Data transmission method and device
Disclosed is a data transmission method. The method comprises: reserving a first channel and a second channel, where the first channel is used for transmitting data and the second channel is used for transmitting ACKs; sending data to a receiving end on the first channel that is reserved; receiving an ACK that is sent by the receiving end and corresponds to the data on the second channel that is reserved and determining whether the data needs to be cached based on information carried in the ACK; and if the information carried in the ACK indicates that the receiving end has correctly received the data, clearing the data that is cached by a sending end. Through separate transmission of the data and the ACK, an efficiency problem of the sending end in providing MAC in a wireless system in a condition of a limited cache capacity is resolved.
1. A method for transmitting data comprising:
reserving, by a transmitter, a first channel and a second channel, wherein the first channel is for communicating the data and the second channel is for communicating an acknowledgement (ACK) corresponding to the data, wherein reserving the first and second channels comprises:
sending, by the transmitter, on the first channel, a first channel reservation frame to the receiver, and sending, by the transmitter, on the second channel, a second channel reservation frame to the receiver, wherein the first channel reservation frame is used to reserve the first channel and carry information regarding a time for reserving the first channel, and the second channel reservation frame is used to reserve the second channel and carry information regarding a time for reserving the second channel; and
determining, by the transmitter, whether the first channel is successfully reserved, based on at least one of a response frame of the first channel reservation frame and a response frame of the second channel reservation frame from the receiver, and determining, by the transmitter, whether the second channel is successfully reserved, based on at least one of the response frame of the first channel reservation frame and the response frame of the second channel reservation frame from the receiver;
in response to the first channel and the second channel being successfully reserved, sending, on the reserved first channel, the data to a receiver and receiving, on the reserved second channel, the ACK corresponding to the data from the receiver;
the method further including:
a) calculating, by the receiver, a time for reaching a maximum cache capacity of the transmitter based on a rate at which the transmitter sends the data, the rate being carried by the preamble, or
b) receiving, by the receiver, information regarding the time for reaching the maximum cache capacity of the transmitter from the transmitter; and
the method further including:
a) sending, by the receiver, the ACK to the transmitter in a limited contention-free manner or via carrier sense multiple access (CSMA), or
b) before the time for reaching the maximum cache capacity of the transmitter, (i) sending, by the receiver, the ACK to the transmitter in response to an idle PCF inter-frame space (PIFS) time of the second channel elapsing, a short inter-frame space (SIFS) time of the preamble elapsing, or (ii) a response request frame corresponding to the data being sent by the transmitter,
wherein the maximum cache capacity is carried in at least one of (a) the first and second channel reservation frames, (b) a preamble or (c) a capability field, wherein the maximum cache capacity is used by the receiver to determine a latest time for sending the ACK corresponding to the data to the transmitter.
2. The method according to claim 1 , wherein sending, on the reserved first channel, the data to the receiver comprises: sending, by the transmitter, on the reserved first channel, the data to a plurality of receivers via downlink multi-user transmission;
wherein the method further comprises sending, by the transmitter, on the reserved second channel, response request frames corresponding to the data to the plurality of receivers;
wherein:
a) in case the plurality of receivers support uplink multi-user transmission, the plurality of receivers, in response to receiving the response request frames, send acknowledgements (ACKs) to the transmitter at a same time via uplink multi-user transmission before a minimum time for reaching maximum cache capacities of the transmitter; or
b) in case the plurality of receivers do not all support the uplink multi-user transmission, the plurality of receivers, in response to receiving the response request frames, calculate the times for reaching the maximum cache capacities of the transmitter, based on rates carried by the preamble at which the transmitter sends respectively the data to the plurality of receivers, and the plurality of receivers send respectively the ACKs to the transmitter before the times for reaching the maximum cache capacities of the transmitter; or
c) the plurality of receivers send on the second channel the ACKs to the transmitter in a limited contention-free manner; and
wherein receiving, on the reserved second channel, the ACK corresponding to the data comprises receiving, by the transmitter, on the second channel, the ACKs corresponding to the data from the plurality of receivers.
