Joint communication and sensing method and related user equipment for orthogonal frequency domain multiplexing communication system

1 . A joint communication and sensing method for an orthogonal frequency domain multiplexing (OFDM) communication system, comprising:

determining a staggering offset format for an OFDM reference signal (RS) symbol; and

eliminating a time delay ambiguity in a two-dimension (2D) range with the determined staggering offset format;

wherein the OFDM RS symbol is of a comb structure;

wherein S sub unit in a subcarrier number denotes a spacing of a plurality of non-zero resource elements (RE) in a frequency domain, S sym unit in a symbol number denotes the spacing of the RS symbol in the time domain, F i unit in a subcarrier numbers denotes a staggering offset in the frequency domain of an i th RS symbol, T s denotes an OFDM duration, T cp denotes a cyclic prefix (CP) duration, and T=T s +T cp denotes a sum of the OFDM symbol duration and the CP duration.

2 . The joint communication and sensing method of claim 1 , wherein mod (Z, S sub ) ∈ {0,1, . . . S sub -1} for any integer Z is defined, where mod is a modulo operation; a first staggering scheme of the staggering offset format satisfies F i =mod (p·i+β 1 , S sub ), where p is a relative prime to S sub and β 1 ∈ {0,1, . . . S sub -1}, i=0,1, . . . ; a second staggering scheme of the staggering offset format satisfies F i sequence different from the first staggering scheme.

3 . The joint communication and sensing method of claim 2 , wherein a plurality of side peak locations are

(

τ

+

lT

s

S

sub

,

f

+

pl

S

sub

⁢

S

sym

⁢

T

+

k

S

sym

⁢

T

)

in a 2D ambiguity function, except that there are no side peaks at

(

τ

,

f

±

1

T

)

,

where 1=−S sub , −(S sub -1), . . . 0, . . . S sub -1, S sub , k ∈ , and (k,l)≠(0,0) for a delay and sum algorithm in the 2D ambiguity function with a true delay and Doppler pair at (τ, f), when the staggering offset format satisfies the first staggering scheme.

4 . The joint communication and sensing method of claim 2 , wherein a plurality of side peak locations are

(

τ

+

lT

s

S

sub

,

f

+

pl

S

sub

⁢

S

sym

⁢

T

+

k

S

sym

⁢

T

)

in a 2D ambiguity function, where l=−S sub , −(S sub -1), . . . 0, . . . S sub -1, S sub , k ∈ , and (k,l)≠(0,0) for a periodogram-based algorithm in the 2D ambiguity function with a true delay and Doppler pair at (τ, f)), when the staggering offset format satisfies the first staggering scheme.

5 . The joint communication and sensing method of claim 2 , wherein the 2D unambiguous range for delay and Doppler is extended by slicing off at least a low-power side peak, when the staggering offset format satisfies the second staggering scheme.

6 . The joint communication and sensing method of claim 2 , wherein an iterative algorithm CLEAN is utilized for eliminating an impact of at least a side peak by deducting a strongest target from a cost function and removing its associated side peak with lower power, when the staggering offset format satisfies the second staggering scheme.

7 . A user equipment (UE) of an orthogonal frequency domain multiplexing (OFDM) communication system, comprising:

a wireless transceiver, configured to perform wireless transmission and reception to and from a service network; and

a controller, configured to determine a staggering offset format for an OFDM reference signal (RS) symbol; and eliminate a time delay ambiguity in a two-dimension (2D) range with the determined staggering offset format;

wherein the OFDM RS symbol is of a comb structure;

wherein S sub unit in a subcarrier number denotes a spacing of a plurality of non-zero resource elements (RE) in a frequency domain, S sym unit in a symbol number denotes the spacing of the RS symbol in the time domain, F i unit in a subcarrier numbers denotes a staggering offset in the frequency domain of an i th RS symbol, T s denotes an OFDM duration, T cp denotes a cyclic prefix (CP) duration, and T=T s +T cp denotes a sum of the OFDM symbol duration and the CP duration.

8 . The UE of an OFDM communication system of claim 7 , wherein mod (Z, S sub ) ∈ {0,1, . . . S sub -1} for any integer Z is defined, where mod is a modulo operation; a first staggering scheme of the staggering offset format satisfies F i =mod (p·i+β 1 , S sub ), where p is a relative prime to S sub and β 1 ∈ {0,1, . . . S sub -1}, i=0,1, . . . ; a second staggering scheme of the staggering offset format satisfies F i sequence different from the first staggering scheme.

9 . The UE of an OFDM communication system of claim 8 , wherein a plurality of side peak locations are

(

τ

+

lT

s

S

sub

,

f

+

pl

S

sub

⁢

S

sym

⁢

T

+

k

S

sym

⁢

T

)

in a 2D ambiguity function, except that there are no side peaks at

(

τ

,

f

±

1

T

)

,

where l=−S sub , −(S sub -1), . . . 0, . . . S sub -1, S sub , k ∈ , and (k,l)≠(0,0) for a delay and sum algorithm in the 2D ambiguity function with a true delay and Doppler pair at (τ, f), when the staggering offset format satisfies the first staggering scheme.

10 . The UE of an OFDM communication system of claim 8 , wherein a plurality of peak locations are

(

τ

+

lT

s

S

sub

,

f

+

pl

S

sub

⁢

S

sym

⁢

T

+

k

S

sym

⁢

T

)

in a 2D ambiguity function, where 1=−S sub , −(S sub -1), . . . 0, . . . S sub -1, S sub , k ∈ , and (k,l)≠(0,0) for a periodogram-based algorithm in the 2D ambiguity function with a true delay and Doppler pair at (τ, f),), when the staggering offset format satisfies the first staggering scheme.

11 . The UE of an OFDM communication system of claim 8 , wherein the 2D unambiguous range for delay and Doppler is extended by slicing off at least a low-power side peak, when the staggering offset format satisfies the second staggering scheme.

12 . The UE of an OFDM communication system of claim 8 , wherein an iterative algorithm CLEAN is utilized for eliminating an impact of at least a side peak by deducting a strongest target from a cost function and removing its associated side peak with lower power, when the staggering offset format satisfies the second staggering scheme.