Efficient Fast-Convolution-Based Waveform Processing for 5G Physical Layer

This paper investigates the application of fast-convolution (FC) filtering schemes for flexible and effective waveform generation and processing in the fifth generation (5G) systems. FC-based filtering is presented as a generic multimode waveform processing engine while, following the progress of 5G new radio standardization in the Third-Generation Partnership Project, the main focus is on efficient generation and processing of subband-filtered cyclic prefix orthogonal frequency-division multiplexing (CP-OFDM) signals. First, a matrix model for analyzing FC filter processing responses is presented and used for designing optimized multiplexing of filtered groups of CP-OFDM physical resource blocks (PRBs) in a spectrally well-localized manner, i.e., with narrow guardbands. Subband filtering is able to suppress interference leakage between adjacent subbands, thus supporting independent waveform parametrization and different numerologies for different groups of PRBs, as well as asynchronous multiuser operation in uplink. These are central ingredients in the 5G waveform developments, particularly at sub-6-GHz bands. The FC filter optimization criterion is passband error vector magnitude minimization subject to a given subband band-limitation constraint. Optimized designs with different guardband widths, PRB group sizes, and essential design parameters are compared in terms of interference levels and implementation complexity. Finally, extensive coded 5G radio link simulation results are presented to compare the proposed approach with other subband-filtered CP-OFDM schemes and time-domain windowing methods, considering cases with different numerologies or asynchronous transmissions in adjacent subbands. Also the feasibility of using independent transmitter and receiver processing for CP-OFDM spectrum control is demonstrated

Continuous-time low-pass filters for integrated wideband radio receivers

This thesis concentrates on the design and implementation of analog baseband continuous-time low-pass filters for integrated wideband radio receivers. A total of five experimental analog baseband low-pass filter circuits were designed and implemented as a part of five single-chip radio receivers in this work. After the motivation for the research work presented in this thesis has been introduced, an overview of analog baseband filters in radio receivers is given first. In addition, a review of the three receiver architectures and the three wireless applications that are adopted in the experimental work of this thesis is presented. The relationship between the integrator non-idealities and integrator Q-factor, as well as the effect of the integrator Q-factor on the filter frequency response, are thoroughly studied on the basis of a literature review. The theoretical study that is provided is essential for the gm-C filter synthesis with non-ideal lossy integrators that is presented after the introduction of different techniques to realize integrator-based continuous-time low-pass filters. The filter design approach proposed for gm-C filters is original work and one of the main points in this thesis, in addition to the experimental IC implementations. Two evolution versions of fourth-order 10-MHz opamp-RC low-pass filters designed and implemented for two multicarrier WCDMA base-station receivers in a 0.25-µm SiGe BiCMOS technology are presented, along with the experimental results of both the low-pass filters and the corresponding radio receivers. The circuit techniques that were used in the three gm-C filter implementations of this work are described and a common-mode induced even-order distortion in a pseudo-differential filter is analyzed. Two evolution versions of fifth-order 240-MHz gm-C low-pass filters that were designed and implemented for two single-chip WiMedia UWB direct-conversion receivers in a standard 0.13-µm and 65-nm CMOS technology, respectively, are presented, along with the experimental results of both the low-pass filters and the second receiver version. The second UWB filter design was also embedded with an ADC into the baseband of a 60-GHz 65-nm CMOS radio receiver. In addition, a third-order 1-GHz gm-C low-pass filter was designed, rather as a test structure, for the same receiver. The experimental results of the receiver and the third gm-C filter implementation are presented

Digital Pre-distortion for Interference Reduction in Dynamic Spectrum Access Networks

