**1. Introduction**

314 Ultra Wideband – Current Status and Future Trends

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The Federal Communications Commission (FCC) agreed in February 2002 to allocate 7.5 GHz of spectrum, in the 3.1 GHz to 10.6 GHz frequency band, for unlicensed use of ultra wide band (UWB) devices for communication applications. The move represented a victory in a long hard-fought battle that dated back decades. With its origins in the 1960s, when it was called time-domain electromagnetics, UWB came to be denoting the operation of sending and receiving extremely short bursts of RF energy. With its outstanding ability for applications that require precision distance or positioning measurements, as well as highspeed wireless connectivity, the largest spectrum allocation ever granted by the FCC is unique because it overlaps other services in the same frequency of operation. Previous spectrum allocations for unlicensed use have opened up bandwidth dedicated to unlicensed devices based on the assumption that operation is subject to the following two conditions:


Devices using UWB spectrum operate according to similar rules, but they are subject to more stringent requirements because UWB spectrum underlays other existing licensed and unlicensed spectrum allocations. In order to optimize spectrum use and reduce interference to existing services, the FCC's regulations are very conservative and require very low emitted power.

The UWB spectrum consists of three different parts as given below:

© 2012 Taha and Ramon, 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 cited. © 2012 Taha and Ramon, 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.


The main objective of this chapter is to study the UWB coexistence with the 3G and 4G Cellular Systems. UMTS in the 2 GHz and in the 450 MHz are two examples of the 3G cellular systems while the WiMAX system is one of 4G cellular systems.

UWB Coexistence with 3G and 4G Cellular Systems 317

narrow bandwidth interference and pulsed jamming. They gave the bit error rate (BER) of

In (Hamalainen et al., 2004) the coexistence of the UWB system with IEEE802.11a and UMTS in Modified Saleh-Valenzuela Channel has been studied as well as the UWB system performance in the presence of multiband interference. The interference sources considered were WiFi and UMTS operating simultaneously with their maximum system bandwidths. The UWB system under consideration was single band and single user operating at a data rate of 100 Mbps without error correction coding. They gave the bit error rate (BER) of the

The interference between the UMTS and the UWB systems has been studied in (Giuliano et al, 2003). The free space propagation model was used to calculate the UWB signal propagation loss. It has been concluded that the minimum allowable central frequency value for UWB device, transmitting at 100 Mbps, has to be 3.5 GHz in order to avoid harmful interference with UMTS. In (Hamalainen et al., 2001a), the effect of the in band interference caused by different types of UWB signal to the UMTS/WCDMA uplink and downlink was investigated. UWB frequency spectra have been produced by using several types of narrow pulse waveforms. They have concluded that one can reduce interfering UWB power by using different waveforms and pulse widths avoiding the UMTS frequencies without any additional filtering. In (Hamalainen et al., 2001 b) the effect of the in band interference power caused by three different types of UWB signals to GPS L1 and GSM-900 uplink band was studied. UWB frequency spectra were generated again using several types of narrow pulse waveforms based on Gaussian pulse. In band interference power has been calculated over the IF bandwidth of the two victim receivers as a function of

UWB system for different types of modulation (Direct Sequence and Time Hopping).

the UWB pulse width. Also the signal attenuation with distance was presented.

shadowing factor within the propagation loss model).

wavelet based pulse spectral shaping have been presented.

In (Ahmed et al., 2004) the effect of the UWB on the DCS-1800 and GSM-900 macrocell downlink absolute range, using the Line of Sight propagation model between the UWB transmitter and the mobile receiver, was studied (without taking into account the

The effect of the UWB emission on the UMTS and CDMA-450 macrocell downlink performance (range and capacity) has been given in (Ahmed et al., 2008). The effect of the UWB emission on the WiMAX macrocell downlink range has been studied by (Ahmed et al., 2010). In (Chiani et. al., 2009) an overview about the coexistence between UWB and narrowband wireless communication systems has been presented. In (Chóliz et. al., 2011) the coexistence between UMTS and UWB has been evaluated and cooperative mitigation techniques have been proposed and implemented. In (Das et. al., 2010) an interference cancellation schemes in UWB systems used in wireless personal area network based on

The effect of the UWB on fixed service system (point to point and Fixed Wireless Access (FWA) systems in bands from 1 to 6 GHz) has been investigated in (ITU, 2003). It was concluded that, when the UWB transmitter is in LOS with the two systems antennas, the

effect is very high when the UWB power density is higher than -41.3 dBm/MHz.

the above mentioned systems for different pulse length.

WiMAX (Worldwide Interoperability for Microwave Access) is a 4G wideband cellular communication system that can provide up to 70 Mbps in 20 MHz bandwidth. The spectrum of WiMAX at 3.5 GHz lies between 3300 to 3800 MHz. Thus, WiMAX receivers are affected by UWB interference from the UWB main part spectrum. For WiMAX at 2.5 GHz, the spectrum lies between 2300 to 2700 MHz. In this case, WiMAX receivers are affected by the interference from the lower residual part of the UWB spectrum. Table 1 shows the WiMAX modulation schemes and the necessary Signal to Interference and Noise Ratio (SINR) required to support them.

The UMTS (Universal Mobile Telecommunications System) is a 3G cellular system that can support voice, data and video services. The downlink frequency used by the UMTS systems lies between 2110 to 2170 MHz.

Deployment of UWB systems creates a "forbidden zone" around the UWB transmitter in which the receivers of WiMAX or UMTS systems can be drastically affected. In practice, the radius of the forbidden zone should be the minimum possible. In our work we will consider a forbidden zone within 1 to 2 m radius (other values such as 0.5 m can be considered) assuming that the maximum accepted downlink range reduction of the WiMAX systems at any moment is 1%. The maximum accepted reduction of the capacity of UMTS systems is assumed to be also 1%.


**Table 1.** WiMAX Modulation Schemes.
