Method for sending channel reservation signal and base station

• US 10,735,998 B2
• Filed: 06/22/2018
• Issued: 08/04/2020
• Est. Priority Date: 12/24/2015
• Status: Active Grant

• Current Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Huawei Technologies Co., Ltd. (Huawei Investment & Holding Co., Ltd.)
• Inventors: Li, Hantao, Li, Zhenyu, Han, Jinxia, Ma, Sha
• Primary Examiner(s): Ngo, Ricky Q
• Assistant Examiner(s): Steiner, Stephen N
• Application Number:
  US16/016,339
• Publication Number:
  US 20180343589A1
• Time in Patent Office: 774 Days
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 28/26 Resource reservation
• CPC Class Codes: H04W 74/08 Non-scheduled access, e.g. ALOHA hybrid access H04W74/02
• CPC Class Codes: H04W 74/0825 with collision detection

Abstract

A method for sending a channel reservation signal and a base station, related to the field of communications technologies, includes: detecting, by a base station, whether a system signal is received on an unlicensed channel; and sending, by the base station, a channel reservation signal on the unlicensed channel to reserve the unlicensed channel based on the base station detecting that the system signal is received on the unlicensed channel.

Claims

1. A method for sending a channel reservation signal, the method comprising:

detecting, by a base station, whether a system signal is received at the base station on an unlicensed channel, wherein the system signal is a wireless fidelity (WiFi) signal in a WiFi system;

performing, by the base station, clear channel assessment (CCA) based on detecting that the system signal is received on the unlicensed channel,

wherein the CCA is started by the base station in a cell on/off mechanism,

wherein the CCA is started in N subframes prior to a moment at which a licensed-assisted access (LAA) system, to which the base station belongs, enters a cell-on state, and

wherein a duration of the N subframes is a transmit opportunity (TXOP) in the WiFi system; and

sending, by the base station, a channel reservation signal on the unlicensed channel to reserve the unlicensed channel based on the CCA indicating that the unlicensed channel is idle.

2. The method according to claim 1, wherein detecting, by the base station, whether the system signal is received at the base station on the unlicensed channel comprises:

detecting, by the base station in each of one or more detection periods, whether the system signal is received at the base station on the unlicensed channel, wherein each detection period comprises one or more detection durations; and

performing, by the base station, the CCA further comprises;

stopping, by the base station, detection of the system signal in one of the detection periods based on detecting, in one of the detection durations, that the base station receives the system signal on the unlicensed channel, and performing the CCA.

3. The method according to claim 1, wherein the CCA meets at least one of the following conditions:

a value of a detection threshold for the CCA is less than or equal to d,

wherein d represents a smaller value between a detection threshold used by the base station to perform CCA for an intra-system and a detection threshold used by the base station to perform CCA for an inter-system;

a detection duration of the CCA is greater than or equal to a larger value between a detection duration of CCA performed by the base station for an intra-system and a detection duration of CCA performed by the base station for an inter-system;

or

a defer duration of the CCA is greater than or equal to a larger value between a defer duration of CCA performed by the base station for an intra-system and a defer duration of CCA performed by the base station for an inter-system.

4. The method according to claim 1, wherein sending, by the base station, the channel reservation signal on the unlicensed channel comprises:

successively sending, by the base station, S channel reservation signals on the unlicensed channel,

wherein a duration of a reservation field of an s^th channel reservation signal is (S−

s)*T₀+T, wherein 1≤

s≤

S, both S and s are integers, S is a total number of channel reservation signals, T₀ is a duration occupied by the s^th channel reservation signal, and T is a to-be-reserved duration for data transmission on the unlicensed channel.

5. The method according to claim 1, wherein sending, by the base station, the channel reservation signal on the unlicensed channel comprises:

sending, by the base station, the channel reservation signal on each target orthogonal frequency division multiplexing (OFDM) symbol on the unlicensed channel,

wherein the target OFDM symbols are P OFDM symbols starting from a first OFDM symbol following an OFDM symbol of a target moment,

wherein the target moment is a moment at which the base station determines that the unlicensed channel is idle, and

wherein P is an integer greater than or equal to 1.

6. The method according to claim 5, wherein P is greater than 1, and wherein:

a reservation field of the channel reservation signal sent on a p^th target OFDM symbol indicates a duration left after the p^th target OFDM symbol is occupied by the channel reservation signal, and a reservation field of the channel reservation signal sent on a P^th target OFDM symbol indicates a sum of a to-be-reserved duration,

wherein a duration left after the P^th target OFDM symbol is occupied by the channel reservation signal, and wherein 1≤

p<

P, and p is an integer;

a reservation field of the channel reservation signal sent on each target OFDM symbol indicates a sum of a to-be-reserved duration and a duration left after the target OFDM symbol is occupied by the channel reservation signal;

or

a reservation field of the channel reservation signal sent on an m^th target OFDM symbol indicates a sum of a to-be-reserved duration and (P−

m)*OFDM symbol durations, wherein 1≤

m≤

P, and m is an integer.

