COMMUNICATION METHOD, REPEATER AND NETWORK DEVICE

1 . A repeater, comprising:

a mobile terminal configured to receive a first MAC CE for indicating an uplink backhaul link beam; and

a forwarding unit configured to use a spatial filter corresponding to a TCI state ID or an SRS resource ID provided by the first MAC CE for transmissions on the backhaul link.

2 . The repeater according to claim 1 , wherein,

in a case where the repeater does not simultaneously transmit on the backhaul link and a control link, the transmissions of the forwarding unit on the backhaul link uses the spatial filter corresponding to the TCI state ID or SRS resource ID provided by the first MAC CE; and

in a case where the repeater simultaneously transmits on the backhaul link and a control link, a spatial filter for transmissions on the backhaul link is same as a spatial filter for transmissions on the control link.

3 . The repeater according to claim 1 , wherein,

the first MAC CE has a fixed size and consists of a single octet, the single octet comprising a first information field used to indicate an uplink beam for backhaul link transmission and a reserved bit set to zero.

4 . The repeater according to claim 3 , wherein,

six (6) rightmost bits of the first information field contain an SRS resource ID configured in an active UL BWP, with a remaining bit set to zero.

5 . The repeater according to claim 3 , wherein,

in a case where a DL or joint TCI state list (dl-OrJoint-TCI-StateList) is configured and a unified TCI state type (unifiedTCI-StateType) is configured with a value as joint, the first information field contains a TCI state ID, comprising all 7 bits, of a Joint TCI State configured in an active DL BWP, which is used as an uplink beam indication for backhaul link transmission; and

in a case where an UL TCI state list (ul-TCI-StateList) is configured, the first information field contains a TCI UL state ID, contained in the 6 rightmost bits, of an UL TCI State configured in an active UL BWP, which is used as an uplink beam indication for backhaul link transmission, with the 1 remaining bit set to zero; and

otherwise, 6 rightmost bits of the first information field contain an SRS resource ID configured in an active UL BWP, which is used as an uplink beam indication for backhaul link transmission, with the 1 remaining bit set to zero.

6 . The repeater according to claim 1 , wherein,

the SRS resource ID is used to provide a first reference resource and/or a first reference reference signal (reference RS),

the first reference resource and/or the first reference reference signal (reference RS) comprising a PUCCH resource, and/or an SSB, and/or an NZP CSI-RS resource, and/or an SRS resource.

7 . The repeater according to claim 1 , wherein,

that the first MAC CE provides an SRS resource ID comprises that, the first MAC CE indicates an SRS resource and/or an SRS resource set.

8 . The repeater according to claim 7 , wherein,

a second reference resource and/or second reference reference signal to which the SRS resource corresponds is/are indicated by RRC signaling and/or MAC signaling.

9 . The repeater according to claim 7 , wherein the SRS resource indicated by the first MAC CE is:

periodic or semi-persistent or aperiodic; and/or,

used for beam management or codebook or non-codebook or antenna switching or PDC; and/or,

configured by third configuration information and/or fourth configuration information; and/or,

in an active uplink BWP.

10 . The repeater according to claim 7 , wherein the SRS resource indicated by the first MAC CE:

has a specific resource type; and/or,

has a specific purpose; and/or,

has specific spatial relationship information; and/or

belongs to a specific SRS resource set; and/or,

has an SRS resource identifier less than or not greater than a first value; and/or,

belongs to former N or latter N SRS resources arranged in an ascending or descending order of indices; and/or,

belongs to former N or latter N SRS resources arranged in an ascending or descending order of SRS resource identifiers.

11 . The repeater according to claim 7 , wherein,

the first MAC CE indicates the SRS resource from one or more SRS resources.

12 . The repeater according to claim 11 , wherein the one or more SRS resources:

have specific resource type; and/or,

have specific purpose; and/or,

have specific spatial relationship information; and/or

belong to a specific SRS resource set; and/or,

have SRS resource identifiers less than or not greater than a first value; and/or,

belong to former N or latter N SRS resources arranged in an ascending or descending order of indices; and/or,

belong to former N or latter N SRS resources arranged in an ascending or descending order of SRS resource identifiers.

13 . The repeater according to claim 12 , wherein,

the specific resource type comprises: periodic, or semi-persistent, or aperiodic;

the specific purpose comprises: beam management or codebook or non-codebook or antenna switching or PDC;

and the specific spatial relationship information comprises: that a corresponding second reference resource and/or second reference reference signal is/are in an active downlink BWP or uplink BWP.

14 . The repeater according to claim 12 , wherein,

the specific SRS resource set is predefined or indicated.

15 . The repeater according to claim 12 , wherein,

the specific SRS resource set is an SRS resource set indicated by the first MAC CE.

16 . The repeater according to claim 12 , wherein the specific SRS resource set:

has a specific resource type; and/or,

has a specific purpose; and/or,

has a specific SRS resource set identifier; and/or,

has a specific index; and/or,

is indicated by the first MAC CE.

17 . The repeater according to claim 16 , wherein,

the specific purpose comprises: beam management or codebook or non-codebook or antenna switching or PDC;

the specific resource type comprises: periodic, or semi-persistent, or aperiodic;

the specific SRS resource set identifier comprises: maximum or minimum SRS resource set identifier, or relatively large or small SRS resource set identifier, or SRS resource set identifier equal to a specific value;

and the specific index comprises: a first or last one in a SRS resource set configured by fourth configuration information.

18 . The repeater according to claim 7 , wherein the SRS resource set indicated by the first MAC CE is:

periodic, or semi-persistent, or aperiodic; and/or,

used for beam management or codebook or non-codebook or antenna switching or PDC; and/or,

configured by fourth configuration information; and/or,

in an active uplink BWP.

19 . A network device, comprising:

a transmitter configured to transmit a first MAC CE for indicating an uplink backhaul link beam to a repeater, the first MAC CE providing a TCI state ID or an SRS resource ID, wherein the repeater uses a spatial filter corresponding to the TCI state ID or the SRS resource ID.

20 . A communication system, comprising:

a network device configured to transmit a first MAC CE for indicating an uplink backhaul link beam to a repeater; and

the repeater configured to use a spatial filter corresponding to a TCI state ID or an SRS resource ID provided by the first MAC CE for transmission on the backhaul link.