Range measurements for MICA2 Motes conducted at IISc Airfield
^ TOPAim
To measure the communication range of MICA2 motes with 1/4 wavelength (lynx) antenna and 1/2 wavelength ground plane. The area of the ground plane is 34.5 cm x 34.5 cm. The measurement includes Received Signal Strength Indicator (RSSI), Bit Error Ratio (BER) and Packet Error Ratio (PER).
^ TOPExperiment Setup
The experiments were conducted in an open plain land. The antennae were placed at a height of 1.2 meters from the ground level. Transmit powers levels were set to -10, 0 and 10 dBm. The data rates at each power levels were 1, 5 and 10kbps.
Each packet transmission consists of 8 bytes of preamble, 2 bytes of SYNC and 34 bytes of data (5 bytes of header, 29 bytes of payload) and 2 bytes of CRC.
The total number of packets to be transmitted was considered by the equation:
Where n = No. of packets to be transmitted, p = Probability of bit errors and l = length of the packet
In the above equation, p was fixed to 0.001 and l = 34 * 8 = 272 bits, (considering only 34 bytes of data).
Hence, a total of 3676 packets were transmitted for each power level at different data rates.
The Trasmission rate to achieve the required data rate is shown in table below:
| Data rate (kbps) | Packets / Second | |
|---|---|---|
| 10 | 27.82 | |
| 5 | 13.71 | |
| 1 | 2.78 |
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Calculation
Packet Error Ratio (PER) is being calculated using,
Packet Error include:
(a) If the length field in packet header is in error, then complete packet is dropped.
Bit Error Ratio (BER) is being calculated using,
Data bits in error include:
(a) if a packet is dropped, all 272 bits (34 * 8) are considered to be in error
Results
The range measurement graphs for Mica2 motes with 1/4 wavelength lynx antenna with and without 1/2 wavelength Ground plane is as follows
With and Without Ground Plane for 1 kbps
The following graph show the result of RSSI vs Distance for various power levels (-10, 0 and +10 dBm) with and without the groud plane. Starting from 50 feet, the distance is increased in steps of 50 feet
Ground Plane Measurments
Data rate 5 kbps
Data rate 10 kbps
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BER
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