Search

In Near Vertical Incidence Skywave (NVIS) propagation, effective diversity reception can be realized using a dual channel receiver and a dual polarization antenna with polarization matched to the (left hand and right hand) circular polarization of the characteristic waves propagating in the ionosphere. This paper presents measurements on NVIS-signals received via ionospheric F-layer reflection using a dual circular polarization receive antenna, demonstrating a reduction of the fading margin by 8-11 dB over a single circular polarization antenna. The measurements where performed at a mid-latitude location in the Northern hemisphere, over a distance of 110 km.

Near Vertical Incidence Skywave (NVIS) propagation can be used to realize radio communication without the need for an intermediate network. NVIS uses the ionosphere as a reflector to cover a large area (200 × 200 km) around the transmitter, on frequencies ranging from 3 to 10 MHz. NVIS is therefore used for telecommunication in areas that lack a telecommunication infrastructure, or in areas where the existing infrastructure is destroyed by a large scale disaster, such as the 2005 flooding of New Orleans. We will give an overview of the NVIS research performed in The Netherlands.

In this report we provide the findings of the 2.4 GHz service level research. Here service level means the following: can all devices in the 2.4 GHz band fulfill their communication needs. In other words this corresponds to the overall Quality of Service (QoS). The project is a short research exploratory project of about 400 hours in collaboration with Agentschap Telecom, the Dutch Radiocommunications Agency. First of all a survey has been made to investigate which measurement methods can be used to assess the service level in the 2.4 GHz. Here the focus is on IEEE 802.11b/g/n (WiFi) systems. The service level can be measured at several levels of the OSI model: spectrum sensing (physical layer) and packet sniffers (datalink layer). Power level measurements are used to assess the utilization of the 2.4 GHz ISM band. On the other hand packet sniffers are an appropriate method to measure congestion and to pinpoint problems. Secondly, in this project the interferer mechanisms of several sources (microwave, wireless A/V transmitter, Bluetooth, second WiFi network) have been measured in a controlled environment. It turns out that interferers not only increase retry rate, but also trigger unwanted WiFi mechanisms; especially the hidden node mechanism (Request To Send (RTS)/Clear To Send (CTS) packets). So this means that the CTS/RTS control packets, but also the retry rate can be used to identify congestion. The spectrum measurement results allow to identify which interferer source causes congestion. Finally, also a measurement setup is presented that allows to measure the service level. In addition, initial measurements are provided of live environments (college room, office room, city centre). The results show inefficient use of the wireless medium in certain scenarios, due to a large frame rate of management and control packets compared to the data frame rate. In a busy WiFi environment (college room) only 20% of all frames are data frames. Of these data frames only 1/10 are actual data frames as most data frames are so-called null frames; used to keep a WiFi connection alive in power save mode. From all frames about 70% are control frames of which most are ACK frames and in less extend CTS/RTS frames. More research is required to identify the reasons for the high number of control frames. It is likely that there is significant interference, probably due to the many WiFi devices. This is also depicted by the retry frame rate (7%). Combining spectrum sensing with packet sniffing seems to be a good method to assess the service level in the 2.4 GHz ISM band. However, the interferer mechanisms that occur between WiFi networks, WiFi devices and other technologies are complex. More research is needed to enhance the developed proof-of-concept demonstrator and to have a better understanding of the interferer mechanisms in WiFi systems.

The use of mobile applications in the 800 MHz band, which forms part of the ‘Digital Dividend’, may cause interference to cable TV signals under certain conditions. The new mobile applications (called LTE, Long Term Evolution) use frequency bands also used in cable TV networks. This paper discusses the results of an investigation carried out by the Dutch Radiocommunications Agency and University of Twente. In this investigation an interference model has been derived which shows that the interference probability from mobile applications in the Digital Dividend band is low: on average 5000 Dutch households would experience interference per TV evening. In addition, we propose a number of measures for individual households that can reduce the interference probability to almost zero. Especially better cables and set top boxes or moving the LTE mobile further away from the TV are effective measures.