Given the ever increasing reliance of today’s society on ubiquitous wireless access, the paradigm of dynamic spectrum access (DSA) as been proposed and implemented for utilizing the limited wireless spectrum more efficiently. Orthogonal frequency division multiplexing (OFDM) is growing in popularity for adoption into wireless services employing DSA frame- work, due to its high bandwidth efficiency and resiliency to multipath fading. While these advantages have been proven for many wireless applications, including LTE-Advanced and numerous IEEE wireless standards, one potential drawback of OFDM or its non-contiguous variant, NC-OFDM, is that it exhibits high peak-to-average power ratios (PAPR), which can induce in-band and out-of-band (OOB) distortions when the peaks of the waveform enter the compression region of the transmitter power amplifier (PA). Such OOB emissions can interfere with existing neighboring transmissions, and thereby severely deteriorate the reliability of the DSA network. A performance-enhancing digital pre-distortion (DPD) technique compensating for PA and in-phase/quadrature (I/Q) modulator distortions is proposed in this dissertation. Al- though substantial research efforts into designing DPD schemes have already been presented in the open literature, there still exists numerous opportunities to further improve upon the performance of OOB suppression for NC-OFDM transmission in the presence of RF front-end impairments. A set of orthogonal polynomial basis functions is proposed in this dissertation together with a simplified joint DPD structure. A performance analysis is presented to show that the OOB emissions is reduced to approximately 50 dBc with proposed algorithms employed during NC-OFDM transmission. Furthermore, a novel and intuitive DPD solution that can minimize the power regrowth at any pre-specified frequency in the spurious domain is proposed in this dissertation. Conventional DPD methods have been proven to be able to effectively reduce the OOB emissions that fall on top of adjacent channels. However more spectral emissions in more distant frequency ranges are generated by employing such DPD solutions, which are potentially in violation of the spurious emission limit. At the same time, the emissions in adjacent channel must be kept under the OOB limit. To the best of the author’s knowledge, there has not been extensive research conducted on this topic. Mathematical derivation procedures of the proposed algorithm are provided for both memoryless nonlinear model and memory-based nonlinear model. Simulation results show that the proposed method is able to provide a good balance of OOB emissions and emissions in the far out spurious domain, by reducing the spurious emissions by 4-5 dB while maintaining the adjacent channel leakage ratio (ACLR) improvement by at least 10 dB, comparing to the PA output spectrum without any DPD

WIMAX 802.16 PHYSICAL LAYER IMPLEMENTATION AND WIMAX COVERAGE AND PLANNING.

Over the last decade, the impact of wireless communication on the way we live and carry out business has been surpassed only by impact of the internet. But wireless communications is still in its infancy and the next stage of its development will be supplementing or replacing network infrastructure that was traditionally wired. The advent and adoption of the computer and the myriad software packages available for it offered the ability to generate a new wave of communication combining art, pictures, music and words into a targeted multimedia presentation. These presentations are large so that is requires higher bandwidth transmission facilities. Coupling this with the need for mobility, the solution would be wireless data delivery putting in consideration the bandwidth request. WiMAX technology is based on the IEEE 802.16 standard, it was only recently when the first IEEE 802.16 based equipment broadband began to enter the market. The additional spectrum, bandwidth and throughout capabilities of 802.16 will remarkably improve wireless data delivery and should allows even more wireless data service areas to be deployed economically. In this Final Year Project, a study about the IEEE 802.16 standard and mainly concentrate on the 802.16 PHY Layer behaviors was performed. A Simulink based model for the 802.16 PHY Layer was built for simulation and performance evaluation of WiMAX. MATLA

Wavelet-based multi-carrier code division multiple access systems

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Nopeaan konvolutioon perustuva suodatettu OFDM ja ikkunoitu OFDM aaltomuotojen suorituskykyvertailussa 5G fyysiselle kerrokselle

