Frequency Channel Selection by an LTE-U Wireless Access Point Operating in the Presence of Other LTE-U and Wi-Fi Access Points

• US 20160088631A1
• Filed: 09/24/2014
• Published: 03/24/2016
• Est. Priority Date: 09/24/2014
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Hedayat, Ahmadreza, Pazhyannur, Rajesh
• Granted Patent: US 9,686,688 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 7/063 Parameters other than those covered in groups H04B7/0623 - H04B7/0634, e.g. channel matrix rank or transmit mode selection
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 36/0077 of access information of target access point
• CPC Class Codes: H04W 48/00 Access restriction access security to prevent unauthorised access H04W12/08; Network selection; Access point selection
• CPC Class Codes: H04W 84/12 WLAN [Wireless Local Area Networks]

Abstract

A Long-Term Evolution-Unlicensed (LTE-U) access point (AP) is configured to operate wirelessly on any of multiple RF channels in an unlicensed frequency band. The AP detects other LTE-U APs and Wi-Fi APs operating on active ones of the multiple channels. The AP determines AP channel statistics for each detected AP. The AP determines, for each active channel, a per-channel metric based on the AP channel statistics. The AP ranks the active channels according to the corresponding per-channel metrics, and selects a best channel on which to transmit in the unlicensed frequency band from among the ranked active channels based on the rankings.

Claims

1. A method comprising:

at a first protocol access point (AP) configured to operate wirelessly according to a first wireless protocol on any of multiple radio frequency (RF) channels in a frequency band associated with the first wireless protocol;

detecting on active ones of the multiple channels first wireless protocol APs operating according to the first wireless protocol and second wireless protocol APs operating according to a second wireless protocol;

determining AP channel statistics related to the detected APs, including a respective received signal strength indication (RSSI) for each detected AP and a respective time utilization indicative of a transmission time of each detected AP operating on the corresponding active channel;

for each active channel, determining a per-channel metric based on the RSSIs and time utilizations for the detected APs operating on that active channel;

ranking the active channels according to the corresponding per-channel metrics; and

selecting a best channel on which to transmit in the frequency band from among the ranked active channels based on the ranking of the active channels.

2. The method of claim 1, wherein:

the second wireless protocol permits a concurrent use of a primary channel and an associated secondary channel by a given second wireless protocol AP operating in a wideband mode;

the determining detected AP channel statistics further includes determining for each detected second wireless protocol AP which of the active channels on which the detected second wireless protocol AP is operating is a primary channel, if any; and

the selecting includes selecting the best channel based on the ranking of the active channels and which ones of the active channels are primary channels.

3. The method of claim 2, wherein:

the first wireless protocol is a Long-Term Evolution-Unlicensed (LTE-U) protocol and each first wireless protocol AP is an LTE-U AP that operates according to the LTE-U protocol in an unlicensed frequency band associated with the LTE-U protocol; and

the second wireless protocol is a Wi-Fi protocol and each second wireless protocol AP is a Wi-Fi AP that operates in accordance with the Wi-Fi protocol.

4. The method of claim 2, wherein the selecting further includes:

searching for a highest ranked one of the active channels among at least three of the highest ranked active channels that is not a first wireless protocol primary channel; and

if the searching finds a highest ranked active channel among the highest ranked active channels that is not a first wireless protocol primary channel, selecting the found highest ranked active channel as the best channel.

5. The method of claim 4, wherein the selecting further includes:

if the searching does not find a highest ranked active channel among the highest ranked active channels that is not a first wireless protocol primary channel, selecting the highest ranked active channel as the best channel.

6. The method of claim 2, wherein the selecting further includes:

searching for a highest ranked one of the active channels among at least three of the highest ranked active channels that meets either (i) a first condition that the active channel is not a first wireless protocol primary channel, or (ii) a second condition that the active channel is a first wireless protocol primary channel and has a corresponding total interference power representing a sum of the RSSIs of all of the APs operating on the active channel that is less than a predetermined interference threshold; and

if the searching finds a highest ranked active channel among the highest ranked active channels that meets either the first condition or the second condition, selecting the found highest ranked active channel as the best channel.

7. The method of claim 6, wherein the selecting further includes:

if the searching does not find a highest ranked active channel among the highest ranked active channels that meets either the first condition or the second condition, determining a second per-channel metric for each of the at least three of the highest ranked active channels based on RSSIs and time utilizations for each of the channels; and

selecting one of the at least three of the highest ranked active channels as the best channel based on the second per-channel metric.

8. The method of claim 2, wherein the determining detected AP channel statistics further includes:

determining a channel bandwidth of each active channel being used by the corresponding AP operating on that active channel; and

if the channel bandwidths include different channel bandwidths, normalizing the respective RSSIs based on a smallest channel bandwidth among the different channel bandwidths,

wherein the determining the per-channel metric includes determining the per-channel metric based on the normalized RSSIs.

