Digital Signal Processing Reference
In-Depth Information
10
0
MC−ISR (MAI Only)
MC−ISR
10
−1
5%
10
−2
10
−3
0
1
2
3
4
5
6
7
8
9
10
SNR in dB
FIgure 10.7
BER versus SNR in dB of MT-CDMA MC-ISR,
L
= 64,
N
c
= 3,
C
= 8,
with and
without full interference suppression (i.e., with and without ICI suppression).
interference suppression (i.e., with and without ICI suppression). Figure 10.7 shows that
MC-ISR with full interference rejection is required to improve the system performance.
Indeed, at a bit error rate of 5%, MC-ISR with full interference suppression performs
1.2 dB better than MC-ISR with MAI suppression only. In order to capture in more
detail the gains achieved by ICI suppression in MC-CDMA, we proceed in
Figure 10.8
to additional comparisons between the link-level BER performances of MC-ISR and
MC-MRC in a single-user context (i.e.,
C
= 1, no MAI, only ICI, and negligible ISI). Start-
ing from the reference situation of Figure 10.8a with
L
= 64,
N
c
= 7, and DBSPK where
the reported SNR gain due to ICI suppression is about 0.5 dB, the results suggest that ICI
suppression is even more advantageous at higher-rate transmissions, and increasingly so
when we move to the scenarios of Figures 10.8b-d; i.e., when we increase the number of
carriers to
N
c
= 11 (SNR gain is about 1 dB), reduce the processing gain to
L
= 32 (SNR
gain is about 3 dB), or increase the modulation order to D8PSK (SNR gain far exceeds 5
dB if not infinite), respectively. These results further confirm the benefits of ICI rejection
in a full interference suppression scheme using MC-ISR.*
10.4.4
MT-CDMA, MC-DS-CDMA, and DS-CDMA
Performance Comparison
This section is dedicated to the performance comparison of the proposed MC-ISR
receiver with two potential next-generation multicarrier CDMA-air interface configu-
rations: MT-CDMA and MC-DS-CDMA. Single-carrier ISR [42] for 3G DS-CDMA-air
* Simulation results performed in the framework of this contribution and reported in [50] show
that the ICI rejection is even more beneficial in the case of one receiving antenna (
M
= 1).
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