Nykyisten mobiiliverkkojen vaatimukset kasvavat jatkuvasti, mikä johtuu pitkälti uusien mobiililaitteiden ja -palveluiden suosion kasvusta. Lisäksi matkapuhelinverkkoja on alettu käyttämään pääasiallisena internetyhteytenä, sillä nykyteknologialla on mahdollista saavuttaa kiinteään laajakaistayhteyksiin verrattavia käyttäjäkokemuksia useimmissa sovelluksissa. Nykyiset Long Term Evolution (LTE) ja LTE-Advanced ovat neljännen sukupolven (4G) teknologioita, jotka tarjoavat jo hyvin suuria tiedonsiirtonopeuksia. Tulevaisuuden palvelut vaativat kuitenkin uusia ominaisuuksia verkolta ja tämän takia uusia teknlogioita tutkitaan jatkuvasti lisää. Viidennen sukupolven (5G) teknologia pyrkii kasvattamaan tiedonsiirtonopeuksia entisestään. Lisäksi on ennustettu, että tulevaisuuden teknologiat vaativat tukea myös pienille ja viivekriittisille lähetyksille, kuten Internet of Things (IoT) ja Machineto-Machine (M2M) -tyyppisille palveluille. Tämä tarkoittaa, että verkkoon yhdistettyjen laitteiden määrä tulee kasvamaan räjähdysmäisesti. Verkossa ovat jatkossa esimerkiksi älykkäät autot, kodinkoneet, sensorit ja monet muut älykkäät laitteet, mikä vaatii mobiiliverkoilta merkittävästi suurta kapasiteettia ja joustavuutta. Tässä diplomityössä tutkitaan kahden uuden aaltomuodon soveltuvuutta 5G aaltomuodoksi: ikkunoitu CP-OFDM ja nopeaan konvoluutioon perustuva suodatettu CP-OFDM. Referenssinä on käytetty LTE-tyylistä kanavasuodatettua CP-OFDM aaltomuotoa vertaillen alltomuotojen spektraalista tehokkuutta ja vuototehoa. Aaltomuotojen suorituskykyä vertaillaan lopuksi kokonaisen tietoliikennelinkin yli. Tulosten perusteella kanavan käyttötehokkuus kasvaa uusilla aaltomuodoilla niin laaja- kuin kapeakaistalähetyksissä, mahdollistaen suurempia tiedonsiirtonopeuksia samassa kanavassa. Parannusta on havaittavissa erityisesti kapeakaistaisten lähetysten vuototehossa. Tämä sallii taajudessa lähekkäin olevien eri alikantoaaltoväliä, eri mittaisia syklisiä etuliitteitä tai eri aikasynkronisuusvaatimuksia käyytävien signaalien lähettämisen samanaikaisesti, häiritsemättä merkittävästi muita lähetyksiä.The demands for modern wireless cellular networks are increasing constantly due to the introduction of new mobile devices and services. Additionally, mobile networks are being used as a primary Internet connection as the current wireless networks are able to achieve similar user experiences than with wired connections in most applications. Long Term Evolution (LTE) and LTE-Advanced are current 4G technologies already allowing very high peak data rates. However, additional features are needed from network to satisfy traffic demands of the future and suitable technologies are in high interest in nowadays research. The fifth generation (5G) wireless system targets to increase data transmission rates further. In addition, it has been forecast that the traffic trends of the future becomes more delay-critical and small bursts communication has a bigger role. These type of services are e.g. Internet of Things (IoT) and Machine-to-Machine (M2M) communications. These increases dramatically the number of devices connected to Internet, for example smart cars, domestic appliances, sensors and other smart devices, which will require significantly improved capacity and flexibility from the forthcoming mobile communication networks. In this thesis, two waveform candidates for 5G are evaluated and compared: Windowed CP-OFDM and Fast Convolution based Filtered CP-OFDM. LTE-like channel filtered CP-OFDM is used as a reference in spectral efficiency, power leakage and overall link performance comparisons of the waveforms. It will be shown that the spectral utilization is improved with proposed waveforms in broadband and narrowband transmissions, which allows higher data rates inside the same bandwidth. The most significant improvement is observed in narrowband power leakage evaluations. Reduced power leakage allows to transmit several narrowband signals with different subcarrier spacings, cyclic prefix lengths, or different timing accuracy with tight frequency spacing without significant interference levels

Nonlinear Distortion in Wideband Radio Receivers and Analog-to-Digital Converters: Modeling and Digital Suppression

