Biomedical Engineering Reference
In-Depth Information
Table 3.3
Important simulation parameters
Parameter
Value
Total number of patients
7
Number of continuous implantable sensor nodes per patient
1
Number of periodic implantable sensor nodes per patient
1
Number of periodic wearable sensor nodes per patient
3
UWB frequency
3.5-4.5 GHz
Narrow band frequency
433.05-434.79 MHz
Table 3.4
Current/Power consumptions used for simulations
Parameter
Current/power consumption
UWB transmit
2 mW [
2
]
UWB receive
16 mA [
2
]
Narrowband receive
3.1 mA [
6
]
Sleep mode
0.2 mW
packet loss ratio, L is the total number of lost packets, S is the total number of sent
packets, E is the consumed energy at a sensor node per useful data bit sent, I is the
consumed current (A) of the sensor node, V (V) is the battery voltage, T
tx-rx
(sec) is
the sum of transmission time per data packet and reception time for acknowl-
edgments /control packets at the sensor nodes, B is the total number of useful bits
contained in above mentioned packets, K is the total number of packets sent, D is
the packet acknowledgement delay for periodic traffic, T1 is the actual time at
which the packet is acknowledged and T2 is the time at which a packet enters the
transmission queue. The total network capacity (C) in throughput calculation is
chosen such that it will represent the theoretical maximum throughput for each
sensor type transmitting at a given moment. For example, if four continuous sensor
nodes are transmitting simultaneously at a given instance, the total network
capacity (C) for the continuous sensor nodes is chosen as 20 Mbps (5 Mbps 9 4)
considering their effective data rates. Important simulation parameters are listed in
Table
3.3
. The 433 MHz ISM band with Amplitude Shift Keying (ASK) is used for
the narrow band feedback link. Narrow band specifications are chosen according to
a commercial narrowband receiver [
6
] datasheet. Average current and power
consumptions for electronics in transmitter and receiver models used in the sim-
ulations are shown in Table
3.4
. The battery voltage is assumed to be 3 V.
3.5 Simulation Results
Simulation results for the analysis of various network parameters are obtained by
running five simulations for each scenario and taking the average of each result.
From the collected statistics, it was shown that the results might vary with ±4%
accuracy from the average value.