7. The method according to claim 5, wherein padding information is further sent in a duration left after each of the target OFDM symbols is occupied by the channel reservation signal, and the padding information comprises any one piece of the following information:

a WiFi control frame;

a combination of a WiFi signal preamble and a signal field;

or

a combination of a WiFi signal preamble, a signal field, and invalid data.

8. The method according to claim 7, wherein:

sending the padding information in each of the target OFDM symbols after (i) the channel reservation signal in each of the target OFDM symbols, and (ii) a length field in the signal field is marked as 0 in response to the padding information in each of the target OFDM symbols comprising either of the following;

(i) the combination of the WiFi signal preamble and the signal field, or

(ii) the combination of the WiFi signal preamble, the signal field, and the invalid data;

or

sending the padding information in each of the target OFDM symbols before (i) the channel reservation signal in each of the target OFDM symbols, and (ii) the length field in the signal field is marked as 0 or a duration left after each of the target OFDM symbols is occupied by the signal preamble and the signal field in response to the padding information in the target OFDM symbol comprising either of the following information;

(i) the combination of the WiFi signal preamble and the signal field, or

(ii) the combination of the WiFi signal preamble, the signal field, and the invalid data.

9. The method according to claim 1, wherein sending, by the base station, the channel reservation signal on the unlicensed channel comprises:

sending, by the base station, a first channel reservation signal on the unlicensed channel; and

sending a second channel reservation signal after a preset time segment expires,

wherein a modulation order of data transmitted in a subframe of the second channel reservation signal is less than or equal to a modulation order of data transmitted in a subframe reserved by the first channel reservation signal, and a code rate of the data transmitted in the subframe of the second channel reservation signal is less than or equal to a code rate of the data transmitted in the subframe reserved by the first channel reservation signal.

10. The method according to claim 1, wherein before sending, by the base station, the channel reservation signal on the unlicensed channel, the method further comprises:

performing, by the base station, sample-rate conversion on the channel reservation signal, wherein a sampling rate of the sample-rate conversion is a sampling rate of an a licensed-assisted access (LAA) signal.

11. The method according to claim 1, wherein sending, by the base station, the channel reservation signal on the unlicensed channel comprises:

sending, by the base station in the cell on/off mechanism, the channel reservation signal on the unlicensed channel on one or more orthogonal frequency division multiplexing (OFDM) symbols prior to a moment at which the LAA system to which the base station belongs enters a cell on state;

or

sending, by the base station in the cell on/off mechanism, the channel reservation signal on the unlicensed channel on one or more OFDM symbols following the moment at which the LAA system to which the base station belongs enters the cell on state;

or

sending, by the base station in the cell on/off mechanism, the channel reservation signal on the unlicensed channel on one or more OFDM symbols in a data region following the moment at which the LAA system to which the base station belongs enters the cell on state.

12. The method according to claim 1, wherein sending, by the base station, the channel reservation signal on the unlicensed channel to reserve the unlicensed channel comprises:

based on the CCA indicating that the unlicensed channel is idle and T1≥

T2, after the CCA ends, sending, by the base station, the channel reservation signal on the unlicensed channel by deferring a T1-T2 duration, to reserve the unlicensed channel;

or

based on the CCA indicating that the unlicensed channel is idle and T1<

T2, sending, by the base station, the channel reservation signal on the unlicensed channel to reserve the unlicensed channel,

wherein T1 is a delay of switching, by the licensed-assisted access LAA system to which the base station belongs, from uplink transmission to downlink transmission, and

wherein T2 is a time required by the base station to send the channel reservation signal to a transmitter.

13. An apparatus comprising:

a processor and a non-transitory computer-readable storage medium coupled to the processor and storing programming instructions for execution by the processor, the programming instructions, when executed by the processor, facilitate performing;

detecting whether a system signal on an unlicensed channel is received, wherein the system signal is a wireless fidelity (WiFi) signal in a WiFi system;

performing clear channel assessment (CCA) based on detecting that the system signal is received on the unlicensed channel,

wherein the CCA is started in a cell on/off mechanism,

wherein the CCA is started in N subframes prior to a moment at which a licensed-assisted access (LAA) system enters a cell-on state, and

wherein a duration of the N subframes is a transmit opportunity (TXOP) in the WiFi system; and

sending a channel reservation signal on the unlicensed channel to reserve the unlicensed channel based on the CCA indicating that the unlicensed channel is idle.

14. The apparatus according to claim 13, wherein the processor further facilitates performing:

detecting, in each of one or more detection periods, whether the system signal on the unlicensed channel is received, wherein each detection period comprises one or more detection durations; and

based on detecting, in a detection duration, that the base station receives the system signal on the unlicensed channel, stopping detection of the system signal in the detection period to which the detection duration belongs, and performing CCA.

15. The apparatus according to claim 13, wherein the CCA meets at least one of the following conditions:

a value of a detection threshold for the CCA is less than or equal to d,

wherein d represents a smaller value between a detection threshold used by the apparatus to perform CCA for an intra-system and a detection threshold used by the apparatus to perform CCA for an inter-system;

or

a detection duration of the CCA is greater than or equal to a larger value between a detection duration of CCA performed by the apparatus for an intra-system and a detection duration of CCA performed by the apparatus for an inter-system;

or

a defer duration of the CCA is greater than or equal to a larger value between a defer duration of CCA performed by the apparatus for an intra-system and a defer duration of CCA performed by the apparatus for an inter-system.

