Joint multiuser power allocation and iterative multi-antenna receiver design

Abstract This thesis concentrates on joint optimization of transmit power allocation and receive filtering in multiuser, multi-antenna communications. Due to the increasing number of wireless devices, the design of energy-efficient communication links is becoming increasingly important. In cellular mobile communications, reducing the average power consumption in uplink transmission is beneficial for users in order to extend battery life and, hence, energy efficiency in general. However, the power consumption of the high power amplifier (HPA) at the transmitter depends on the peak power of the transmission. This thesis focuses on power allocation problems for single-carrier (SC) frequency division multiple access (FDMA) and orthogonal FDMA (OFDMA) transmission assuming iterative reception. The goal in the first scheme presented in this thesis is to reduce the average power consumption by designing a power allocation method that takes into account the convergence properties of an iterative receiver in multiuser uplink communications. The proposed scheme can guarantee that the desired quality of service (QoS) is achieved after a sufficient number of iterations. Reducing the peak-to-average power ratio (PAPR) in any transmission system is beneficial because it allows the use of inexpensive, energy-efficient power amplifiers. The goal in the second scheme presented in this thesis is to control the PAPR of the transmitted signal. Hence, in addition to the QoS constraint, the instantaneous PAPR constraint is derived for SC-FDMA and OFDMA transmission. Moreover, a statistical approach is considered in which the power variance of the transmitted waveform is controlled. The QoS and PAPR constraints are considered jointly and, therefore, the proposed power allocation strategy jointly takes into account the channel quality and the PAPR characteristics of the power amplifier. However, the PAPR constraint can be adopted to any SC-FDMA or OFDMA framework and it is not restricted to the scheme presented in this thesis. The objective of the optimization problems considered throughout the thesis is to minimize the sum power. The majority of the derived constraints are non-convex and therefore, two alternative successive convex approximations (SCAs) are derived for all the non-convex constraints considered. The numerical results show that the proposed power allocation strategies can significantly reduce the average transmission power of users while allowing flexible PAPR control. Hence, the proposed methods can be used to extend battery life for users and especially improve the QoS at the cell edges.Tiivistelmä Väitöskirjassa tutkitaan lähettimessä tapahtuvan tehoallokoinnin sekä vastaanottimessa tapahtuvan signaalin suodatuksen yhteisoptimointia monikäyttöön suunnatussa langattomassa moniantennikommunikaatiossa. Langattomien laitteiden lukumäärän kasvaessa energiatehokkuuden merkitys tiedonsiirtolinkkien suunnittelussa korostuu. Soluihin perustuvassa langattomassa tietoliikenteessä keskimääräisen tehonkulutuksen pienentäminen ylälinkkilähetyksessä (käyttäjältä tukiasemaan) on tärkeää käyttäjän kannalta, sillä se pidentää laitteen akun kestoa. Lähettimen tehovahvistimen (high power amplifier (HPA)) tehonkulutus on kuitenkin verrannollinen lähetyksen huipputehoon. Väitöskirjassa luodaaan uusia menetelmiä sekä vertaillaan tehoallokointia yhden kantoaallon taajuustason monikäyttöön (single carrier frequency division multiple access (SC-FDMA)) ja ortogonaalisen taajuustason monikäyttöön (orthogonal FDMA (OFDMA)) perustuvissa lähetysteknologioissa. Työn ensimmäisessä osiossa tavoitteena on keskimääräisen tehonkulutuksen pienentäminen monen käyttäjän ylälinkkikommunikaatiossa suunnittelemalla tehoallokointimenetelmä, joka ottaa huomioon iteratiivisen vastaanottimen konvergenssiominaisuudet. Työssä ehdotettu menetelmä takaa vastaanotetun informaation halutun laadun (quality of service (QoS)) riittävän monen vastaanottimessa tehdyn iteraation jälkeen. Huipputehon ja keskitehon suhteen (peak to average power ratio (PAPR)) pienentäminen missä tahansa lähetyksessä on hyödyllistä, sillä sen ansiosta voidaan käyttää energiatehokkaampia ja halvempia tehovahvistimia. Työn jälkimmäisessä osiossa tavoitteena on kontrolloida lähetetyn signaalin huipputehon ja keskitehon suhdetta. Työn ensimmäisessä osiossa esitetyn QoS-rajoitteen lisäksi tehoallokointia rajoitetaan symbolisekvenssikohtaisella PAPR-rajoitteella SCFDMA- ja OFDMA-lähetyksessä. Lisäksi esitetään tilastollinen menetelmä, jossa rajoitetaan lähetetyn signaalin tehon varianssia. Kun käytetään yhtäaikaisesti QoS- ja PAPR-rajoitteita, voidaan tiedonsiirtokanavaan suunnitella optimaalinen tehoallokointi ottaen huomioon tehovahvistimen epälineaarisuudet. Työssä esitetty PAPR-rajoite on kuitenkin geneerinen, ja se voidaan sovittaa mihin tahansa SCFDMA- tai OFDMA- optimointikehykseen. Työssä esitettävien optimointiongelmien tavoitteena on käyttäjien summatehon minimointi. Suurin osa työssä esiintyvistä ongelmista on ei-konvekseja, joten siinä esitetään kaksi vaihtoehtoista peräkkäinen konveksi approksimaatio (successive convex approximation (SCA)) -menetelmää kaikille ei-konvekseille rajoitteille. Numeeriset tulokset osoittavat, että esitetyt tehoallokointimenetelmät pienentävät merkittävästi keskimääräistä tehonkulutusta mahdollistaen lisäksi adaptiivisen PAPR-kontrolloinnin. Väitöskirjassa esitettyjen menetelmien avulla voidaan pidentää mobiilikäyttäjien akun kestoa sekä erityisesti parantaa solun reunakäyttäjien palvelun laatua

