Wireless body area network (WBAN) is a key technology to prevent the occurrence of myocardial infarction, monitoring episodic events or any other abnormal condition and can be used for long term monitoring of patients. The seamless integration of small and intelligent wireless sensors is used to monitor the patient’s vital signs and provide real-time feedback. They are used to develop a smart and affordable healthcare system and can be a part of diagnostic procedure, maintenance of chronic condition, supervised recovery from a surgical procedure and to monitor effects of drugs therapy. A WBAN usually consists of three levels. The first level is called sensor level, which consists of low power miniaturised sensors such as electrocardiogram (ECG)-used to monitor electrical activity of heart, oxygen saturation sensor (SpO2)-used to measure the level of oxygen, electromyography (EMG)-used to monitor muscle’s activity and electroencephalography (EEG)-used to monitor brain’s electrical activity. The second level comprises of a PDA or central intelligent node, which gathers vital information of a patient and communicates with a remote station. The third level consists of a remote base station, which keeps patient medical records and provides diagnostic recommendations.
On the other hand, ultra-wideband (UWB) technology has gained much attention during the last few years as a potential candidte for future wireless short-range data communication. FCC has already alocated the spectrum from 3.1 GHz to 10.6 GHz for UWB applications. Due to its large bandwidth UWB has the promise of high data rates. A particular type of UWB communication is impulse radio, where very short transient pulses are transmitted rather than a modulated carrier. Consequently, the spectrum is spread over several GHz, complying with the definition of UWB. Currently, the rake receiver is considered to be a very promising candidate for UWB reception, due to its capability of collecting multipath components. However, perfect synchronization can never be accomplished. Another issue is the matching of the template with the received pulse. Moreover, often a lot of rake fingers are required to accommodate the wireless channel, rendering it riot favorable from an implementation point of view. Indeed low complexity rake receivers are being investigated. The transmitted reference (TR) scheme proposed by Hoctor and Tamlinson does not suffer from the above problems and requires fewer RF building blocks compared to the multiple finger rake receiver. The core part of the transmitted reference scheme receiver, alternatively known as “autocorrelation receiver in which TR scheme can be implemented by transmitting pair of identical pulses (called doublets) separated by a time interval D, known to both receiver and transmitter.The transmitted data is encoded by relative phases of tow pulses. The first pulse act as reference and the second pulse is the modulated one. The receiver delays the first pulse by the delay D, multiplies it with the second pulse and integrates the result over one delay length, which in fact correlates the two pulses. When using polar NRZ modulation, for a logical zero, a pulse is transmitted, subsequently followed by a polarity reversed pulse. To send a logical one, two pulses with the same polarity are sent sequentially. The absolute value of the output after integration is in fact the energy of the pulse while the polarity of the output contains the data. If the output is negative, this corresponds to a logical zero, which a positive output corresponds to a logical one. Thus, the information is in the relative polarity of the two pulses and the delay between them acts as a synchronization mechanism. As long as the two consecutive pulses have corresponding waveforms except for their polarity, the autocorrelation receiver can detect them properly.Further mathematical Analysis shows that TR based UWB receiver can be used as low power receiving technology for WBAN.
In Fact, we the members of Telecommunication Engineering Research Lab have alreday contributed to the development of WBAN Technology and efforts are continuosly going on. I feel happy to put small contribution to this technology from myself also.