In dit rapport wordt een antwoord gegeven op de vraag onder welke voorwaarden vergunningshouders op een zo technisch efficiënt mogelijke manier verschillende mobiele communicatietechnologieën kunnen toepassen binnen de aan hun vergunde frequentieruimte in de 800, 900, en 1800 MHz band.

The start of use of mobile applications in the 800 MHz band, which forms part of the ‘Digital Dividend’, will cause interference to TV signals under certain conditions. The new mobile applications (called LTE, Long Term Evolution) use frequencies also used in cable TV networks. This report examines how much interference may occur when providing digital television over cable networks.

De introductie van het gebruik van mobiele toepassingen in de 800 MHz band, die onderdeel vormt van het zogenaamde digitaal dividend, leidt onder bepaalde omstandigheden tot een verstoring van tv-signalen. De nieuwe (LTE) mobiele toepassingen gebruiken frequenties die ook worden toegepast in kabel-tv-netwerken. Dit rapport gaat in op de mate waarin deze storing kan plaatsvinden in het (digitale) televisie aanbod van de kabel.

A distributed storage approach is proposed to access data reliably and to cope with node failures in wireless sensor networks. This approach is based on random linear network coding in combination with a scheduling algorithm based on backpressure. Upper bounds are provided on the maximum rate at which data can be reliably stored. Moreover, it is shown that the backpressure algorithm allows to operate the network in a decentralized fashion for any rate below this maximum.

Dynamic Spectrum Access (DSA) is an exciting new technology, which introduced a paradigm shift in spectrum access. As a result it also changes the role of the regulator. On one hand the scarce radio spectrum should be used in an optimal way, so that the society is best served. On the other hand interference between users and networks should be avoided. For that reason rules have to be defined for spectrum use. This topic is called spectrum governance. For evaluation and to check whether devices obey the rules, a monitoring network is needed. In this paper, we propose to use a fleet of mobile monitoring vehicles for this purpose.

In this paper a Raptor code is developed and applied in an opportunistic error correction (OEC) layer for Coded OFDM systems. Opportunistic error correction [3] tries to recover information when it is available with the least effort. This is achieved by using Fountain codes in a COFDM system, which means that each subcarrier contains a Fountain coded packet. The property of a Fountain code that any missing packet can be replaced by any other packet allows the receiver to discard packets with low SNR. As a result ADC resolution and therefore energy consumption can be reduced. In this paper the possibilities of using Raptor codes in an OEC system are investigated. Raptor codes are a type of Fountain codes with an efficient encoding and decoding algorithm. By simulating an OEC system on a wireless indoor channel model, it is shown that Raptor codes can save up to 70% in energy consumption with respect to a traditional system. Furthermore it is found that a feedback channel can reduce energy consumption even more. In this setting 85% of energy consumption can be saved.

There is a rat race in wireless communication to achieve higher spectral efficiency. One technique to achieve this is the use of multiple antenna systems i.e. MIMO systems. In this paper we describe a wireless 4x4 Multiple Input Multiple Output (MIMO) testbed in the 2.2 GHz band including results from live experiments. MIMO systems have several advantages compared to SISO (Single Input Single Output) systems. The most important ones are higher reliability and/or higher throughput per Herz. In this testbed we used the 802.11a OFDM Wireless LAN standard as a basis for the MIMO system. The experiments have been conducted at 2.2 GHz carrier using 5 MHz bandwidth. These can be divided into several subjects: antenna spacing experiments, effects for increasing antennas, AD accuracy and performance for different antenna topologies. Moreover, the performance of the Zero Forcing (ZF), Minimum Mean Square Error (MMSE) and Vertical Bell labs LAyered Space Time (VBLAST) have been evaluated.

