Existing approaches for multi-pitch detection have still been highly complex. In this paper, the harmonic shift algorithm (HSA) for multi-pitch detection is illustrated. The HSA is a noncoherent blind detection scheme, exploiting the constant-Q transform (CQT). The only requirement for the successful application of the HSA is that all the sources are harmonic sources. Due to this simplicity, the HSA is considered viable for both single-pitch and multi-pitch detection, making its attractive for the application in other areas of signal processing. When illustrating the performance capabilities of the HSA, we demonstrate that it outperforms the state of the art regarding the computational complexity providing detection precision, accuracy and a recall factor comparable with existing schemes.

In this paper, a novel transmission scheme which is called three-dimensional modulation using beam hopping (3DModBH) and a new receiver algorithm are suggested. The new concepts improve the spectral efficiency and the reliability of the transmit signals of 5G networks by using the spatial domain of multiple small cells. The main distinguishing feature of 3DModBH transmission scheme is that it maps additional information bits by exploiting the spatial domain of multiple small cells or base stations (BSs). More specifically, the suggested 3DModBH uses the conventional two-dimensional (2-D) modulation techniques plus the spatial domain of multiple small cells or BSs to transmit the information bits, whereas the state-of-the-art transmission scheme (SoAT) uses only the conventional 2-D modulation techniques to transmit the data. We demonstrate the advantages of the novel scheme in small cell scenario under strong interference in 5G networks. We propose a new receiver algorithm to detect the transmitted information bits in practical interference limited scenario. The performance of 3DModBH scheme and the suggested receiver are compared with the SoAT in term of average bit error rate, receiver complexity, and average bits per channel use in practical 5G scenario.

Next generation long term evolution (LTE) systems evolve towards small cell networks to boost spectrum efficiency through extreme frequency reuse. To mitigate the impact of the resulting tremendous co-channel interference, advanced receivers supporting network assisted interference cancellation and suppression (NAICS) represent a promised technique to meet the ubiquitous cell edge free experience. However, as the interfering signals will reach the cell edge user equipment (UE) at varying delays, unsynchronized small cell networks might experience large timing offsets (TOs) and considerably limit the expected downlink (DL) performance. In this paper we focus on reliable channel estimation for diverse types of NAICS receivers operating in rich interfering small cell LTE networks. With analytical results we derive the impact of TOs on channel estimation, show that the promised performance of each of the NAICS receivers vanishes when neglecting the varying delays and against expectations perform worse than conventional linear interference suppression receivers. However, estimating and compensating the impact of the TOs, reliable channel estimation can be achieved and as a result the expected DL performance of each of the investigated NAICS receivers can be guaranteed in unsynchronized small cell LTE networks.

Next generation long term evolution (LTE) systems evolve towards small cell networks (SCNs) to enable the tremendous data growth through extreme frequency reuse. However, shrinking the cell size to boost the spectral efficiency comes at the expense of increased co-channel interference (CCI) and is the dominant limiting factor from achieving higher network capacities. Consequently, downlink (DL) scenarios in the cell edge become particularly crucial, as the user equipment (UE) is typically surrounded with multiple interfering small cells. To overcome this limitation, in this paper we focus on cooperative interference mitigation schemes where UEs in good channel condition empower the cell edge UE to mitigate the CCI through linear precoding schemes. We provide a practical realization of the cooperative interference mitigation precoding scheme and determine the set of reference signal configuration to enable the promised performance in unsynchronized SCNs with varying timing offsets (TOs) among the receive signals. With simulation results at the link level, we show that estimating and compensating the TO reliable channel state information (CSI) can be achieved for the non- colliding CSI mapping scheme and as a result near optimum DL transmission can be achieved at the cell edge UE in practical SCNs.