Emerging wireless communications systems aim to flexible and efficient usage of radio spectrum in order to increase data rates. The ultimate goal in this field is a cognitive radio. It employs spectrum sensing in order to locate spatially and temporally vacant spectrum chunks that can be used for communications. In order to achieve that, flexible and reconfigurable transceivers are needed. A software-defined radio can provide these features by having a highly-integrated wideband transceiver with minimum analog components and mostly relying on digital signal processing. This is also desired from size, cost, and power consumption point of view. However, several challenges arise, from which dynamic range is one of the most important. This is especially true on receiver side where several signals can be received simultaneously through a single receiver chain. In extreme cases the weakest signal can be almost 100 dB weaker than the strongest one. Due to the limited dynamic range of the receiver, the strongest signals may cause nonlinear distortion which deteriorates spectrum sensing capabilities and also reception of the weakest signals. The nonlinearities are stemming from the analog receiver components and also from analog-to-digital converters (ADCs). This is a performance bottleneck in many wideband communications and also radar receivers. The dynamic range challenges are already encountered in current devices, such as in wideband multi-operator receiver scenarios in mobile networks, and the challenges will have even more essential role in the future.This thesis focuses on aforementioned receiver scenarios and contributes to modeling and digital suppression of nonlinear distortion. A behavioral model for direct-conversion receiver nonlinearities is derived and it jointly takes into account RF, mixer, and baseband nonlinearities together with I/Q imbalance. The model is then exploited in suppression of receiver nonlinearities. The considered method is based on adaptive digital post-processing and does not require any analog hardware modification. It is able to extract all the necessary information directly from the received waveform in order to suppress the nonlinear distortion caused by the strongest blocker signals inside the reception band.In addition, the nonlinearities of ADCs are considered. Even if the dynamic range of the analog receiver components is not limiting the performance, ADCs may cause considerable amount of nonlinear distortion. It can originate, e.g., from undeliberate variations of quantization levels. Furthermore, the received waveform may exceed the nominal voltage range of the ADC due to signal power variations. This causes unintentional signal clipping which creates severe nonlinear distortion. In this thesis, a Fourier series based model is derived for the signal clipping caused by ADCs. Furthermore, four different methods are considered for suppressing ADC nonlinearities, especially unintentional signal clipping. The methods exploit polynomial modeling, interpolation, or symbol decisions for suppressing the distortion. The common factor is that all the methods are based on digital post-processing and are able to continuously adapt to variations in the received waveform and in the receiver itself. This is a very important aspect in wideband receivers, especially in cognitive radios, when the flexibility and state-of-the-art performance is required

Nopeaan konvolutioon perustuva suodatettu OFDM ja ikkunoitu OFDM aaltomuotojen suorituskykyvertailussa 5G fyysiselle kerrokselle

Nykyisten mobiiliverkkojen vaatimukset kasvavat jatkuvasti, mikä johtuu pitkälti uusien mobiililaitteiden ja -palveluiden suosion kasvusta. Lisäksi matkapuhelinverkkoja on alettu käyttämään pääasiallisena internetyhteytenä, sillä nykyteknologialla on mahdollista saavuttaa kiinteään laajakaistayhteyksiin verrattavia käyttäjäkokemuksia useimmissa sovelluksissa. Nykyiset Long Term Evolution (LTE) ja LTE-Advanced ovat neljännen sukupolven (4G) teknologioita, jotka tarjoavat jo hyvin suuria tiedonsiirtonopeuksia. Tulevaisuuden palvelut vaativat kuitenkin uusia ominaisuuksia verkolta ja tämän takia uusia teknlogioita tutkitaan jatkuvasti lisää. Viidennen sukupolven (5G) teknologia pyrkii kasvattamaan tiedonsiirtonopeuksia entisestään. Lisäksi on ennustettu, että tulevaisuuden teknologiat vaativat tukea myös pienille ja viivekriittisille lähetyksille, kuten Internet of Things (IoT) ja Machineto-Machine (M2M) -tyyppisille palveluille. Tämä tarkoittaa, että verkkoon yhdistettyjen laitteiden määrä tulee kasvamaan räjähdysmäisesti. Verkossa ovat jatkossa esimerkiksi älykkäät autot, kodinkoneet, sensorit ja monet muut älykkäät laitteet, mikä vaatii mobiiliverkoilta merkittävästi suurta kapasiteettia ja joustavuutta. Tässä diplomityössä tutkitaan kahden uuden aaltomuodon soveltuvuutta 5G aaltomuodoksi: ikkunoitu CP-OFDM ja nopeaan konvoluutioon perustuva suodatettu CP-OFDM. Referenssinä on käytetty LTE-tyylistä kanavasuodatettua CP-OFDM aaltomuotoa vertaillen alltomuotojen spektraalista tehokkuutta ja vuototehoa. Aaltomuotojen suorituskykyä vertaillaan lopuksi kokonaisen tietoliikennelinkin yli. Tulosten perusteella kanavan käyttötehokkuus kasvaa uusilla aaltomuodoilla niin laaja- kuin kapeakaistalähetyksissä, mahdollistaen suurempia tiedonsiirtonopeuksia samassa kanavassa. Parannusta on havaittavissa erityisesti kapeakaistaisten lähetysten vuototehossa. Tämä sallii taajudessa lähekkäin olevien eri alikantoaaltoväliä, eri mittaisia syklisiä etuliitteitä tai eri aikasynkronisuusvaatimuksia käyytävien signaalien lähettämisen samanaikaisesti, häiritsemättä merkittävästi muita lähetyksiä.The demands for modern wireless cellular networks are increasing constantly due to the introduction of new mobile devices and services. Additionally, mobile networks are being used as a primary Internet connection as the current wireless networks are able to achieve similar user experiences than with wired connections in most applications. Long Term Evolution (LTE) and LTE-Advanced are current 4G technologies already allowing very high peak data rates. However, additional features are needed from network to satisfy traffic demands of the future and suitable technologies are in high interest in nowadays research. The fifth generation (5G) wireless system targets to increase data transmission rates further. In addition, it has been forecast that the traffic trends of the future becomes more delay-critical and small bursts communication has a bigger role. These type of services are e.g. Internet of Things (IoT) and Machine-to-Machine (M2M) communications. These increases dramatically the number of devices connected to Internet, for example smart cars, domestic appliances, sensors and other smart devices, which will require significantly improved capacity and flexibility from the forthcoming mobile communication networks. In this thesis, two waveform candidates for 5G are evaluated and compared: Windowed CP-OFDM and Fast Convolution based Filtered CP-OFDM. LTE-like channel filtered CP-OFDM is used as a reference in spectral efficiency, power leakage and overall link performance comparisons of the waveforms. It will be shown that the spectral utilization is improved with proposed waveforms in broadband and narrowband transmissions, which allows higher data rates inside the same bandwidth. The most significant improvement is observed in narrowband power leakage evaluations. Reduced power leakage allows to transmit several narrowband signals with different subcarrier spacings, cyclic prefix lengths, or different timing accuracy with tight frequency spacing without significant interference levels