Wireless networks in adjacent frequency channels can interfere each other. In this report it has been investigated how this interference can be minimized for the 2.6 GHz frequency band. The Dutch Ministry of Economic Affairs intends to issue begin 2008 spectrum licenses for this band. A good method to minimize interference is a Block Edge Mask (BEM). A BEM dictates the maximum transmit power in the awarded frequency spectrum. In practical systems it is nearly impossible to transmit only in the awarded spectrum. A small part of the transmit power is transmitted in adjacent frequency channels and also receivers have limited channel selectivity. For this reason, a BEM not only dictates the maximum in-band transmit power, but also defines the maximum transmit power outside the awarded frequency spectrum. An important parameter for constructing the BEM is frequency efficiency. The 3GPP standards and the proposals of other countries have been used as a starting point. There are two frequency bands where spectrum licenses will be issued, 2010 to 2019.7 MHz and 2500 – 2690 MHz.

DAB (Digital Audio Broadcasting) is the European successor of FM radio. Besides audio services, other services such as traffic information can be provided. An important parameter for data services is the probability of non-recognized or undetected errors in the system. To derive this probability, we propose a bound for the undetected error probability in CRC codes. In addition, results from measurements of a Single Frequency Network (SFN) in Amsterdam were used, where the University of Twente conducted a DAB field trial. The proposed error bound is compared with other error bounds from literature and the results are validated by simulations. Although the proposed bound is less tight than existing bounds, it requires no additional information about the CRC code such as the weight distribution. Moreover, the DAB standard has been extended last year by an Enhanced Packet Mode (EPM) which provides extra protection for data services. An undetected error probability for this mode is also derived. In a realistic user scenario of 10 million users, a 8 kbit/s EPM sub channel can be considered as a system without any undetected errors (Pud = 6 · 10−40). On the other hand, in a normal data sub channel, only 110 packets with undetected errors are received on average each year in the whole system (Pud = 5 · 10−13).

In the Adaptive Ad-hoc Free band Wireless communications (AAF) project, a radio system is investigated that senses its environment to detect un-utilised radio spectrum and use it for ad-hoc networking. In this paper the performance in terms of Quality of Detection (QoD) of a simple energy detection system is studied. It is shown that noise-level uncertainty poses a hard limit on the detectability of signals. In the case that sub-noise signal detection is required, a noise-level measurement function may have to be included in the system architecture.

Als eerste in Europa heeft Nederland begin december 2006 de omschakeling van analoge naar digitale ethertelevisie gemaakt. Voor de analoge FM-radio is er ook een digitale variant, T-DAB. T-DAB staat voor 'Terrestrial Digital Audio Broadcasting'. Dit artikel gaat verder in op deze techniek en de veldproef die de leerstoel 'Signalen en Systemen' in 2005/2006 heeft uitgevoerd in Amsterdam.

Between October 2004 and July 2006, the University of Twente carried out a technical T-DAB field trial in Amsterdam which was commissioned by the Dutch Ministry of Economic Affairs. For this trial, a low-power low-mast T-DAB pilot network was constructed both for band III (channel 12B) and the L-band (channel LH). This field trial provided evidence that a low-power low-mast network topology can coexist with a high-mast high-power network in an adjacent channel. Using gap fillers, the holes in the service area of the high-mast high-power network can be neutralized effectively. Other possible solutions such as a smaller vertical opening angle of the antenna system were not investigated. The minimum power level of the gap fillers should be 24 dB below the output power of the low-mast

DAB (Digital Audio Broadcasting) is a the European successor of FM radio and it can broadcast besides audio services also other services such as traffic information. In this paper the probability of non-recognized errors in the system is derived for a 8 kbit/s data subchannel using protection level EEP3-A. This is important as data services rely on error-free transmission. It has been shown that in a live DAB network, this probability is very low. For a realistic user scenario, a user will encounter on average a non-recognized packet each 100000 year.

