Biomedical Engineering Reference
In-Depth Information
On-Body High Rate Line-of-Sight Communication
Let us consider the scenario shown in Fig.
2
a. The radio communication occurs
within a maximum of 2 m (i.e., a reasonable maximum distance between devices)
around the human body.
The literature reports 60-GHz wearable textile antennas with antenna gain (
G
ANT
)
of 12 dB [
30
].
As for the achievable performance of millimetre-wave CMOS transceiver, Chen
and Niknejad [
31
] report a 60 GHz power amplifier with 1-dB output, compression
point higher than 15 dBm, and Mitomo et al. [
32
] report a complete receiver with a
total NF of 14 dB.
Thus, consider a CMOS transceiver with the following performance, achievable
with modern nano-scale CMOS technologies:
• transmitted power
P
TX
equal to 15 dBm
• receiver NF equal to 14 dB
• signal bandwidth equal to 1.76 GHz centered at 60 GHz.
Then, the receiver sensitivity (
S
) amounts to:
S
=−
174 dBm
/
Hz
+
NF
+
10
×
log
10
(
BW
)
+
SNR
=−
50 dBm
(1)
The free space path loss (
PL
) amounts to:
log
10
λ
(4
πd
)
PL
=
20
×
=
74 dB
(2)
10
8
where
λ
2m.
In the case of LOS communication, the received power (
P
RX
) is equal to:
=
f
/
c
=
5mm(
f
=
60 GHz,
c
=
3
×
m/s) and
d
=
P
RX
=
P
TX
+
2
×
G
ANT
−
PL
=−
35 dBm
(3)
Thus, the loss margin (
LM
) left for shadowing, body loss, polarization mismatch,
and other losses, is equal to:
LM
=
P
RX
−
S
=
15 dB
(4)
On-Body High Rate Nonline-of-Sight Communication
In the previous section, we considered on-body LOS communication. In spite of this,
the case offers an opportunity to derive some considerations, this communication
scenario is quite unrealistic since the position of each on-body transceiver relative
to the others varies as a consequence of the human body movements. Therefore, a
more appropriate scenario would be to consider the case in which omni-directional
Search WWH ::
Custom Search