9. The method of claim 1, wherein the determining a per-channel metric includes, for each active channel:

determining a total RSSI of the active channel based on the individual RSSIs of all of the detected APs operating on the active channel;

determining a total time utilization of the active channel based on the individual time utilizations of all of the detected APs operating on the active channel; and

determining the per-channel metric for the active channel based on the total RSSI and the total time utilization for the active channel.

10. The method of claim 9, wherein the determining a per-channel metric includes determining a per-channel metric C_i for each active channel designated as an i'"'"'th active channel, according to the equation:

C_—

i=(1−

SumU)*log 2(1+1/(AWGN+SumIntf)),

where;

AWGN is an Average White Gaussian Noise level determined for the i'"'"'th active channel;

SumU is a total channel time utilization represented as a sum of the time utilizations of all of the detected APs operating in the i'"'"'th active channel; and

SumIntf is a total channel interference represented as a sum of the RSSIs of all of the detected APs operating in the i'"'"'th active channel.

11. The method of claim 1, wherein the determining a per-channel metric includes, for each active channel:

calculating for each detected AP operating in the active channel a product of a first function that is based on the RSSI for that detected AP and a second function that is based on the time utilization for that detected AP; and

averaging the calculated products corresponding to the detected APs in the active channel across a total number of detected APs in the active channel, to produce the per-channel metric for the active channel.

12. The method of claim 11, wherein the determining a per-channel metric includes determining a per-channel metric C_i for each active channel designated as an i'"'"'th active channel, according to the equation:

C_—

i=average{(1−

U_—

j)*log 2(1+1/(AWGN+IntF_—

j)},

where;

AWGN is an Average White Gaussian Noise level determined for the i'"'"'th active channel; and

U_j and IntF_j are respective values for the time utilization and the RSSI for a j'"'"'th detected WiFi/LTE-U AP operating in the i'"'"'th active channel.

13. The method of claim 1, wherein the frequency band associated with the first wireless protocol is an unlicensed frequency band associated with the first wireless protocol.

14. The method of claim 1, wherein, if N APs are detected in an active channel designated as the i'"'"'th active channel, the determining a per-channel metric includes the determining a per-channel metric C_i for the i'"'"'th active channel according to the equation:

C_—

i=f(U_—

1, . . . ,U_—

N,R_—

1, . . . ,R_—

N),

where;

f denotes “

a function of”

;

U_n (n goes from 1, . . . , N) corresponds to the utilization of detected AP n; and

R_n is the RSSI of the respective detected AP.

15. An apparatus comprising:

a radio subsystem to operate wirelessly according to a first wireless protocol on any of multiple radio frequency (RF) channels in a frequency band associated with the first wireless protocol, and to receive wireless transmissions formatted according to a second wireless protocol; and

a processor coupled to the radio subsystem, to;

detect on active ones of the multiple channels first wireless protocol APs operating according to the first wireless protocol and second wireless protocol APs operating according to the second wireless protocol;

determine AP channel statistics related to the detected APs, including a respective received signal strength indication (RSSI) for each detected AP and a respective time utilization indicative of a transmission time of each detected AP operating on the corresponding active channel;

for each active channel, determine a per-channel metric based on the RSSIs and time utilizations for the detected APs operating on that active channel;

rank the active channels according to the corresponding per-channel metrics; and

select a best channel on which to transmit in the frequency band from among the ranked active channels based on the ranking of the active channels.

16. The apparatus of claim 15, wherein:

the second wireless protocol permits a concurrent use of a primary channel and an associated secondary channel by a given second wireless protocol AP operating in a wideband mode;

the processor is configured to determine by determining for each detected second wireless protocol AP which of the active channels on which the detected second wireless protocol AP is operating is a primary channel, if any; and

the processor is configured to select by selecting the best channel based on the ranking of the active channels and which ones of the active channels are primary channels.

17. The apparatus of claim 16, wherein:

the first wireless protocol is a Long-Term Evolution-Unlicensed (LTE-U) protocol and each first wireless protocol AP is an LTE-U AP that operates according to the LTE-U protocol in an unlicensed frequency band associated with the LTE-U protocol; and

the second wireless protocol is a Wi-Fi protocol and each second wireless protocol AP is a Wi-Fi AP that operates in accordance with the Wi-Fi protocol.

18. The apparatus of claim 16, wherein the processor is configured to select by:

searching for a highest ranked one of the active channels among at least three of the highest ranked active channels that is not a first wireless protocol primary channel; and

if the searching finds a highest ranked active channel among the highest ranked active channels that is not a first wireless protocol primary channel, selecting the found highest ranked active channel as the best channel.

19. The apparatus of claim 18, wherein the processor is further configured to select by:

if the searching does not find a highest ranked active channel among the highest ranked active channels that is not a first wireless protocol primary channel, selecting the highest ranked active channel as the best channel.

