Biomedical Engineering Reference
In-Depth Information
Table 7
Diversity parameters for five different links at Loc. 2 (as shown in Fig.
3
) with different
spacings between diversity antennas in an indoor environment
Links
Results
Antenna spacing (in terms of
λ
0
)
0.23
0.34
0.48
0.58
Chest
MRC (dB)
9.98
11.22
11.20
11.98
EGC (dB)
8.26
10.63
10.64
10.92
SC (dB)
8.01
9.79
9.65
10.01
0.098
0.065
0.064
0.058
ρ
e
Imbalance (dB)
4.98
3.09
3.13
3.02
Head
MRC (dB)
11.12
13.08
13.06
14.24
EGC (dB)
9.89
11.97
11.90
13.01
SC (dB)
9.48
11.12
11.01
11.98
ρ
e
0.112
0.071
0.070
0.078
Imbalance (dB)
3.34
2.39
2.39
2.01
Wrist
MRC (dB)
10.42
11.90
12.04
13.14
EGC (dB)
10.01
11.33
11.36
12.02
SC (dB)
9.46
10.39
10.68
11.18
ρ
e
0.164
0.085
0.073
0.051
Imbalance (dB)
5.02
4.03
4.01
3.98
Ankle
MRC(dB)
9.92
11
10.98
11.58
EGC (dB)
9.07
10.44
10.34
10.92
SC (dB)
8.24
10.04
10.01
10.58
ρ
e
0.186
0.114
0.112
0.098
Imbalance (dB)
5.32
4.63
4.68
4.13
Back
MRC (dB)
13.01
14.28
14.13
14.98
EGC (dB)
11.84
12.62
12.61
13.04
SC (dB)
10.12
11.72
11.68
12.52
ρ
e
0.089
0.033
0.029
0.030
Imbalance (dB)
1.96
1.60
1.63
1.12
EGC
equal-gain combining,
MRC
maximum-ratio combining,
SC
selection combining
Figure
6
shows the relationship between correlation coefficient, power imbal-
ance, DG using MRC and spacing between diversity branch antennas (when Rx
is placed at wrist). From the Fig.
6
, it is obvious that DG is linked to spacing
between diversity branch antennas and it also depends on correlation and power
imbalance. Results show that DG is approximately directly proportional to spacing
between diversity branch antennas and inversely proportional to power imbalance
and correlation coefficient.
Uplink and Downlink Diversity Comparison
Uplink and downlink diversity performance has been compared by swapping Tx and
Rx antennas. For uplink diversity, Tx was off-body and diversity branch antennas
were on the body. For downlink diversity, the branch antennas were placed away
from the body and Tx was placed on the body at the same five locations as Rx
antennas for uplink diversity case. Table
8
shows MRC DG,
ρ
, power imbalance and
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