Report from technical workshop Final Release:ICT-619555 RESCUE D5.5 Version 1.0

Abstract The international workshop ”Advanced PHY andMAC Layer Design for 5G Mobile Networks and Internet of Things” at the European WIRELESS 2016 in Oulu, Finland, was the second and final workshop of the RESCUE project. This workshop was organized by the EU project ICT-RESCUE and the 5G Innovation Centre (5GIC). In average 30 people followed the half-day workshop consisting of two sessions with in total 9 technical papers. Co-located with this workshop RESCUE presented his first public links-on-the-fly demo setup during the ”5G Demonstration Session” at the European WIRELESS 2016.Executive summary This deliverable is a report on the second RESCUE workshop entitled ”Advanced PHY and MAC layer design for 5G Mobile Networks and Internet of Things” in conjunction with European Wireless (EW) conference, 18–20 May 2016, Oulu Finland. The workshop was jointly organized between the 5G Innovation Centre (5GIC) and RESCUE. In conjunction with this workshop, a demo booth for RESCUE project has been built up, where a toy scenario 1 (TS1) functional setup was demonstrated. The workshop, targets the main PHY and MAC as well as channel modeling and methods of performance evaluation topics researched within and outside the RESCUE project. After the review process 9 papers from the 15 submitted contributions have been selected for a final presentation. The acceptance ratio was 60%

Performance analysis for transmission of correlated sources over non-orthogonal MARCs

Abstract Non-orthogonal transmission is considered as one of the promising approaches to improve the throughput of current and future wireless communication networks. We focus on the transmission of correlated sources over a non-orthogonal multiple access relay channel (MARC), which consists of two sources, one relay, and one destination. For non-orthogonal transmission over such networks, only two time slots are required as compared to three time slots used in the conventional orthogonal MARC. At the relay node, physical-layer network coding technique is employed to decode the bit-wise exclusive OR (XOR) version of the sources’ information sequences rather than decode their original individual information sequences. Subsequently, the relay re-encodes the decoded combined sequence and forwards it to the destination. The destination then exploits this sequence as a helper to recover the sources’ original individual information sequences. We analyze the outage probability of the non-orthogonal MARC based on the theorem of multiple access channel (MAC) with a helper, which combines Slepian-Wolf compression rate region and MAC capacity region. Simulation results are provided to verify the accuracy of the theoretical analysis