16. The apparatus according to claim 13, wherein the processor further facilitates performing:

successively sending S channel reservation signals on the unlicensed channel, wherein a reservation field of an s^th channel reservation signal is (S−

s)*T₀+T, wherein 1≤

s≤

S, both S and s are integers, To is a duration occupied by a channel reservation signal, and T is a to-be-reserved duration which is a duration for data transmission on the unlicensed channel.

17. The apparatus according to claim 13, wherein the processor further facilitates performing:

sending the channel reservation signal on each target orthogonal frequency division multiplexing (OFDM) symbol on the unlicensed channel,

wherein the target OFDM symbols are P OFDM symbols starting from a first OFDM symbol following an OFDM symbol of a target moment,

wherein the target moment is a moment at which the apparatus determines that the unlicensed channel is idle, and

wherein P is an integer greater than or equal to 1.

18. The apparatus according to claim 17, wherein P is greater than 1, and wherein:

a reservation field of the channel reservation signal sent on a p^th target OFDM symbol indicates a duration left after the p^th target OFDM symbol is occupied by the channel reservation signal, and a reservation field of the channel reservation signal sent on a P^th target OFDM symbol indicates a sum of a to-be-reserved duration, wherein a duration left after the P^th target OFDM symbol is occupied by the channel reservation signal, and wherein 1≤

p<

P, and p is an integer;

a reservation field of the channel reservation signal sent on each target OFDM symbol indicates a sum of a to-be-reserved duration and a duration left after the target OFDM symbol is occupied by the channel reservation signal;

or

a reservation field of the channel reservation signal sent on an m^th target OFDM symbol indicates a sum of a to-be-reserved duration and (P−

m)*OFDM symbol durations, wherein 1≤

m≤

P, and m is an integer.

19. The apparatus according to claim 17, wherein padding information is further sent in a duration left after each of the target OFDM symbols is occupied by the channel reservation signal, and the padding information comprises any one piece of the following information:

a WiFi control frame;

a combination of a WiFi signal preamble and a signal field;

or

a combination of a WiFi signal preamble, a signal field, and invalid data.

20. The apparatus according to claim 19, wherein:

sending the padding information in each of the target OFDM symbols after (i) the channel reservation signal in each of the target OFDM symbols, and (ii) a length field in the signal field is marked as 0 in response to the padding information in each of the target OFDM symbols comprising either of the following;

(i) the combination of the WiFi signal preamble and the signal field, or

(ii) the combination of the WiFi signal preamble, the signal field, and the invalid data;

or

sending the padding information in each of the target OFDM symbols before (i) the channel reservation signal in each of the OFDM symbols, and (ii) a length field in the signal field is marked as 0 or a duration left after each of the target OFDM symbols is occupied by the signal preamble and the signal field in response to the padding information in each of the target OFDM symbols comprising either of the following information;

(i) the combination of the WiFi signal preamble and the signal field, or

(ii) the combination of the WiFi signal preamble, the signal field, and the invalid data.

21. The apparatus according to claim 13, wherein the processor further facilitates performing:

sample-rate conversion on the channel reservation signal to obtain a target signal, wherein a sampling rate of the target signal is a sampling rate of a licensed-assisted access (LAA) signal; and

sending the target signal on the unlicensed channel.

22. The apparatus according to claim 13, wherein the processor further facilitates performing:

sending a request to send (RTS) frame to a target terminal, wherein a receiver media access control (MAC) address field of the RTS frame is used to mark a MAC address of a WiFi chip of the target terminal.

23. The apparatus according to claim 13, wherein the processor further facilitates performing:

sending the channel reservation signal on the unlicensed channel on one or more orthogonal frequency division multiplexing (OFDM) symbols prior to a moment at which a the LAA system to which the base station belongs enters a cell on state;

or

sending the channel reservation signal on the unlicensed channel on one or more OFDM symbols following the moment at which the LAA system to which the apparatus belongs enters the cell on state;

or

sending the channel reservation signal on the unlicensed channel on one or more OFDM symbols in a data region following the moment at which the LAA system to which the apparatus belongs enters the cell on state.

24. The apparatus according to claim 13, wherein the processor further facilitates performing:

based on the CCA indicating that the unlicensed channel is idle and T1≥

T2, after the CCA ends, send the channel reservation signal on the unlicensed channel by deferring a T1-T2 duration, to reserve the unlicensed channel;

or

based on the CCA indicating that the unlicensed channel is idle and T1<

T2, send the channel reservation signal on the unlicensed channel to reserve the unlicensed channel,

wherein T1 is a delay of switching, by the licensed-assisted access (LAA) system to which the base station belongs, from uplink transmission to downlink transmission, and

wherein T2 is a time required by the base station to send the channel reservation signal to a transmitter.