Coordinated multipoint (CoMP) transmission is a key technique in 4G long term evolution (LTE) systems to provide the ubiquitous broadband communication with cell edge free experience at the user equipment (UE). However, as the transmit signals will reach the UE at several and varying delays, practical CoMP networks might experience large timing offsets (TOs), imposing a significant performance loss. In this paper we focus on implicit feedback generation for practical CoMP joint processing (JP)-joint transmission (JT) networks suffering from TOs. We show that conventional implicit feedback schemes prohibit the expected gain in the downlink, getting outperformed by open-loop transmission schemes and call the benefits of channel state information (CSI) feedback for CoMP JP-JT networks into question. Analytically we prove that the mapping of CSI-reference signal (RS) on different subcarriers imposes multiple phase offsets on the covariance matrix, leading to improper precoding vector selection, while imbalanced TOs among the transmitters limit coherent signal demodulation at the UE. With numerical results we show that estimating and compensating the phase offsets reliable precoding vector selection and phase feedback for coherent signal demodulation can be obtained and as a result considerable improvements for practical CoMP JP-JT networks can be achieved in presence of varying TOs.

Location services gained attraction with the recent advancements in context and location-aware technologies. Furthermore, location information becomes important with the deployment of wireless communication networks and the mobility that characterizes the wireless communication users. Within indoor environments, coverage of the explicit sensors based on Global Positioning System (GPS) is limited. Building an indoor location tracking system based on the Received Signal Strength Indicator (RSSI) of the widely deployed Wireless Local Area Network (WLAN) is considered cost effective. Extended Kalman Filter (EKF) is the most implemented algorithm for obtaining location information out of the RSSI measurements. In this paper, we propose the Spherical Simplex Unscented Kalman Filter (SSUKF) to work over WLAN IEEE 802.11n networks for indoor positioning and tracking. SSUKF exploits the RSSI measurements and the knowledge of anchor nodes' positions for location estimation. SSUKF is proposed for easy of implementation and reduced computational cost compared with EKF. Comparative results are illustrated using Monte Carlo simulations in MATLAB.

Small cell transmission is a promised technique to enable the tremendous data growth in next generation long term evolution (LTE) networks. However, emerging inter-cell interference is the dominant limiting factor achieving higher network capacities. In this paper we focus on cooperative interference mitigation techniques in interfering heterogeneous network (HetNet) deployments to assist the cell edge user equipment (UE) suffering from dominant co-channel interference (CCI). As a handover might be refused and conventional precoding matrix index (PMI) selection schemes limit reliable downlink (DL) transmission, the co-scheduled UEs being in good channel condition delegate the precoding vector selection to that victim UE. We provide a practical implementation for the cooperative interference mitigation algorithm keeping computational complexity and feedback overhead low. With numerical results at the link level we show that CCI is almost suppressed and as a result near optimum DL performance is achieved at the cell edge UE in strong interfering HetNet deployments.

The fundamental frequency (F0) is an ubiquitous and crucial feature of music signals. However, due to nonstationary noise, missing harmonics, nonideal, i.e., Undesired, physical vibration of the musical instruments, etc., the estimation of F0represents a considerable challenge when desiring to obtain robust and reliable results. In this paper, a novel harmonic pattern match (HPM) algorithm for F0estimation of music signals is proposed to achieve improved performance. The novel HPM algorithm relies on the autocorrelation both in the time domain and in the frequency domain, exploiting the spectrum subset to guide the searching of F0candidates (FCs), and an efficient mechanism to evaluate the match between each FC and the harmonic pattern of the input signal. The harmonic pattern of the measured spectrum is converted into a set of sub-pitches, which are extracted from the segmented sub bands. Finally, the estimated F0is selected to best match the sub-pitches under a weighting strategy. Validation experiments were carried out using a database representation of musical instruments consisting of single pitched notes and the viability of the HPM algorithm was demonstrated to be competitive with several other F0estimators.

Location information has become crucial in many circumstances such as rescue operations, emergencies, navigation, and tracking. Furthermore, with the deployment of the wireless communication networks and the mobility that characterizes the wireless communication users, positioning information has become a great interest. Location tracking, based on received signal strength indicators (RSSI), is a cost efficient method to gather location information. However, RSSI suffers from estimation errors due to shadowing. In this paper, a positioning framework for location tracking in WLAN IEEE 802.11n networks has been proposed which is transparent to accuracy improvement technologies. Furthermore, a novel Kalman filter implementation is presented. The implementation brings advantages over the most common approach “extended Kalman filter” in terms of computational efforts and does not require the linearization steps. The positioning framework and the proposed implementation of the Kalman filter have been evaluated on experimental data using Monte Carlo simulation.

