channel currently classified as noisy has a detected noise or interference signal strength below a specified threshold, then a stopping criterion is checked, wherein if the value of a statistic that depends on the realized sampling spacing time intervals is checked and if it exceeds a specified constant, then a sampling of additional measurements of the channel are made before changing the classification to interference-free, wherein the magnitude of the stopping constant are based on an error probability analysis.
-
-
12. A system for coordinating RF use in primary and adjunct wireless systems which are layered in a common geographic area, the adjunct system shielded from interference from the primary system, and which share the same RF spectrum, wherein the adjunct system includes adjunct base stations defining respective adjunct wireless cells and serving adjunct mobile stations located within the respective adjunct cell and the primary system includes primary base stations defining respective primary wireless cells and serving primary mobile stations located within the primary wireless cell, comprising:
-
an RF monitor in an adjunct base station monitoring all RF channels and partitioning frequencies unused by the primary system into two sets, a set of channels likely to be interference-free and a set of noisy channels;
a processor in the adjunct base station forming a pool of interference-free channels for use by all adjunct base stations;
said processor assigning channels to adjunct cells from the interference-free set;
said processor grouping interference-free channels left unassigned as back-up channels in case the assigned channels become noisy;
during an operation phase, said processor performing sequential tests of the channel at random time spacing between consecutive measurements, wherein an analysis of the noise or interference signal strength is made after each individual measurement;
if the noise or interference signal strength is detected above a specified threshold, then the channel is immediately reclassified as noisy; and
if a channel currently classified as noisy has a detected noise or interference signal strength below a specified threshold, then a stopping criterion is checked, wherein if the value of a statistic that depends on the realized sampling spacing time intervals is checked and if it exceeds a specified constant, then a sampling of additional measurements of the channel are made before changing the classification to interference-free, wherein the magnitude of the stopping constant are based on an error probability analysis.
-
Specification