Interference mitigation in WLAN/WPAN co-existence networks
This invention generally relates to interference mitigation, and more specifically to interference mitigation in wireless communications networks. The proposed solution takes advantage of the clear channel assessment (CCA) function used by WLAN networks. Hence, by jamming the interfering WLAN channel during a predetermined time period, the interfering WLAN network is forced to withhold transmissions on the WLAN interfering channel during a backoff period of time. The solution of the subject application makes use of this backoff period to enable a WPAN network to transmit critical information such as, but not limited to, a request for changing the current working frequency.
1. A wireless personal area network, WPAN, node operating on a first WPAN channel and adapted to provide interference mitigation, the interference originating from a wireless local area network, WLAN, using a clear channel assessment, CCA, function to cause the WLAN to transmit, the WLAN operating on a WLAN channel having a bandwidth greater than the first WPAN channel bandwidth, the wireless network node comprising:
an interference detector adapted to generate an interference indicator upon detection of an interfering signal in the first WPAN channel;
at least one transmitter adapted to transmit a jamming signal; and,
a processor operably coupled to the interference detector and the transmitter, the processor being adapted to operate in at least one of:
a normal mode in which the processor is configured to determine whether an interference indicator is greater than a given interference threshold; and,
a mitigation mode, operable when the interference indicator is greater than the given interference threshold, in which the processor is configured to:
generate the jamming signal; and,
determine one neighbouring second WPAN channel different from the first WPAN channel, based on at least the interference indicator, the second WPAN channel being at least partly comprised within the WLAN channel bandwidth; and,
instruct the transmitter to continuously transmit the jamming signal in the second WPAN channel during a predetermined time period, at a given output power level sufficiently high so that the CCA function on the WLAN does not temporarily cause the WLAN to transmit on the WLAN channel.
2. The wireless network node of claim 1 , wherein the processor is configured to operate:
concurrently, in the normal mode and the mitigation mode; or,
alternatively, in the normal mode and the mitigation mode, wherein the processor switches from the mitigation mode to the normal mode after the predetermined time period has elapsed.
3. An interference mitigation system for providing interference mitigation in a wireless personal area network, WPAN, operating on a first WPAN channel, the interference originating from a wireless local area network, WLAN, using a clear channel assessment, CCA, function to cause the WLAN to transmit, the WLAN operating on a WLAN channel having a bandwidth greater than the first WPAN channel bandwidth, the system comprising:
one or more wireless network nodes, WNN, according to claim 1 wherein one WNN is a wireless network node manager, WNNM;
wherein:
the WNN are configured to inform the WNNM when an interference indicator is greater than a given interference threshold;
the processor of the WNNM is adapted to, upon being informed by the WNN:
determine at least one neighbouring second WPAN channel different from the first WPAN channel, based on at least the interference indicator, the second WPAN channel being at least partly comprised within the WLAN channel bandwidth; and,
instruct the WNN, based on a given mitigation strategy, while being in the mitigation mode, to continuously transmit a jamming signal in the second WPAN channel during a predetermined time period, at a given output power level sufficiently high so that the CCA function on the WLAN does not temporarily cause the WLAN to transmit on the WLAN channel.
4. The system of claim 3 , wherein the mitigation strategy is at least one of:
one or more WNN are instructed to transmit concurrently on the same second WPAN channel; and,
one WNN is instructed to transmit on one second WPAN channel.
5. The system of claim 3 , wherein the second WPAN channel is adjacent to the first WPAN channel.
6. The system of claim 3 , wherein when the processor operates alternatively in the normal mode and the mitigation mode:
before the processor of a first WNN switches to the mitigation mode, the processor of the first WNN is configured to instruct at least one processor of a second WNN to receive data directed to the first WNN; and,
during the predetermined time period wherein the first WNN is in the mitigation mode, the processor of the second WNN is adapted to store in a memory received data originally directed to the first WNN.
7. The system of claim 3 wherein when the processor operates alternatively in the normal mode and the mitigation mode:
before the processor of a first WNN switches to the mitigation mode, the processor of the first WNN is configured to request the WNNM to instruct at least one processor of second WNN to receive data directed to the first WNN; and,
during the predetermined time period wherein the first WNN is in the mitigation mode, the processor of the second WNN is adapted to store the received data originally directed to the first WNN.
8. The system of claim 3 wherein the WNNM is configured to increase or shorten the predetermined time period.
9. A method of providing interference mitigation in a wireless personal area network, WPAN, operating on a first WPAN channel, the interference originating from a wireless local area network, WLAN, using a clear channel assessment, CCA, function to cause the WLAN to transmit, the WLAN operating on a WLAN channel having a bandwidth greater than the first WPAN channel bandwidth, the method comprising:
providing one or more wireless network nodes, WNN;
determining one wireless network node manager, WNNM, out of the WNN;
wherein the method comprises:
operating the WNN to inform the WNNM when an interference indicator is greater than a given interference threshold;
operating the processor of the WNNM to:
determine at least one neighbouring second WPAN channel different from the first WPAN channel, based on the interference indicator, the second WPAN channel being at least partly comprised within the WLAN channel bandwidth; and,
instruct the WNN, based on a given mitigation strategy, while being in the mitigation mode, to continuously transmit a jamming signal in the second WPAN channel during a predetermined time period, at a given output power level sufficiently high so that the CCA function on the WLAN does not temporarily cause the WLAN to transmit on the WLAN channel.
10. The method of claim 9 , wherein the mitigation strategy is at least one of:
one or more WNN are instructed to transmit concurrently on the same second WPAN channel; and,
one WNN is instructed to transmit on one second WPAN channel.
11. The method of claim 10 , wherein the second WPAN channel is adjacent to the first WPAN channel.
12. The method of claim 9 when the processor of WNN operates alternatively in the normal mode and the mitigation mode, wherein:
before the processor of a first WNN switches to the mitigation mode, the method further comprises operating the processor of the first WNN to instruct at least one processor of a second WNN to receive data directed to the first WNN; and,
during the predetermined time period wherein the first WNN is in the mitigation mode, the method further comprises operating the processor of the second WNN to store in a memory received data originally directed to the first WNN.
13. The method of claim 9 when the processor of WNN operates alternatively in the normal mode and the mitigation mode, wherein:
before the processor of a first WNN switches to the mitigation mode, the method further comprises operating the processor of the first WNN to request the WNNM to instruct at least one processor of second WNN to receive data directed to the first WNN; and,
during the predetermined time period wherein the first WNN is in the mitigation mode, the method further comprises operating the processor of the second WNN to store in a memory received data originally directed to the first WNN.
14. The method of claim 9 wherein the method further comprises operating the WNNM to increase or shorten the predetermined time period.
15. A non-transitory computer readable medium having stored thereon instructions for causing one or more processing units to execute the method according to claim 9 .