**6. References**

46 Will-be-set-by-IN-TECH

introduce a closed form expression for the energy detection receiver with *M*-PAM. The result also contains the possibility to analyse the effect of correlated fading gains. This is the case in typical UWB wireless channels. If the fading gains are not *Rayleigh* distributed, we present a numerical solution for any fading distributions. The results of the first part enable a precise

Since the MIR-UWB system is highly sensitive to interference, the second part of the chapter

The first aspect deals with the analysis of the interference robustness of an OOK and BPPM specific energy detection receiver being the essential component of the non-coherent MIR-UWB receiver. Thereby, taking into account thermal noise a general frame work is presented which can be used to give statements on the detector's interference robustness for an interference with arbitrary bandwidth. Furthermore, possible system parameters can be

The second aspect considers the coexistence capability of the MIR-UWB system. Thereby, various easy-to-realise adaptive coexistence-based approaches are presented. Starting with a static coexistence approach a DAA coexistence approach for temporary NBI is presented being integrated into the system specific initialisation and data phase. The proposed method allows a reliable adaptive mitigation of temporary NBI. A further adaptive coexistence approach bases on image-based thresholding which can be integrated into the initialisation phase of the MIR-UWB system. Based on an exemplary interference scenario the potential to efficiently

Lastly, the third aspect focuses on the analytical investigation of the potential to mitigate NBI inside an energy detection receiver. Hereby, the TK operation as well as a modified TK operation is analysed. It is shown that for a narrowband baseband signal the output of the TK operation is characterised by a larger energy concentration in the lower frequency range. In contrast, for the modified TK operation further spectral components occur for higher frequencies. A subsequent analysis of one NBI in the bandpass domain shows that the TK operation acts like a frequency-to-DC shifter. This reveals the potential to mitigate a single NBI without the knowledge of the NBI's carrier frequency. In contrast, for the modified TK operation additional spectral components at twice the NBI's carrier frequency occur making interference mitigation critical. In case of multiple NBI further spectral components occur at the TK operation's output which can be ascribed to the mutual interference influences. Due to a possible distribution of the spectral components within the total MIR-UWB subband interference mitigation depends on the interference position inside the MIR-UWB subband.

This work was supported within the priority program No. 1202 (UKoLoS) by the German

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**Acknowledgements**

**Author details**

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**1. Introduction**

María Dolores Pérez Guirao

http://dx.doi.org/10.5772/52497

power wireless networks.

cited.

standard.

The growing request for low-to-medium data rate low cost networks is raising the interest in wireless sensor networking. For instance in the field of industrial and logistic applications, in order to improve the processes' efficiency the tight monitoring of goods, tools, and machinery -as to their state and position- is required. In response to this interest, IEEE approved in 2003 the IEEE 802.15.4 standard, this being the first one for low data rate, low complexity, and low

**Pulse Rate Control for Low Power and Low Data** 

**Chapter 2**

**Rate Ultra Wideband Networks** 

Additional information is available at the end of the chapter

The market success of wireless sensor networks (WSN) requires inexpensive devices with low power consumption. In order to satisfy this requirement, transmission technology, protocol as well as hardware design must give a common answer. UWB radio, particularly with impulse radio transmission (IR), is especially suitable for the development of WSN. IR-UWB is expected to allow low power, low complexity and low cost implementation as well as centimeter accuracy in ranging. The low complexity and low cost characteristics arise from the essentially baseband nature of the signal transmission. The high ranging accuracy results from the large absolute bandwidth, which must be at least 500 MHz. Indeed, the introduction of ranging functionality in low data rate networks was one of the main reasons for the IEEE 802.15.4a (2007) amendment, which added an IR-UWB physical layer to the original

IEEE 802.15.4a allows for the use of non-coherent receivers, and defines ALOHA<sup>1</sup> as the mandatory medium access control (MAC) protocol. The use of a non-coherent receiver, such as an energy detector, helps to minimise power consumption and reduces implementation complexity. The choice of ALOHA is justified by the potential robustness of IR-UWB to multi-user interference (MUI) and by the low data rate nature of the applications envisioned. In fact, the design of the MAC layer plays a very important role in order to materialize the benefits of IR-UWB in sensor networks. From a networking perspective, one potential <sup>1</sup> Random medium access scheme that does not check whether the shared medium is already busy before transmission.

> ©2013 Pérez Guirao, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly

©2013 Pérez Guirao, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