The Adaptive Ad-hoc Free Band Wireless Communications (AAF) project is researching the possibility of using Software Defined Radio for wireless networks that needs to operate in an unknown or even hostile radio environment. Each node in the network needs to be cognitive of nearby transceivers in order to prevent radio frequency interference from and to other users and to survive jamming. So, in our system each node scans the radio spectrum to see which bands are free, so that these bands can be used for communication by the AAF network. The target application of our system is in a disaster relief wireless network. Since the chance of occurrence of a major emergency is very low, it will be very economical if the communication network of the rescue team can find free spectrum when it is needed, instead of reserving a fixed portion of the spectrum. In this paper we present a concept of a physical layer architecture of the scanning system of an AAF network node, and we will elaborate on the question of how it can be evaluated with of the shelf hardware.

This paper presents a software-defined radio testbed for the physical layer of wireless LAN standards. All baseband physical layer functions have been successfully mapped on a Pentium~4 processor that performs these functions in real-time. This has been tested in combination with a CMOS integrated wideband analog front-end containing a low noise amplifier, downconversion mixers and filters. The testbed consists of both a transmitter and a receiver. The transmitter contains a PC with a DAC board, an Agilent E4438C generator for upconversion and an antenna. The receiver consists of an antenna, a wideband analog front-end and a PC with an ADC board. On this testbed we have implemented two different types of standards, a continuous-phase-modulation based standard, Bluetooth in the 2.4 GHz band and an OFDM based standard, HiperLAN/2 in the 5 GHz band. However, as all baseband processing is performed by software, our testbed can easily be extended to other standards. To validate the SDR testbed we describe RF experiments for both Bluetooth and HiperLAN/2. In HiperLAN/2 mode, some sub-carriers are more noisy than others which is probably introduced by non-linearities in the analog frontend for example, non-linearities in the power amplifier. To investigate this effect, we have performed simulations in HiperLAN/2 mode to study these effects.

The number of wireless communication links is witnessing tremendous growth and new standards are being introduced at high pace. However, circuit development is costly and time consuming due to mask costs and design iterations. Moreover, with ever-increasing radio standard complexity, these costs are increasing. This pleads for a Software Defined Radio approach, in which one piece of flexible radio hardware is re-used for different applications and standards, downloadable and under software control. A software defined radio receiver can -at different times receive signals of a multitude of standards, obliviating the need to design, manufacture, stock and carry around separate receivers for all contemporary radio standards. The presented design includes both the analogue and the digital front-end. A CMOS integrated analogue downconverter containing a low-noise amplifier, downconversion mixers and filters performs all analogue processing required between RF pre-filters and the analogue-to-digital converter. The real-time baseband processing is partly implemented on an ASIC (channel selection) and partly on a standard PC (demodulation). Using a standard PC further enhances the flexibility of the design. The combined set-up is capable of receiving both Bluetooth and Hiperlan/2 signals. We conclude that an analog wide-band front-end with a flexible Sample-Rate Converter (SRC) combined with appropriate software on an inherently flexible PC forms a feasible architecture for Software Defined Radio.

In joint timing and carrier offset estimation algorithms for Time Division Duplexing (TDD) OFDM systems, different timing metrics are proposed to determine the beginning of a burst or symbol. In this contribution we investigated the different timing metrics in order to establish their impact on the joint time and carrier-frequency offset estimation.

In this paper we develop a blind modulation-index estimator for a combined CPM/OFDM Receiver. The performance of the estimator in an AWGN channel is assessed by simulation and analysis and its suitability for our receiver is established.