Coordinated multipoint (CoMP) transmission is a key technique in 4G long term evolution (LTE) systems to enable broadband communication and coverage for user equipments (UEs) at the cell edge. However, as the transmit signals will reach the UE at several and varying delays, unsynchronized CoMP transmission might experience large timing offsets (TOs), imposing a significant performance loss. In this paper we focus on the impact of implicit feedback generation in closed-loop CoMP transmission operating in joint processing mode. To enable the expected advantages, reliable channel state information is crucial for practical realization of closed-loop CoMP transmission. We show that a spacing in terms of subcarriers between the reference signals in the orthogonal frequency division multiplexing symbols imposes a phase offset on the transmit covariance matrix in presence of TO, affecting the feedback generation and limiting the expected performance. We provide a solution to overcome this limitation by estimating and compensating this phase offset. We show analytically and numerically that keeping the phase offset close to zero, reliable feedback generation can be guaranteed and, as a result, near optimum performance is achieved in closed-loop CoMP transmission in unsynchronized networks with TO present.

Coordinated multipoint (CoMP) transmission is a promised candidate in long term evolution advanced (LTEA) systems to assure coverage and broadband communication for cell edge user equipments (UEs). However, the presence of timing offsets (TOs) between the received signals from multiple transmitters might limit the performance of CoMP transmission. The promised advantages of closed-loop CoMP transmission vanish for the system configuration with four transmit antennas, showing significantly poorer performance than the transmitter equipped with two antennas for large TOs. The reason is that the transmit covariance matrix used for implicit feedback generation is affected by a phase shift caused by TO after orthogonal frequency division multiplexing demodulation, leading to improper precoding matrix index (PMI) selection and therefore limiting the beamforming gain at the cell edge UE. On the other hand the system configuration with two transmit antennas is robust against that phase shift, despite the TO. Keeping the phase shift in systems with four transmit antennas low, reliable PMI selection can be guaranteed and as a result the promised CoMP transmission benefits can be achieved in a practical realization with TO present.

Coordinated multipoint (CoMP) transmission is one of key technologies to provide broadband communication and coverage for cell edge user equipments (UEs) in long term evolution (LTE) systems. The basic concept behind CoMP transmission are geographically distributed transmitters working jointly in coordinated manner. As the transmit signals reach the UE at different times, CoMP networks might experience high timing offsets (TOs) leading to a fast Fourier transform (FFT) window mismatch. Positive TOs with synchronization signals reaching the UE prior to data signals impose an acceptable performance loss, whereas the presence of negative TOs disables CoMP transmission saturating in error floor at unacceptable bit error rate. In this paper a novel approach to overcome negative TO is proposed that guaranties robust performance while keeping system complexity low. Shifting the FFT window towards the data signal by the estimated TO, the negative TO turns positive and as a result near optimum performance is achieved.

Coordinated Multipoint (CoMP) transmission is a promising technology in 4G Long Term Evolution (LTE) systems to enable coverage and high data rates for cell edge User Equipments (UEs). However, the presence of Timing Offset (TO) between the received signals from multiple transmitters at the UE could prove prohibitive for CoMP transmission. Such TO affects the estimation of the transmit covariance matrix for Pre-coding Matrix Index (PMI) selection significantly. Especially, the promised advantages of closed-loop CoMP transmission vanishes and it performs even worse than the open-loop in presence of a large TO due to the improper PMI selection. With analytical and numerical results we show that keeping the TO small, the promised advantages of closed-loop CoMP transmission can be guaranteed and as a result near optimum performance is achieved for CoMP transmission in unsynchronized networks with TO present.

In this manuscript the authors discuss the issues of designing and implementing an H-Bridge circuit with respect to small switching losses, minimal hardware afford and maximal flexibility of excitation and control. The H-Bridge is targeted for a biomedical Wireless Power Transfer (WPT) application, where the receiver (RX) is small compared to the transmitter (TX) and, thus, negligible. Resonance is applied on the TX side, while the input voltage to the H-Bridge is able to vary in the range of 3V to 28V depending on a flexible relation between the TX and RX. This causes effects to the design and the gate drivers of the H-Bridge. An H-Bridge design is proposed, which includes the use of an n-channel and p-channel Metal-Oxide Semiconductor Field-Effect Transistor (MOSFET) for a direct addressing of gates with a microcontroller (μC). In addition, the switching losses are lowered by the introduction of choke inductors and non-overlapping time delayed driving signals. Furthermore, the proposed solution has been verified, since significant advancements compared to state-of-the-art H-Bridge designs can be shown.

