Lattice Decoding for Joint Detection in Direct Sequence CDMA Systems*

            
  
   

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1E+00 SphDec : User 1 SphDec : User 2 SphDec : User 3 SphDec : User 4 PIC : User 1 PIC : User 2 PIC : User 3 PIC : User 4 Single User BPSK

BER

1E-01

1E-02

1E-03

1E-04 -10

-5

0 5 SNR2 = SNR3 = SNR4 (dB)

10

15

5 *&     & *   E1F    /@3 < 0 E (      1     

',

1E+00

1E-01

BER

1E-02

1E-03 SphDec : User 1 SphDec : Worst User SphDec : Best User DF-MMSE: User 1 DF-MMSE: Worst User DF-MMSE: Best User Single User 16-PAM

1E-04

5

10 15 20 SNR2 = SNR3 = SNR4 = SNR5 = SNR6 = SNR7 (dB)

25

5 +&     & 0   3,"1    /@3 < 37 E

'0

1E-01

1E-02

Average BER

1E-03

1E-04

1E-05

1E-06

1E-07 16

SphDec : 63 users, SF=63, Gold SphDec : 63 users, SF=63, highly correlated Single User 16-PAM

17

18 19 20 21 22 SNR1 = SNR2 = ... = SNR62 = SNR63 (dB)

23

24

5 ,&     & ,(   3,"1   

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1E+00

1E-01

BER

1E-02

1E-03 SphDec : User 1 SphDec : User 2 SphDec : User 3 PIC : User 1 PIC : User 2 PIC : User 3 ML : User 1 ML : User 3 Single User BPSK

1E-04

1E-05 -10

-5

0

5 10 SNR2 = SNR3 = SNR4 (dB)

15

20

5 0&     & *   E1F    /@3 < 0 E (      1     

'7

1E+00

1E-01

BER

1E-02

1E-03 SphDec : User 1 SphDec : Best User SphDec : Worst User DF-MMSE: User 1 DF-MMSE: Best User DF-MMSE: Worst User ML : User 1 ML : Worst User Single User 4-PAM

1E-04

1

6 11 16 SNR2 = SNR3 = SNR4 = SNR5 = SNR6 = SNR7 (dB)

21

5 ;&     & 0   *"1    /@3 < 33 E

(=

1

Total gain γ’(S) (dB)

0

-1

-2

-3 Simulation gain (∆SNR = 0 dB) Theoritical gain (∆SNR = 0 dB) Simulation gain (∆SNR = 3 dB) Theoritical gain (∆SNR = 3 dB)

-4

-5 0

0.1

0.2

0.3

0.4 0.5 0.6 Cross-correlation β

0.7

0.8

0.9

1

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