New wireless communications standards do not replace old ones, instead the number of standards keeps on increasing and by now an abundance of standards exists. Moreover there is no reason to assume that this trend will ever stop. Therefore, the software-radio concept is emerging as a potential pragmatic solution: a software implementation of the user terminal able to dynamically adapt to the radio environment in which the terminal is located. For manufacturers this could result in shorter development time, cheaper production due to higher volumes. Furthermore software radio has advantages for consumers because it enables only software updates for new functionality without new hardware. Because of the analog nature of the air interface, a software radio will always have an analog front-end. In an ideal software radio, the analog-to-digital converter (ADC) and the digital-to-analog converter (DAC) are positioned directly after the antenna. Such an implementation is not feasible due to the power that such a device would consume and other physical limitations. It is therefore a challenge to design a system that preserves most properties of the ideal software radio while being realizable with current-day technology. Such a system is called a software-defined radio (SDR). A flexible, all-standard radio will consume more energy than a dedicated radio for a single standard. The first flexible radio could be an application where power consumption is less an issue; an example being a flexible radio in a notebook. This thesis presents such a radio with the focus on wireless LAN standards. These standards use phase modulation or OFDM in the $2.4$ GHz or $5$ GHz frequency band, so we decided in our project to combine a receiver of a phase modulation standard (Bluetooth) with an OFDM receiver (HiperLAN/2) first. In our view SDR is an implementation technology: the HiperLAN/2 hardware is that complex to the Bluetooth hardware that the Bluetooth receiver may be added to the HiperLAN/2 one at limited costs. In this thesis we describe how the physical layer of the OSI model of a phase-modulation receiver can be combined with an OFDM receiver at a functional level. The second goal of this research is to investigate whether this combined receiver can be implemented in software running on a General Purpose Processor (GPP) and estimate the costs of such an implementation with respect to power consumption and computational power requirements. For this reason, a testbed has been developed where all baseband physical layer functions have been successfully mapped on a Pentium 4 processor. This has been tested in combination with a CMOS-integrated wideband analog SDR front-end, containing a low noise amplifier, down-conversion mixers and filters. The testbed can be extended to other standards, because the only limitations in our testbed are the maximal channel bandwidth of $20$ MHz, the dynamic range of the wideband SDR analog front-end and the processing capabilities of the used PC. In 1999, Bose showed for second-generation mobile standards that it is possible to perform most baseband functions of the physical layer on a GPP processor. In his research, I/O was one of the main bottlenecks. In thesis we have identified that this is no longer true for current-day computers. Nowadays, an important bottleneck is the latency of the operating system, because wireless standards require fast response times. Major contributions of this thesis to the field of SDR research are extending the work of Bose for wireless LAN standards and developing a functional SDR receiver architecture that is capable of receiving standards that use OFDM or phase modulation.

Flexible radio receivers are also called Software Defined Radios (SDRs) [1], [2]. The focus of our SDR project [3] is on designing the front end, from antenna to demodulation in bits, of a °exible, multi-standard WLAN receiver. We try to combine an instance of a (G)FSK receiver (Bluetooth) with an OFDM receiver (HiperLAN/2). This paper focusses on the integration of the two receivers. The used modulation techniques (GFSK and OFDM) are very di®erent and result therefore in different receiver structures. As HiperLAN/2 is the most demanding standard, we have used a more advanced receiver algorithm for Bluetooth reception, the MAP (Maximum A posteriori Probability) receiver. Besides the better performance of the MAP receiver, the structure of it is more similar to the HiperLAN/2 receiver. The resulting partitioning of the Bluetooth receiver functions on the HiperLAN/2 receiver parts is very balanced. As other WLAN standards use the same frequency bands and similar modulation techniques, our Bluetooth-HiperLAN/2 receiver can easily be adapted to these other WLAN standards.

For the specification of phase-noise requirements for the front-end of a HiperLAN/2 system we investigated available literature on the subject. Literature differed in several aspects. One aspect is in the type of phase-noise used (Wiener phase-noise or small-angle phase noise). A Wiener phase-noise based analysis leads to contradictions with the type of analysis normally used in the solid state oscillator literature. However, a phase-noise spectrum with a Wiener phase-noise shape can be used provided that the small-angle approximation is satisfied. An other aspect is whether a Fourier Series or DFT based approach is used. The approaches use weighting functions to relate phase-noise power spectral densities to phase-noise power. The two types of analysis are presented in a unified fashion that allows easy comparison of the weighting functions involved. It can be shown that for practical purposes results are identical. Finally phase-noise specifications for the HiperLAN/2 case are presented.