Coordinated Multipoint (CoMP) was adapted as a key technique to improve the coverage of high data rates and the cell-edge user experience in beyond LTE- Advanced systems. CoMP simultaneously supports multiple Transmission Points (TPs) to serve mobile devices in the high interference areas, which occur between cells. In theory it can provide significant gains in the order of high double-digit percentages for cell-edge user throughput while increasing overall network efficiency. The aim of this paper is to get an insight of the system performance and configuration flexibility of CoMP transmission in beyond LTE-Advanced systems. Different channel state information feedback concepts for CoMP networks have been analyzed theoretically and verified through Monte Carlo simulations. Complexity and implementation issues have been addressed as well. The results have shown that downlink CoMP schemes are very effective in improving the overall system performance. Furthermore, the investigation has shown that different feedback approaches bring different performance gains but also different complexity and implementation challenges. Finally, the most effective feedback approach and system configuration for CoMP scenarios investigated in this study is suggested.

The realization of cognitive radio concepts for alleviating the spectrum scarcity is of utmost interest. In particular the TV white space referring to non-occupied frequency bands in the TV spectrum has attracted many scientists. Spectrum sensing algorithms are one option to find such frequency bands. However, due to a variety of TV standards existing all over the world, different sensing algorithms are necessary to sense for TV signals. Within this manuscript, the authors present a parametrizable cognitive radio engine relying on a spectrum sensing algorithm which can easily be adapted to various TV standards. Furthermore, a cognitive radio platform is introduced and measurement results of the implemented algorithm are presented as proof of concept.

The aim of this paper is to get an insight of the interference estimation for multi-layer multi-user multiple-input and multiple-output (ML-MU-MIMO) transmission for LTE-Advanced (long term evolution) systems. Different interference-aware receivers have been investigated in ML-MU-MIMO with the presence of co-layer, intra-cell and inter-cell interferences. User-specific reference signal (UE-RS) based channel estimation and various interference covariance estimation schemes in LTE-Advanced systems are investigated together analytically and numerically. Our investigation has shown the significant influence of the interference estimation schemes on the system performance at the link level. Furthermore, the simulation results have shown the advanced MMSE receiver together with UE-RS based interference estimation as the most robust receiver structure for the signal detection in ML-MU-MIMO transmission.

In this paper, performance of location-aided transmit strategy in bidirectional relay networks over Rician fading channel is studied. This work is based on a three node relay system, where on the relay node, multiple antennas are deployed, and single antenna on other nodes. The idea of the location-aided transmit strategy is to acquire angle-of-arrival (AoA) of signal through relative location of devices, and to make use of the AoA in designing transmit beamformers. It is presented in this paper that this practical method for low-cost systems yields good system performance in terms of spectral efficiency when Line-of-Sight components exist in the propagation channel. In addition, the achievable rate performance of such relay network system in the broadcasting phase, which is impacted by Rician K-factor and the relative position between devices, are analyzed.

TV white space (TVWS) has been considered a favorable spectrum for sharing with other spectrum deficient technologies. There are three popular TV standards in China: the Digital Terrestrial Multimedia Broadcast (DTMB), China Multimedia Mobile Broadcasting (CMMB) and PAL-D/K (Phase Alternating Line -D/K). In this paper we present a prototype platform for experimental spectrum sensing, which is developed in-house to test TVWS spectrum sharing for all the three popular TV standards. We discuss the details on the prototype architecture, the spectrum sensing algorithms and the testing setup in this paper. The performance results show that the developed prototype platform can detect the signals from all the three TV standards robustly and efficiently.

The uncoded performance of an Alamouti space-frequency block code operating in a frequency-selective channel is studied in the presence of channel estimation errors. The Alamouti Maximum Likelihood (ML) symbol detector with linear combining is considered at the receiver. Imperfect channel estimates are provided by a realistic Wiener interpolator. The impact of channel estimation errors and correlation mismatch on the uncoded performance of the system is evaluated as a function of key system parameters, such as the anticipated power delay profile at the channel estimator, the actual, i.e. true, power delay profile, the pilot spacing and the Wiener filter length. The role of partial knowledge of the channel statistics is investigated as well.