Performance analysis of OSTBC transmission in lossy forward MIMO relay networks

Abstract We analyze the outage probability for the orthogonal space-time block code based multiple-input multiple-output (MIMO) relay networks, composed of one source, one relay, and a single destination. The relay forwards the decoded and interleaved information sequence even though the information part may contain error(s), according to the lossy forward strategy. In spatially independent MIMO channels, we find that the diversity order of the relay network can be interpreted and formulated by the well-known max-flow min-cut theorem. Moreover, we extend the analysis to the case of spatially correlated MIMO channels. Approximated explicit expressions for the outage probabilities are obtained in high signal-to-noise ratio regime

Minimum power based relay selection for orthogonal multiple access relay networks

Abstract We analyze the performance of a multi-source multi-helper transmission with lossy forward (LF) relaying. In LF, estimates at the relay are encoded and forwarded to the destination for improving the reliability of the received sequence transmitted from the multiple source nodes. Unlike the conventional decode-and-forward (DF) relaying, LF sends the data even in the case where decoding is not error-free. We extend the results of the channel with multiple sources and a single helper to perform relay selection by utilizing the union of rate regions. A power minimization problem is formulated using the above strategy and solved by exploiting the successive convex approximation (SCA) technique. Numerical results are presented to show that the proposed relay selection method achieves the same performance as the exhaustive search

Final report of detailed optimisation algorithm and performance comparisons:ICT-619555 RESCUE D2.2.2 Version 1.0