In our software-defined radio project, we aim at combining two standards luetooth and HIPERLAN/2. The HIPERLAN/2 receiver requires more computational power than Bluetooth. We choose to use this computational power also for Bluetooth and look for more advanced demodulation algorithms such as a maximum a posteriori probability (MAP) receiver. The paper discusses a simplified MAP receiver for Bluetooth GFSK signals. Laurent decomposition provides an orthogonal vector space for the MAP receiver. As the first Laurent waveform contains the most energy, we have used only this waveform for our (simplified) MAP receiver. This receiver requires a E/sub b//N/sub 0/ of about 11 dB for a BER of 10/sup -3/, required by the Bluetooth standard. This value is about 6 dB better than single bit demodulators. This performance is only met if the receiver has exact knowledge of the modulation index.

In our Software Defined Radio project we perform a feasibility study of a software defined radio for two communication standards: HiperLAN/2 and Bluetooth. In this paper the Matlab/Simulink implementation of the HiperLAN/2 demodulator for the demonstrator of the project is iscussed, with special attention for the frequency offset corrector. This type of correction is necessary to prevent large bit error rates that are caused by inter-subcarrier interference. The method that is proposed in this paper uses preamble section A to estimate the frequency offset. Simulation results for an AWGN channel show that the method is capable of correcting frequency offsets up to the boundary defined in the standard [1]. It was observed that frequency offset correction using only preamble section A is sensitive to –for example– synchronization errors in case real-life analog front-end signals are used.

In our Software-Defined-Radio (SDR) project we aim to combine two receivers (HiperLAN/2 and Bluetooth) on one common platform. In this paper, the main focus is on one of the performance bottlenecks of such a receiver, namely the bandpass filter section in Bluetooth mode. Contributions of inter-symbol interference ISI, adjacent channel interference ACI and noise on the total bit error rate BER are analyzed. The influence of the channel selection filter characteristics on these contributions are researched. Larger values for (for instance) transition bandwidth result in lower order filters that reduce the computational load, which is an important design consideration. This also reduces bit errors caused by ISI, one of the two major contributors to the total BER. On the other hand, lower order filters increase the BER due to ACI. Optimal filter parameters are derived from these trade-offs and applied the system which will be presented.

In our Software Defined Radio (SDR) project we aim at combining two different types of standards, Bluetooth and HiperLAN/2 on one common flexible hardware platform. The HiperLAN/2 hardware is that complex compared to the Bluetooth hardware, that Bluetooth capability may be added to the HiperLAN/2 platform at limited cost. The question is how to do this. In this paper we first describe the radio front-end functions and their implementation. Subsequently the test-bed that will assist us in building the hardware platform is described.We present the method by which we use the HiperLAN/2 front-end for Bluetooth reception purposes Our system consists of three parts: analog signal processing, digital channel selection and digital demodulation. The analog processing function is capable of reception of both standards.The demodulation function and channel selection function are implemented in two separate software programs (one for each standard) that allow the exploration of different design alternatives and the assessment of computational cost of the receiver.

