Markku J. Juntti

• Dr.Sc.(Tech)
• Professor at University of Oulu

We propose a new power amplifier (PA) behavioral modeling approach, to characterize and compensate for the signal quality degrading effects induced by a PA with a machine learning (ML) aided piece-wise (PW) modeling approach. Instead of using a single pruned Volterra model, we use multiple small-size pruned Volterra models by classifying the input...

We develop a low-complexity algorithm to design the hybrid beamforming matrices in mmWave MIMO-OFDM systems. The proposed scheme is feasible and practical for massive mmWave MIMO systems since all solutions are closed-form. The paper is to appear in the proceedings of VTC2021-Fall.

As fifth generation (5G) research is maturing towards a global standard, the research community has started to focus on the development of beyond-5G solutions and the 2030 era, i.e. 6G. In the future, our society will be increasingly digitised, hyper-connected and globally data driven. Many widely anticipated future services will be critically depe...

We propose a carefully selected receiver structure, detector and detector implementation architecture for multiple-input multiple-output (MIMO) uplink base station receiver for fourth generation (4G) wireless cellular systems. First, we compare different receiver algorithms and structures for single-carrier frequency-division multiple access (SC-FD...

A ray tracing simulator for urban and indoor environments is introduced. The simulator uses NVIDIA graphics processing unit (GPU) accelerated CUDA parallel computing platform and programming mode and the OptiX Ray Tracing Engine. As a use case, channel characteristics for Global Navigation Satellite System (GNSS) satellites are simulated and compar...

Compressed sensing (CS) [Candes, Donoho, Romberg, Tao et al. in 2006] is an effective joint sampling and compression paradigm to reduce energy consumption for acquiring sparse signals in low-power sensor applications. Since quantization is inevitable in practice, we study rate-distortion (RD) performance of various single-sensor CS schemes for acqu...

While the IoT has made significant progress supporting individual machine-type applications, it is only recently that the importance of people as an integral component of the overall IoT infrastructure has started to be fully recognized. Several powerful concepts have emerged to facilitate this vision, whether involving the human context whenever r...

We propose a framed slotted Aloha-based adaptive method for robust communication between autonomous wireless nodes competing to access a channel under unknown network conditions such as adversarial disruptions. With energy as a scarce resource, we show that in order to disrupt communications, our method forces the reactive adversary to incur higher...

Digital predistortion (DPD) is a widely adopted baseband processing technique in current radio transmitters. While DPD can effectively suppress unwanted spurious spectrum emissions stemming from imperfections of analog RF and baseband electronics, it also introduces extra processing complexity and poses challenges on efficient and flexible implemen...

This paper considers a downlink transmission of cloud radio access network (C-RAN) in which precoded baseband signals at a common baseband unit are compressed before being forwarded to radio units (RUs) through limited fronthaul capacity links. We investigate the joint design of precoding, multivariate compression and RU-user selection which maximi...

This paper considers a multicell downlink channel in which multiple base stations (BSs) cooperatively serve users by jointly precoding shared data transported from a central processor over limited-capacity backhaul links. We jointly design the beamformers and BS-user link selection so as to maximize the sum rate subject to user-specific signal-to-i...

Mean interference power and probability of outage in the THz band (0.1 – 10 THz) networks are studied. The frequency band has potential for enabling future short range communication systems because of the large available spectrum resources. This can enable huge data rates, or on the other hand, large numbers of users sharing the resources. The latt...

This paper studies energy-efficient coordinated beamforming in multi-cell multi-user multigroup multicast multiple-input single-output systems. We aim at maximizing the network energy efficiency by taking into account the fact that some of the radio frequency chains can be switched off in order to save power. We consider the antenna specific maximu...

The invention relates to an apparatus including: at least one processor and at least one memory including a computer program code, the at least one memory and the computer program code configured to, with the at least one processor, cause the apparatus at least to: obtain a channel quality indicator comprising a detector class indicator informing t...

The challenges with full-duplex (FD) transceiver implementation and transmission in small area radio communication systems are considered. The main challenge in the FD transceiver design is the self-interference (SI). Analog and digital SI cancellation is used for SI mitigation. Analog SI isolation is performed at radio frequency (RF) by utilizing...

As a wide class of resource management problems in wireless communications are nonconvex and even NP-hard in many cases, finding globally optimal solutions to these problems is of little practical interest. Towards more pragmatic approaches, there is a rich literature on iterative methods aiming at finding a solution satisfying necessary optimality...

This paper proposes energy-efficient coordinated beamforming strategies for multi-cell multi-user multiple-input single-output system. We consider a practical power consumption model, where part of the consumed power depends on the base station or user specific data rates due to coding, decoding and backhaul. This is different from the existing app...

Lossy compressed sensing (CS) of a sparse source is studied. A lower bound to the best achievable compression performance in a finite rate CS setup is established by providing support side information to the encoder and decoder. The rate-distortion problem is formulated via remote source coding and conditional rate-distortion theory. The best encod...

Degrees of freedom (DoF) is studied in the downlink of a heterogenous wireless network modeled as a two-layered interference network. The first layer of the interference network is the backhaul layer between macro base stations (MB) and small cell base stations (SB), which is modeled as a Wyner type linear network. The second layer is the transmiss...

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...