3. The method according to claim 1 , wherein sending, on the reserved first channel, the data to the receiver comprises: sending, by a plurality of transmitters, on the first channel, the data to the receiver via uplink multi-user transmission, and
wherein the method further comprises:
a) calculating, by the receiver, latest times for reaching maximum cache capacities of the plurality of transmitters based on rates carried by preambles at which the plurality of transmitters send the data to the receiver, so that before a minimum time for reaching the maximum cache capacities of the plurality of transmitters, the receiver sends acknowledgements (ACKs) to the plurality of transmitters at a same time via downlink multi-user transmission; or
b) sending, by the plurality of transmitters, information regarding latest times to the receiver, so that before the minimum time for reaching the maximum cache capacities of the plurality of transmitters, the receiver sends the ACKs to the plurality of transmitters at a same time via downlink multi-user transmission; or
c) calculating, by the receiver, the times for reaching the maximum cache capacities of the plurality of transmitters based on the rates carried by the preambles at which the plurality of transmitters send the data to the receiver, so that before the times for reaching the maximum cache capacities of the plurality of transmitters, the receiver sends the ACKs to the plurality of transmitters; or
d) sending, by the receiver, on the second channel, the ACKs to the plurality of transmitters in a limited contention-free manner or via carrier sense multiple access (CSMA); and
wherein receiving, on the reserved second channel, the ACK corresponding to the data from the receiver comprises: receiving, by the plurality of transmitters, on the second channel, the ACKs corresponding to the data from the receiver.
4. The method according to claim 1 , wherein sending, on the reserved first channel, the data to the receiver comprises: sending, by a plurality of transmitters, on the first channel, the data to a plurality of receivers, via cooperative transmission;
wherein the method further comprises:
a) sending, by the plurality of transmitters, on the reserved second channel, response request frames corresponding to the data, via a poll (Poll), so that the plurality of receivers receive the response request frames and after a short inter-frame space (SIFS), sends ACKs to the plurality of transmitters; or
b) requesting, by the plurality of transmitters, the plurality of receivers to send the ACKs, on the second channel in a limited contention-free manner; or
c) sending, by the plurality of receivers, the ACKs to the plurality of transmitters in a limited contention-free manner; and
wherein receiving, on the reserved second channel, the ACK corresponding to the data from the receiver comprises receiving, by the plurality of transmitters, on the second channel, the ACKs corresponding to the data from the plurality of receivers.
5. The method according to claim 1 , wherein a starting time for channel reservation is carried in at least one of the first channel reservation frame and the second channel reservation frame, in the data or in the preamble.
6. The method according to claim 1 , further comprising:
sending, by the transmitter, an instruction for returning to a preset operating mode to the receiver in case at least one of the first channel and the second channel is not successfully reserved by the transmitter.
7. A method for transmitting data comprising:
reserving, by a receiver, a first channel and a second channel, wherein the first channel is for communicating the data and the second channel is for communicating an acknowledgement (ACK) corresponding to the data wherein reserving the first and second channels comprises:
receiving, by the receiver, on the first channel, a first channel reservation frame from the transmitter, and receiving, by the receiver, on the second channel, a second channel reservation frame from the transmitter, wherein the first channel reservation frame is used to reserve the first channel and carry information regarding a time for reserving the first channel, and the second channel reservation frame is used to reserve the second channel and carry information regarding a time for reserving the second channel; and
sending, by the receiver, at least one of a response frame of the first channel reservation frame and a response frame of the second channel reservation frame, to the transmitter for enabling the transmitter to determine whether the first channel is successfully reserved based on the at least one of the response frame of the first channel reservation frame and the response frame of the second channel reservation frame from the receiver, and for enabling the transmitter to determine whether the second channel is successfully reserved based on the at least one of the response frame of the first channel reservation frame and the response frame of the second channel reservation frame from the receiver;
in response to the first channel and the second channel being successfully reserved, receiving the data from a transmitter on the reserved first channel and sending, on the reserved second channel, the ACK corresponding to the data to the transmitter;
the method further including:
a) calculating, by the receiver, a time for reaching a maximum cache capacity of the transmitter, based on a rate at which the transmitter sends the data, the rate being carried by the preamble, or
b) receiving, by the receiver, information regarding the time for reaching the maximum cache capacity of the transmitter from the transmitter; and
the method further including:
a) sending, by the receiver, the ACK to the transmitter in a limited contention-free manner or via carrier sense multiple access (CSMA), or
b) before the time for reaching the maximum cache capacity of the transmitter, sending, by the receiver, the ACK to the transmitter in response to an idle PCF inter-frame space (PIFS) time of the second channel elapsing, (i) a short inter-frame space (SIFS) time of the preamble elapsing, or (ii) a response request frame corresponding to the data being sent by the transmitter,
wherein the maximum cache capacity is carried in at least one of (a) the first and second channel reservation frames, (b) a preamble or (c) a capability field, wherein the maximum cache capacity is used by the receiver to determine a latest time for sending the ACK corresponding to the data to the transmitter.