In our Software Defined Radio SDR project we aim at combining two different types of standards, Bluetooth and HiperLAN/2 on one common hardware platform. Goal of our project is to generate knowledge about designing the front end of an SDR system (from the antenna signal to the channel bit stream) where especially an approach from both analog and digital perspective is essential. Bluetooth uses Gaussian Frequency Shift Keying (GFSK) as modulation technique. As QAM and GFSK signal can be demodulated by using the same type of algorithms, the outer receiver of HiperLAN/2 can be used as a Bluetooth demodulator. So, whereas most commercial Bluetooth chips are low cost and inflexible, in our project flexibility and re-use of hardware is important. It is for that reason that a part of the channel selection and demodulation will be done in the digital domain. The choice of the demodulation algorithm determines the channel selection requirements (better demodulation algorithms require less SNR). This work analyzes the performance of several Bluetooth (GFSK) demodulation and decision algorithms using single bit decision. A simulation model was built to measure the performance of these algorithms. In our simulation model, low-IF or zero-IF Bluetooth signals are sampled with 80 MHz to get a realistic setting. The synchronization word in the Bluetooth packet is used for bit synchronization. To obtain a BER (Bit Error Rate) of 0.1%, specified by the Bluetooth standard, the best combination of demodulation and decision algorithm requires an SNR of about 15 dB. Ongoing research focusses on several subjects: multibit decision, advanced demodulation algorithms (such as (adaptive) decision feedback equalizers) and bit-synchronization algorithms.

In our Software Defined Radio (SDR) project we aim at combining two different types of standards, Bluetooth and HiperLAN/2 on one common hardware platform. HiperLAN/2 is a high-speed Wireless LAN (WLAN) standard, whereas Bluetooth is a low-cost and low-speed Personal Area Network (PAN) standard. An SDR system is a °exible radio system that is re-programmable and reconfigurable by software in order to cope with its multi-service, multi-standard and multi-band environment. Goal of our project is to generate knowledge about designing the front end of an SDR system where especially an approach from both analog and digital perspective is essential.To what extent can we use the HiperLAN/2 receiver hardware for our Bluetooth receiver? In this paper we present a functional architecture that brings the architectural descriptions of both standards to an equal level. This SDR functional architecture is used in the sequel of the project for a number of purposes, of which we mention 1. Definition of reference points (for requirements definition purposes). 2. Definition of interfaces (potential alignment with SDR Forum). 3. Delimitation of our demonstrator (what is it that is going to be built). 4. Identification of inter-standard functional integration challenges.

The use of mobile telephony has shown a spectacular growth in the last 10 years. A side effect of this rapid growth is an excess of mobile system standards. Therefore, the Software-Defined-Radio (SDR) concept is emerging as a potential pragmatic solution: it aims to build flexible radio systems, which are multi-service, multi-standard, multiband, re-configurable and re-programmable, by software. First, this paper presents a global overview of SDR. Furthermore, it discusses several front-end architectures of SDR. The goal of this project is to generate knowledge about designing part of the functionality of SDR, implemented by rapid prototyping strategies. The focus is on the front end of SDR. The technological roadmap is taken into account to evaluate several architectures.

The discovery of Turbo Codes in 1996 by Berrou et. al. proved to be a huge boost for the research of channel coding. The Turbo Principle behind turbo codes was found to be applicable in other areas. One of these areas is Multiuser Detection. In this thesis, Turbo Multiuser Detection is investigated in order to answer two main questions. The questions concern the performance gain that is obtained when turbo multiuser detection is used instead of non-turbo multiuser detection and the convergence behavior of turbo multiuser detection. The performance gain is determined by comparing the bit-error-rate (BER) chart of a turbo multiuser detection architecture with the BER chart of a non-turbo multiuser detector. It was found that turbo multiuser detection results in a dramatical performance gain when Eb/N0 > 3 dB and more than one iteration is performed. The convergence behavior of turbo multiuser detection is analyzed with the help of EXIT charts. EXIT charts are recently proposed by S. ten Brink as a tool to analyze the convergence behavior of turbo architectures. EXIT charts are discussed in this thesis. An EXIT chart of a turbo multiuser detection architecture is created. From this chart, the minimum number of iterations to obtain the lowest BER possible are found. EXIT charts are also used to analyze the difference of iterating aposteriori and extrinsic information in a turbo architecture. The analysis shows that EXIT charts of a-posteriori information give results, which contradict the results of simulations on turbo architectures.