Abstract This deliverable provides comprehensive theoretical and simulation results on the proposed power optimization algorithms with four toy scenarios identified in the project. The proposed algorithms mainly assume that the statistical channel knowledge and/or location information are available at each node, which aims to be in line with RESCUE “links-on-the-fly” concept. Specifically, the outage probability based joint power allocation and relay position for lossy-forwarding relaying scheme is firstly investigated in toy scenario one, and then the work is extended to a symbol-level selective transmission scheme. For toy scenario two, compared with our previous work in D2.2.1, the outage probability based power allocation is extended to multi-relay case, meanwhile, the power allocation from rate distortion perspective is also investigated. Furthermore, the outage probability based power allocation for toy scenario three is presented for the first time, and the orthogonal multiple access relay channel based power allocation is also illustrated for the case with more than two sources. Based on the provided results, the proposed algorithms exhibit improved performances by comparing with the conventional schemes, e.g., equal-power allocation.Executive summary Recall the Links-on-the-fly Technology for Robust, Efficient, and Smart Communication in Unpredictable Environments (RESCUE) concept that relays are allowed to decode-and-forward the received frames with specified level of errors, which aims to provide efficient and simple information transfer. In this case, the error propagation effects can be mitigated at destination with modified distributed turbo decoding by taking source-relay link correlation information into account. Alternatively, relays can also predict the positions of decoding errors in a frame and then null out them in order to mitigate the error propagation effects. Both of these strategies have a common assumption that channel feedback from reception node to transmission node is not allowed. Thus, the optimal power allocation cannot be based on the knowledge of instantaneous channel state information (CSI). However, we can still use statistical CSI and/or nodes’ location information obtained through long term observation and training. In this deliverable, a comprehensive review of the proposed power allocation algorithms with statistical channel knowledge and/or nodes’ location information for different identified toy scenarios is presented. Firstly, the joint optimization of power allocation (PA) and relay position (RP) for lossy-forwarding relaying is proposed, where the objective is to minimize the system outage probability of toy scenario one (TS1). With the closed-form expression of the outage probability, we investigate adaptive PA with fixed RP, adaptive RP with fixed PA ratio, and joint optimization of PA and RP under total transmit power constraint. It is found that the proposed three algorithms outperform the equal PA, midpoint RP, and semi-adaptive optimization algorithms, respectively. Moreover, we also consider the optimal PA and RP for a symbol-level selective transmission at relay scheme. In this case, the optimal power allocation is to maximize the average received signal-to-noise (SNR) ratio at destination, where the SNR expression includes the derived probability of correctly predicted/forwarded symbols per frame at relay. It is shown that, within four presented relay locations, relay closed to destination provides the best average SNR performance, and its optimal power allocation happens when the relay is allocated with more power. As investigated in D2.2.1, the power allocation in order to minimize the system outage for two relays based chief executive officer (CEO) problem provides better performance than the ones with equal power allocation. In this deliverable, we extend the work with three or more relays cases and propose a simple, yet effective power allocation scheme based on the Slepian-Wolf theorem. Moreover, we also assess the performance of the proposed power allocation for a practical joint decoding (JD) introduced in literature, and the improved performances in terms of average bit-error-rate (BER) can be observed. In addition, we also investigate the optimal power allocation for the lossy communication networks in toy scenario two (TS2). Specifically, we consider the power allocation from rate distortion perspective in order to achieve optimum distortion under total power constraints. The problem can be formulated as convex optimization framework and solved by using Karush-Kuhn-Tucker conditions. In this deliverable, we introduce the optimal power allocation in toy scenario three (TS3) for the first time. Based on the derived outage upper bound presented in deliverable D1.2.2, we design the power allocation strategy to minimize the outage upper bound subject to the total transmission power constraints. It is shown that the proposed power allocation strategy can be asymptotically optimal at high SNR range. Similar as the ones for TS2, we also assess the performance of the proposed power allocation strategy for a practical JD scheme. An improved performance in terms of frame-error-rate (FER) is also observed. Comparing with the work for toy scenario four (TS4) in D2.2.1, we generalize the power allocation problem of lossy forwarding based multiple access relay channel for two sources, single relay and common destination case to more than two sources case. Here, we propose a heuristic power allocation approach for fading channels with the average SNR of each link. The objective of the problem is to minimize the transmit power subject to rate constants, and the non-convex based power allocation problem can still be solved with successive convex approximation method. Numerical results show that the proposed method provides better performances than the conventional cyclic redundancy check based DF relaying in terms of power assumption and outage probability. To sum up, the above mentioned power allocation algorithms for different toy scenarios are implemented mainly based on statistical channel knowledge and/or nodes’ location information, which can be obtained from long terms observation and training. This is consistent with RESCUE “links-on-the-fly” concept, where the signalling to guarantee reliable transmission for a specific link is not allowed in unpredictable environments

Performance analysis of lossy decode-and-forward for non-orthogonal MARCs

Abstract Non-orthogonal transmission is considered to be one of the promising techniques for improving the throughput of the existing and future wireless communication networks. We concentrate on the transmission of both independent and correlated binary sources over a non-orthogonal multiple access relay channel (MARC), which consists of two sources, one relay, and one destination. The lossy decode-and-forward (DF), developed from the conventional DF, is adopted at the relay. Two time slots are required with non-orthogonal transmission over such network setup, while three time slots are required with the conventional orthogonal transmission. We analyze the outage probability of transmission of independent binary sources over the non-orthogonal MARC based on the theorem of multiple access channel (MAC) with a helper, which combines the Slepian-Wolf rate region and the MAC capacity region. For the performance verification, we implement a practical coding-decoding chain, which is applicable to the transmission of both independent and correlated binary sources. Exclusive-OR based multi-user complete decoding is introduced at the relay node, and iterative joint decoding is utilized at the destination by taking into consideration the estimated intra-link error probability and correlation information between the sources. The practical simulation results are well matched with the theoretical analyses