In this paper, a two-step communication protocol combined with virtual MIMO (Multiple Input Multiple Output) and network coding technique is proposed. The protocol is therefore termed MINEC (MIMO Network Coding). A three nodes network with multi-antennas on relay node is taken as an illustrative example of MINEC. Theoretical and simulative analyses of the MINEC performance under the assumption of a binary symmetric relay channel model are carried out. It is found that MINEC performs equivalent to a 2 × 2 V-BLAST MIMO and a two 2 × 1 Alamouti MISO in transmitting phase and forwarding phase, respectively. Theoretical and simulative analyses prove that MINEC protocol facilitates more reliable transmission and higher throughput.

This paper will give a detailed discussion about the authors view on Software Defined and Cognitive Radio. After an introduction on different aspects of software radio a novel approach on cognitive radio is presented. As proof of concept a software defined cognitive radio demonstrator termed Falcon was built up which is described afterwards. The Falcon is entirely based on a modular signal processing concept. In particular, the receiver deploys modules which process and generate log-likelihood ratio (LLR) signals, hence, providing the capability of a plug-and-play-type reconfigurability. To the best knowledge of the authors, such a reconfigurability approach has not yet been adopted as consequently as described in this contribution before.

Cooperation in wireless networks will facilitate a new dimension in the evolution of multimedia communications, setting out from the today's situation with a multitude of communication standards and radio interfaces both in the licensed and the unlicensed domain. In order to pave the way towards cooperative networks, the deployment of cognitive wireless solutions, which will form the communication platforms, will be a hey asset. In the future, we expect to see an increasingly flexible, ad-hoc utilization of the available spectrum in the unlicensed domain and a co-exsitence of communication standards in the licensed bands. In this communication, the authors will illustrate a platform based approach towards cognitive wireless communications. Also, three software defined radio concepts designed by the authors was presented, namely the HAWK (highly adaptable wireless kit), the FALCON (flexible access logic for communication networks), and the MUSTANG (multi-standard single chip transceiver for the next generation), finally, giving an outlook on their wireless optical communication device, termed ARGOS. HAWK, FALCON, MUSTANG and ARGOS form the basis of the authors' cognitive wireless platform, termed PROMETHEUS. The setup of PROMETHEUS and its functionality shall be illustrated.

Cooperative wireless networks will facilitate a beneficial evolution of multimedia communications, setting out from the today's multitude of communication standards and radio interfaces both in the licensed and the unlicensed domain. The deployment of cognitive wireless solutions, which will form the communication platforms, will be a key asset because we expect to see an increasingly flexible, ad-hoc utilization of the available spectrum in the unlicensed domain and a co-existence of communication standards in the licensed bands. In this communication, the authors will illustrate a platform based approach towards cognitive wireless communications. Three software defined radio concepts designed by the authors will be presented, namely the HAWK (Highly Adaptable Wireless Kit), the FALCON (Flexible Access Logic for Communication Networks), and the MUSTANG (MUlti-STAndard single chip transceiver for the Next Generation), finally, giving an outlook on their wireless optical communication device, termed ARGOS. These concepts form the basis of the authors' cognitive wireless termed PROMETHEUS.

This communication discusses implementation aspects of a novel, fast iterative tap amplitude and delay estimation (ITADE) technique for RAKE receivers required for the downlink in the universal mobile telecommunications system (UMTS) frequency domain duplex (FDD) mode wideband code division multiple access (WCDMA). The Texas Instruments TMS320C6416 digital signal processor (DSP), operating at 720 MHz clock rate, is taken as the target hardware. The manuscript shall primarily focus on a sliding correlation-based ITADE algorithm developed by the authors. This algorithm shall be abbreviated by CITADE. The implementation of the CITADE algorithm exploits both the hierarchical structure of the primary synchronisation channel code, which is used as a reference for the TADE strategy, and the tailored instructions of the TMS320C6416 DSP. The found implementation requires 809 kilocycles or, equivalently, ≃1.1 ms of processing time. This processing time corresponds to a duration of ≃1.7 time slots. The presented proposal is considered a competitive design with a better performance regarding the number of required processor cycles compared to previously published work.