8. The method according to claim 7 ,
wherein receiving the data from the transmitter on the first channel comprises sending, by the transmitter, on the reserved first channel, the data to a plurality of receivers via downlink multi-user transmission,
wherein the method further comprises sending, by the transmitter, on the reserved second channel, response request frames corresponding to the data to the plurality of receivers, and
wherein:
a) in case the plurality of receivers support uplink multi-user transmission, the plurality of receivers, in response to receiving the response request frames, send acknowledgements (ACKs) to the transmitter at a same time via uplink multi-user transmission before a minimum time for reaching maximum cache capacities of the transmitter; or
b) in case the plurality of receivers do not all support the uplink multi-user transmission, the plurality of receivers, in response to receiving the response request frames, calculate the times for reaching the maximum cache capacities of the transmitter, based on rates at which the transmitter sends respectively the data to the plurality of receivers carried by the preamble, and the plurality of receivers send respectively the ACKs to the transmitter before the times for reaching the maximum cache capacities of the transmitter;
or
c) the plurality of receivers send on the second channel, the ACKs to the transmitter in a limited contention-free manner; and
wherein the method further comprises receiving, by the transmitter, on the second channel, the ACKs corresponding to the data from the plurality of receivers.
9. The method according to claim 7 , wherein receiving the data from the transmitter on the first channel comprises sending, by a plurality of transmitters, on the first channel, the data to the receiver via uplink multi-user transmission; and
a) calculating, by the receiver, latest times for reaching maximum cache capacities of the plurality of transmitters based on rates carried by preambles at which the plurality of transmitters send the data to the receiver, so that before a minimum time for reaching the maximum cache capacities of the plurality of transmitters, the receiver sends acknowledgements (ACKs) to the plurality of transmitters at a same time via downlink multi-user transmission; or
b) sending, by the plurality of transmitters, information regarding latest times to the receiver, so that before the minimum time for reaching the maximum cache capacities of the plurality of transmitters, the receiver sends the ACKs to the plurality of transmitters at a same time via downlink multi-user transmission; or
c) calculating, by the receiver, the times for reaching the maximum cache capacities of the plurality of transmitters based on the rates at which the plurality of transmitters send the data to the receiver carried by the preambles, so that before the times for reaching the maximum cache capacities of the plurality of transmitters, the receiver sends the ACKs to the plurality of transmitters;
wherein sending, on the reserved second channel, the ACK corresponding to the data to the transmitter comprises:
sending, by the receiver, on the second channel, the ACKs to the plurality of transmitters in a limited contention-free manner or via carrier sense multiple access (CSMA); and
receiving, by the plurality of transmitters, on the second channel, the ACKs corresponding to the data sent by the receiver.
10. The method according to claim 7 , wherein the method further comprises sending, by a plurality of transmitters, on the first channel, the data to a plurality of receivers via cooperative transmission; and
a) sending, by the plurality of transmitters, on the reserved second channel, response request frames corresponding to the data, via a poll (Poll), so that the plurality of receivers receive the response request frames and after a short inter-frame space (SIFS), and send ACKs to the plurality of transmitters; or
b) requesting, by the plurality of transmitters, the plurality of receivers to send the ACKs, on the second channel in a limited contention-free manner; or
c) sending, by the plurality of receivers, the ACKs to the plurality of transmitters in a limited contention-free manner; and
wherein the method further comprises receiving, by the plurality of transmitters, on the second channel, the ACKs corresponding to the data from the plurality of receivers.
11. The method according to claim 7 , wherein a starting time for channel reservation is carried in at least one of the first channel reservation frame and the second channel reservation frame, in the data or in the preamble.