A tutorial on lossy forwarding cooperative relaying

Abstract Lossy decode-and-forward (DF) relaying, also referred to as lossy forwarding (LF), can significantly enhance the transmission reliability and expand the communication coverage at the cost of a small increase in computational effort compared to its DF counterpart. Furthermore, it can further simplify the operations at the relay nodes by removing the errordetecting operation, e.g., cyclic redundancy check, which is used in the conventional DF systems. Due to these advantages, LF has been intensively investigated with the aim of its applications to various cooperative communication networks with different topologies. This paper offers a comprehensive literature review on the LF relaying strategy and makes comparisons between LF and DF. Five basic exemplifying scenarios are taken into consideration. These are the three-node network, the single-source multi-relay network with direct source-to-destination link, the multiple access relay channel, the two-way relay network, and the general multi-source multi-relay network. The paper includes not only theoretical performance limit analyses, but also performance evaluation by employing low-complexity accumulator aided turbo codes at the sources and relays as well as joint decoding at the destination. As expected, the performance enhancement in terms of outage probability, frame error rate, and E-outage achievable rate by LF over DF is significant, which is demonstrated in all the exemplifying scenarios in the literatures. Hence LF has a great potential to be applied to future 5G wireless communication networks, e.g., device-to-device, vehicle-to-vehicle, and machinetype communications, which are composed of the aforementioned exemplifying scenarios

Theoretical results update of assessment on feasibility, achievability, and limits:ICT-619555 RESCUE D1.2.2 Version 1.0

Abstract Compared to the intermediate deliverable D1.2.1, additional results regarding the achievable rate region and performance limit analyses for different toy scenarios (TSs) have been achieved, which are provided in this deliverable. For TS1, we investigate the impact of the line-of-sight component on outage probability with lossy forwarding strategy. Moreover, an improved selective decode-and-forward scheme with least square based symbol level filtering is proposed in order to improve the bit error rate performance of the relaying system. Regarding TS2, the lower bound of the Hamming distortion in the binary chief executive officer (CEO) problem is derived by minimizing the distortion function subject to the inequalities between the obtained tighter outer bound and the channel capacities. An extension to an arbitrary number of sources in the CEO problem is also studied. TS3 is modeled by Slepian-Wolf coding, and we achieve the upper bound of the outage probability by reducing and relaxing the rate constraints. Regarding TS4, we extend the orthogonal transmission to its non-orthogonal counterpart and analyze the outage probability relying on the theorem of multiple access channel with a helper.Executive summary Compared to the intermediate deliverable D1.2.1, this deliverable presents some additional theoretical results regarding the achievable rate regions and performance limits on the links-on-the-fly concept introduced in “Links-onthe-fly Technology for Robust, Efficient, and Smart Communication in Unpredictable Environments” (RESCUE) project. As in D1.2.1, all the theoretical results are obtained based on the simplified four toy scenarios (TSs), where the relays always forward their decoded information sequence to the destination ignoring whether it contains error or not. The advantages of the links-on-the-fly concept over its baseline schemes have been extensively studied and investigated in D1.2.1. Therefore, in this deliverable we mainly focus on the theoretical results of the links-on-the-fly concept by making some scenario extensions and generalizations. Toy Scenario 1 (TS1) is a typical three-node one-way relay network. The achievable rate region of TS1 was studied in D1.2.1 based on the theorem of source coding with a helper and approximated by the Slepian-Wolf theorem. All the links are supposed to be independent and identically distributed (i.i.d) Rayleigh block fading without considering line-of-sight component. We further extend the wireless channels to i.i.d Rician and Nakagami-m fading and calculate the theoretical outage probability of TS1. In addition, the Kullback-Leibler distance between the Rician and Nakagami-m fading distributions is studied, which in turn provides the guideline for the analysis of diversity and coding gains shown in the theoretical outage probability. A more advanced lossy forwarding1 scheme with least square based symbol level filtering is investigated over TS1, which guarantees better bit error rate (BER) performance compared to the baselines. Toy scenario 2 (TS2) is a single-source multiple-relays and single-destination system without direct link between the source and the destination. As in D1.2.1, we mainly focus on the chief executive officer (CEO) problem, which results from the special case where all the source-to-relay links are lossy. We first reduce the binary CEO problem to a binary multiterminal source coding problem. Then, we derive the tighter outer bound on the rate distortion region for the binary multiterminal source coding problem based on the converse proof of the bound. Furthermore, a lower bound on the Hamming distortion for the CEO problem is obtained by minimizing the distortion function subject to the inequalities between the derived outer bound and the channel capacities. Finally, an extension of the binary CEO problem to an arbitrary number of terminals is investigated. The correctness/accuracy of the derivations is also verified through practical simulations using accumulator (ACC) aided turbo codes. Toy scenario 3 (TS3) is an extension of TS2 with direct link between the source and the destination. In the D1.2.1, the selective DF was intensively investigated. Here, we analyze the upper bound of the outage probability by reducing and relaxing the rate constraints based on Slepian-Wolf theorem. Closed form expression for the outage probability is derived for the high signal to noise ratio (SNR) regime with up to four relays. Comparison between the cases with different number of relays is carried out to show the improved diversity order when the number of relays increases. Toy scenario 4 (TS4) is a multiple access relay channel (MARC) with two sources, single relay and a common destination. The achievable rate region and outage probability was intensively studied in D1.2.1 under the constraint of perfect or imperfect source-to-relay links and orthogonal transmission. We relax the restriction on the assumption of orthogonal transmission and apply the non-orthogonal transmission to MARC. A virtual channel between the source-to-relay links is established for the purpose of simplifying the analysis. The achievable rate region is further obtained by the theorem of multiple access channel with a helper, which determines the outage probability. The outage probability of non-orthogonal MARC is slightly worse than orthogonal MARC, but the time slot consumption for the data transmission between sources and destination is reduced considerably