20. The apparatus of claim 16, wherein the processor is further configured to select by:

searching for a highest ranked one of the active channels among at least three of the highest ranked active channels that meets either (i) a first condition that the active channel is not a first wireless protocol primary channel, or (ii) a second condition that the active channel is a first wireless protocol primary channel and has a corresponding total interference power representing a sum of the RSSIs of all of the APs operating on the active channel that is less than a predetermined interference threshold; and

if the searching finds a highest ranked active channel among the highest ranked active channels that meets either the first condition or the second condition, selecting the found highest ranked active channel as the best channel.

21. The apparatus of claim 20, wherein the processor is further configured to select by:

if the searching does not find a highest ranked active channel among the highest ranked active channels that meets either the first condition or the second condition, determining a second per-channel metric for each of the at least three of the highest ranked active channels based on RSSIs and time utilizations for each of the channels; and

selecting one of the at least three of the highest ranked active channels as the best channel based on the second per-channel metric.

22. The apparatus of claim 16, wherein the processor is further configured to determine detected AP channel statistics by:

determining a channel bandwidth of each active channel being used by the corresponding AP operating on that active channel; and

if the channel bandwidths include different channel bandwidths, normalizing the respective RSSIs based on a smallest channel bandwidth among the different channel bandwidths,

wherein the determining the per-channel metric includes determining the per-channel metric based on the normalized RSSIs.

23. The apparatus of claim 15, wherein the processor is configured to determine a per-channel metric by, for each active channel:

determining a total RSSI of the active channel based on the individual RSSIs of all of the detected APs operating on the active channel;

determining a total time utilization of the active channel based on the individual time utilizations of all of the detected APs operating on the active channel; and

determining the per-channel metric for the active channel based on the total RSSI and the total time utilization for the active channel.

24. The apparatus of claim 15, wherein the frequency band associated with the first wireless protocol is an unlicensed frequency band associated with the first wireless protocol.

25. A tangible computer readable storage media encoded with instructions that, when executed by a processor of an access point (AP) configured to operate wirelessly according to a first wireless protocol on any of multiple radio frequency (RF) channels in a frequency band associated with the first wireless protocol, cause the processor to:

detect on active ones of the multiple channels first wireless protocol APs operating according to the first wireless protocol and second wireless protocol APs operating according to a second wireless protocol;

determine AP channel statistics related to the detected APs, including a respective received signal strength indication (RSSI) for each detected AP and a respective time utilization indicative of a transmission time of each detected AP operating on the corresponding active channel;

for each active channel, determine a per-channel metric based on the RSSIs and time utilizations for the detected APs operating on that active channel;

rank the active channels according to the corresponding per-channel metrics; and

select a best channel on which to transmit in the frequency band from among the ranked active channels based on the ranking of the active channels.

26. The computer readable storage media of claim 25, wherein:

the second wireless protocol permits a concurrent use of a primary channel and an associated secondary channel by a given second wireless protocol AP operating in a wideband mode;

the instructions include instructions to cause the processor to determine for each detected second wireless protocol AP which of the active channels on which the detected second wireless protocol AP is operating is a primary channel, if any; and

the instructions include instructions to cause the processor to select the best channel based on the ranking of the active channels and which ones of the active channels are primary channels.

27. The computer readable storage media of claim 26, wherein:

the first wireless protocol is a Long-Term Evolution-Unlicensed (LTE-U) protocol and each first wireless protocol AP is an LTE-U AP that operates according to the LTE-U protocol in an unlicensed frequency band associated with the LTE-U protocol; and

the second wireless protocol is a Wi-Fi protocol and each second wireless protocol AP is a Wi-Fi AP that operates in accordance with the Wi-Fi protocol.

28. The computer readable storage media of claim 26, further including instructions to cause the processor to:

search for a highest ranked one of the active channels among at least three of the highest ranked active channels that is not a first wireless protocol primary channel; and

if the search finds a highest ranked active channel among the highest ranked active channels that is not a first wireless protocol primary channel, select the found highest ranked active channel as the best channel.

29. The computer readable storage media of claim 26, further including instructions to cause the processor to:

search for a highest ranked one of the active channels among at least three of the highest ranked active channels that meets either (i) a first condition that the active channel is not a first wireless protocol primary channel, or (ii) a second condition that the active channel is a first wireless protocol primary channel and has a corresponding total interference power representing a sum of the RSSIs of all of the APs operating on the active channel that is less than a predetermined interference threshold; and

if the search finds a highest ranked active channel among the highest ranked active channels that meets either the first condition or the second condition, select the found highest ranked active channel as the best channel.

30. The computer readable storage media of claim 25, further including instructions to cause the processor to determine a per-channel metric by, for each active channel:

determining a total RSSI of the active channel based on the individual RSSIs of all of the detected APs operating on the active channel;

determining a total time utilization of the active channel based on the individual time utilizations of all of the detected APs operating on the active channel; and

determining the per-channel metric for the active channel based on the total RSSI and the total time utilization for the active channel.