Biomedical Engineering Reference
In-Depth Information
Fig. 6.1 Zigbee stack
Table 6.1 Zigbee at a glance
Features
Specified range
Data rate
(1) 868 MHz: 20 kbps
(2) 915 MHz: 40 m kbps
(3) 2.4 GHz: 250 kbps
Frequency bands
Physical layers at 868 MHz,
915 MHz and 2.4 GHz
Range of communication
10-1,000 m
Latency
15 ms
Channels
(1) 868/915 MHz: 11 channels
(2) 2.4 GHz: 16 channels
Addressing
Short 8 bit or 64 bit IEEE
Channel access
CSMA-CA and slotted CSMA-CA
Temperature range
-40-80 C
localization accuracy has been increased by utilizing location engine and Man-
hattan distance localization. In [ 10 ], an FPGA-based system, coupled with a
Zigbee module is used for wireless monitoring of ECG. The hardware module
consists of amplifier, filter, and AD converter and Altera EP2C35 FPGA. The
FPGA module transfers the data to the Zigbee module through the serial peripheral
interface (SPI) port. The compression in the ECG signal is achieved by linear
approximation distance threshold (LIDT) algorithm.
In [ 11 ], the authors presented a Zigbee-based any cast routing system for
wireless patient monitoring. The system detects patient fall, indoor positioning,
and ECG monitoring. When a fall event is detected, the patient module transmits a
4 s. ECG data to the receiver along with patient location information. The authors
considered traffic overhead, latencies of the transmitted messages and path
recovery, validated by experimental results. The proposed system is useful for the
monitoring of elderly patients at hospitals or home. In [ 12 ], a wireless single-
channel ECG monitor using a TI low-power microcontroller TMS430F149 cou-
pled with a Zigbee module is described. At the patient side, the acquisition module
performs the signal conditioning sends the data to the Zigbee through UART link.
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