Novel Multicarrier Memory Channel Architecture Using Microwave Interconnects: Alleviating the Memory Wall

abstract: The increase in computing power has simultaneously increased the demand for input/output (I/O) bandwidth. Unfortunately, the speed of I/O and memory interconnects have not kept pace. Thus, processor-based systems are I/O and interconnect limited. The memory aggregated bandwidth is not scaling fast enough to keep up with increasing bandwidth demands. The term "memory wall" has been coined to describe this phenomenon. A new memory bus concept that has the potential to push double data rate (DDR) memory speed to 30 Gbit/s is presented. We propose to map the conventional DDR bus to a microwave link using a multicarrier frequency division multiplexing scheme. The memory bus is formed using a microwave signal carried within a waveguide. We call this approach multicarrier memory channel architecture (MCMCA). In MCMCA, each memory signal is modulated onto an RF carrier using 64-QAM format or higher. The carriers are then routed using substrate integrated waveguide (SIW) interconnects. At the receiver, the memory signals are demodulated and then delivered to SDRAM devices. We pioneered the usage of SIW as memory channel interconnects and demonstrated that it alleviates the memory bandwidth bottleneck. We demonstrated SIW performance superiority over conventional transmission line in immunity to cross-talk and electromagnetic interference. We developed a methodology based on design of experiment (DOE) and response surface method techniques that optimizes the design of SIW interconnects and minimizes its performance fluctuations under material and manufacturing variations. Along with using SIW, we implemented a multicarrier architecture which enabled the aggregated DDR bandwidth to reach 30 Gbit/s. We developed an end-to-end system model in Simulink and demonstrated the MCMCA performance for ultra-high throughput memory channel. Experimental characterization of the new channel shows that by using judicious frequency division multiplexing, as few as one SIW interconnect is sufficient to transmit the 64 DDR bits. Overall aggregated bus data rate achieves 240 GBytes/s data transfer with EVM not exceeding 2.26% and phase error of 1.07 degree or less.Dissertation/ThesisDoctoral Dissertation Electrical Engineering 201