In the recent years, iterative ("turbo") processing techniques with soft-in/soft-out components have received considerable attention. Examples are turbo decoding, turbo equalization, and turbo multi-user detection. The authors shall consider the application of turbo-codes to environments with impulsive white noise. Impulsive noise has a nonGaussian nature and is e.g. found in many wireless channels due to impulsive phenomena of radio-frequency interference and also in power line and in digital subscriber line communication systems. A detector/turbo decoder concept, derived from turbo equalization, shall be presented. The illustrated concept avoids numerical instabilities. It shall be shown that turbo-codes facilitate considerable performance improvements over noncoded systems. Furthermore, for benchmarking reasons, the deployment of a conventional rate 1/2 convolutional code with constraint length 5 and octal generators 238,358will be taken into account

In this communication a novel beamforming scheme is presented, which is based on regular spatial sampling (RSS) of signals. RSS beamforming allows low-complexity algorithms for smart antennas, while at the same time improving the performance of those systems. An implementation concept is presented, which shows the feasibility of implementing RSS beamforming on today's readily available hardware platforms

Short range communication systems such as Bluetooth and DECT (digital enhanced cordless telecommunications) require low-cost transceiver structures. Hence, the development of appropriate receiver techniques has been a major research topic. Particularly, analog limiter-discriminator with integrate and dump filtering (LDI) techniques have received considerable attention. With the availability of digital signal processing (DSP), the digital implementation of LDI techniques has become increasingly attractive. In order to make LDI receivers more accessible, zero-crossing detection was proposed. In this communication, the authors shall focus on a novel, yet promising, approach to digital zero-crossing detection in the intermediate frequency domain. Zero-crossing demodulation is an irregular sampling technique, which replaces the commonly employed regular, i.e. temporally equidistant sampling technique in the mentioned low-cost receivers. In this manuscript, the authors will present the theoretical aspects of zero-crossing demodulation with special focus on Bluetooth enhanced data rate (EDR). Next, the obtained performance results in terms of the bit error ratio (BER). Comparisons with theoretical bounds show the advantageous performance. Furthermore, a demonstrator concept termed HAWK shall be discussed and first measurement results will be presented

In this communication, the authors present a software defined radio (SDR) transceiver design, termed FALCON. The FALCON is entirely based on a modular signal processing concept. In particular, the receiver deploys modules which process and generate log-likelihood ratio (LLR) signals, hence, providing the capability of a plug-and-play-type reconfigurability. To the best knowledge of the authors, such a reconfigurability approach has not yet been pursued as consequently before. The authors present their reconfigurability approach in this communication. The FALCON currently deploys commercial radio frequency (RF) front-ends provided by Atmel, analog and interface boards developed and implemented by the authors and DSP starter kits (DSK) with TI TMS320C6416 DSPs, provided by Texas Instruments. The hardware/software integration has been done in the laboratory of the authors as well as the development of all the signal processing modules, which have been realized in C language tailored for the TMS320C6416 DSPs (digital signal processors). The authors describe the FALCON and present measurement results. For an easy comparison of these results with widely published simulation results the authors consider UMTS/W-CDMA. It is shown that the FALCON provides superb performance

Short range communication systems such as Bluetooth and DECT (digital enhanced cordless telecommunications) deploy GFSK (Gaussian frequency shift keying) modulation which has been derived from MSK (minimum shift keying). In this communication, the authors discuss and analyze an improved zero-crossing detector for MSK signals, deploying a least squares (LS) approach. The novel detector is termed zero-crossing decorrelation detector (ZXDD). The impact of bandlimitation due to bandpass filtering is taken into account, explicitly.

Bluetooth is a short-range communication system facilitating ad-hoc networking between various devices and terminals, using a digital frequency modulation (FM) scheme termed GFSK (Gaussian frequency shift keying). In this communication, the authors present a novel receiver structure for Bluetooth which is based on zero crossing demodulation in combination with a decorrelating matched filter. Simulation results show performance improvements compared to conventional zero crossing detectors.