Method and apparatus for simultaneous multi-user and direct link transmissions with reduced interferences
A triggering frame in a wireless network grants a medium to an AP for a TXOP. The frame defines RUs and allocates Uplink RUs to UL transmissions for an UL duration and Direct Link RUs to P2P transmissions. All the P2P exchanges are nested within the UL duration, hence avoiding an acknowledgment frame in the DiL RUs to interfere with a block-ack frame of the AP after the UL transmissions. This is relevant for DiL RUs adjacent, in frequency, to the other defined RUs. The block-ack frame is duplicated over the DiL RUs. The RU immediately adjacent to the DiL RUs is declared, in the triggering frame, as being unused: no non-AP station is allowed to use it during the UL duration, or even the TXOP. Such empty RU may be declared only in case the DiL transmission requires a response frame from the destination P2P station.
1 . A communication method in a wireless network comprising, at a first peer-to-peer (P2P) station (STA):
receiving, from an access point (AP) a triggering frame reserving a transmission opportunity (TXOP), the triggering frame allocating one direct link (DiL) resource unit (RU) to the first P2P STA for DiL communication and allocating one or more uplink (UL) RUS for UL communication during a specified UL duration, and
during the specified UL duration, transmitting, to a second P2P STA, a first frame over a first part of the allocated DiL RU; and
receiving a second frame from the second P2P STA over a second part of the DiL RU, wherein the first part and the second part are time-multiplexed and separated by a short interframe space, SIFS, and wherein the transmitting of the first frame is configured such that an end of transmission of the second frame by the second P2P STA aligns in time with an end of the specified UL duration.
2 . The method of claim 1 , wherein one RU that is immediately adjacent in frequency to the DiL RU is defined in the triggering frame to remain empty during the UL duration.
3 . The method of claim 1 , further comprising, at the first P2P STA, sensing an acknowledgment, ACK, frame sent by the AP on the DiL RU, after the specified UL duration and, in case no ACK frame is sensed, transmitting energy over the DiL RU for a time remaining after the UL duration given the TXOP.
4 . The method of claim 1 , further comprising setting the length of the first frame by:
calculating a time TXTIME1 available for the first P2P STA to transmit a physical protocol data unit (PPDU) comprising the first frame based on a time of transmitting the second frame; and
deriving a data length of the first frame based on the obtained time TXTIME1 and at least one transmission parameter, such as a modulation and coding scheme (MCS) used for transmitting the first frame,
wherein TXTIME1 is calculated as TXTIME0-TXTIME2-SIFS, where:
TXTIME0 is computed from the UL duration specified in the triggering frame, and
TXTIME2 is the time required to the second P2P STA to transmit a physical protocol data unit (PPDU) comprising the second frame.
5 . The method of claim 1 , wherein the second frame is a response frame to the first frame, preferably an acknowledgement (ACK) frame sent by the second P2P STA for acknowledging reception of the first frame.
6 . The method of claim 1 , wherein the one or more UL RUs belongs to a set of RUs defined, in the triggering frame, to be adjacent, in frequency, to the DiL RU.
7 . The method of claim 1 , wherein the allocated DiL RU is an n*20 MHz channel, with n a positive integer.
8 . The method of claim 1 , wherein the triggering frame is a trigger frame received from the AP or a data or control frame received from the AP that includes a trigger resource scheduling (TRS) field.
9 . A communication device in a wireless network, capable of operating as a first peer-to-peer (P2P) station (STA), the communication device comprising:
one or more processors; and
one or more memories storing instructions that, when executed by the one or more processors, cause the communication device to:
receive, from an access point (AP), a triggering frame reserving a transmission opportunity (TXOP), the triggering frame allocating one direct link (DiL) resource unit (RU) to the first P2P STA for DiL communication and allocating one or more uplink (UL) RUs for UL communication during a specified UL duration;
during the specified UL duration, transmit, to a second P2P STA, a first frame over a first part of the allocated DiL RU; and
receive a second frame from the second P2P STA over a second part of the DiL RU, wherein the first part and the second part are time-multiplexed and separated by a short interframe space, SIFS, and wherein the transmitting of the first frame is configured such that an end of transmission of the second frame by the second P2P STA aligns in time with an end of the specified UL duration.