Final dissemination, standardization and exploitation report:ICT- 619555 RESCUE D5.6 Version 1.0

Abstract This document summaries the information on the dissemination and exploitation activities that have taken place during the RESCUE project. Through the academic dissemination and exploitation activates, RESCUE has (co)-organised and participated at workshops, organised summer school, published research results, engaged in teaching and training of students, participated in EC activities, and setup a project website, twitter account, LinkedIn group and YouTube channel. Among the dissemination and exploitation in standardisation and regulation, RESCUE has provided contributions to ITU-R and 3GPP meeting, and delivered the impact of RESCUE research to industry and economics.Executive summary This document describes the activities for dissemination and exploitation of academic research that has been conducted in the RESCUE project. The project proposes the integrated “links-on-the-fly” concept, which encompasses the key technologies of distributed joint source/channel coding, to achieve successful and robust information transfer through multi-path networks, such as public safety scenario or vehicle-to-vehicle (V2V) scenario, which are constructed from lossy point-to-point links. The research results have been published in many world leading journals, conferences and workshops. The number of publications is 17 journal papers and 51 conference/workshop papers. This report lists the details of where the results of RESCUE project have been published, and where the research has been disseminated. For instance, RESCUE has (co)-organised a workshop with DIWINE in conjunction with ICC 2015, and organised summer school in 2015 in Oulu, Finland. Moreover, RESCUE has engaged in teaching and training of students in the form of lectures, tutorials, and by conducting research work in M.Sc. and Ph.D. courses. In addition, RESCUE has participated in EC activities, set up a project website, Twitter account, LinkedIn group and YouTube channel. These activities were successfully conducted and providing great publicity to the project. Among the dissemination and exploitation in standardisation and regulation, RESCUE has also provided its contributions to ITU-R and 3GPP meeting, and delivered the impact of RESCUE research to industry and economics