We consider the problem of 3D multiple-input-multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) channel estimation, a key for the future development of 3D beamforming techniques. Our main contribution is a novel algorithm, namely the adaptive-LASSO, that can jointly exploit the sparsity structure of the MIMO-OFDM channel in th...

This paper addresses distributed finite-rate quantized compressed sensing (QCS) acquisition of correlated sparse sources in wireless sensor networks. We propose a distributed variable-rate QCS compression method with complexity-constrained encoding to minimize a weighted sum of the mean square error distortion of the signal reconstruction and the a...

This paper studies energy-efficient coordinated beamforming in multi-cell multi-user multiple-input single-output (MISO) system. On contrary to the existing approaches where the power consumption of a base station is modeled as a convex or linear function, we consider a more practical model where part of the processing power depends on the rate pro...

Coordinated downlink multi-point transmission with joint processing is considered for weighted sum rate maximization with limited backhaul connectivity. The cooperating base stations are assumed to form a network with a tree topology. The limited backhaul capacity is modeled as the maximum number of active users per base station. The combinatorial...

We consider the problem of designing transmit and receive precoders to minimize the number of backlogged packets at the base stations (BSs) in a multiple-input multiple-output (MIMO)-orthogonal frequency division multiplexing (OFDM) scenario. Due to the nonconvex nature of the problem, we propose an iterative method for designing transmit precoders...

Results on penetration loss measurements in the THz frequencies between 0.1-2 THz are reported. The measurements were conducted with time domain spectroscopy using the TeraView TeraPulse 4000 measurement equipment. We concentrate on the frequency-dependent penetration characteristics of various materials typical for indoor environments, providing b...

We consider a downlink multi-cell multiple-input multiple-output (MIMO) interference broadcast channel (IBC) using orthogonal frequency division multiplexing (OFDM) with multiple users contending for space-frequency resources in a given scheduling instant. The problem is to design precoders efficiently to minimize the number of backlogged packets q...

Weighted sum rate maximization (WSRMax) with user specific quality-of-service (QoS) constraints and general convex transmit power constraints is considered in multi-cell multi-user multiple-input multiple-output system. The particular focus in the proposed joint transmitter-receiver design is on tractability in terms of implementation and moderatel...

Measurement results on rough surface scattering on common indoor materials in the terahertz (THz) band from 100 GHz to 4 THz are reported. The measurements were made using THz time domain spectroscopy (THz-TDS)-based measurement device in multiple transmitter and receiver angles for five different materials: aluminium, glass, plastic, hardboard, an...

This paper addresses channel-robust compressed sensing (CS) acquisition of sparse sources under complexity-constrained encoding over noisy channels in wireless sensor networks. We propose a single-sensor joint source-channel coding method based on channel-optimized vector quantization by designing a CS-aware encoder-decoder pair to minimize the end...

The impact of the terrestrial network interference to a satellite uplink transmission is studied in this paper. In a system, where an LTE terrestrial network is extended by a satellite communication, the terrestrial interference can become a problem. The interference levels are studied via infield measurements and link budget calculations and the i...

We present the design exploration and the performance evaluation of a mobile transmitter digital predistortion (DPD) module on a mobile GPU. Digital predistortion is a widely used technique for suppressing the spurious spectrum emission caused by the imperfection of power amplifier and radio frequency (RF) circuits in a real wireless transmitter. C...

Upcoming standards are moving towards multi-antenna multiple-input multiple-output (MIMO) transmission techniques to harness the benefits of spatial degrees of freedom (DoF) in addition to the conventional time and frequency resources. Even though single user MIMO transmission improves the throughput noticeably, multiplexing different user data str...

Recent results have revealed that massive multiple-input-multiple-output (MIMO) channels exhibit a sparse structure. In this paper, we leverage this feature into the development of a novel channel estimation algorithm, namely, the Adaptive-Least Absolute Shrinkage and Selection Operator (A-LASSO), in which the sparsifying matrix (dictionary) and th...

We study energy-efficient decentralized coordinated beam-forming in multi-cell multiuser multiple-input single-output system. The problem of interest is to maximize the weighted sum energy efficiency subject to user-specific quality of service constraints. The original problem is iteratively approximated as a convex program according to successive...

We consider application specific integrated circuit (ASIC) implementation of two detector algorithms for multiple- input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems. Higher data rate and lower power consumption requirements set new challenges for implementation. An optimal detector would be able to change the de...

This paper focuses on molecular absorption noise caused by molecular absorption in the higher frequency bands, such as THz band (0.1-10 THz). This transmission induced noise has been predicted to exist in the THz band, since the conservation of energy requires the conservation of the absorbed energy in the medium. There exist multiple models for th...

Weighted sum rate maximizing beamformer design is considered for MIMO broadcast channel. As opposed to the conventional alternating beamformer design, the transmit and receive beamformers are jointly optimized using successive semidefinite programming. The weighted sum rate maximization is approached via the corresponding mean-squared error minimiz...

3GPP LTE-A offers new technologies such as non-contiguous carrier allocation for improving radio spectrum utilization. However, implementation of these technologies is challenging because of intermodulation distortion caused by non- linearity of components. Digital Predistortion (DPD) offers a way for compensating for these nonlinearities by modify...

This paper studies beamforming techniques for energy efficiency maximization (EEmax) in multiuser multiple-input single-output (MISO) downlink system. For this challenging nonconvex problem, we first derive an optimal solution using branch-and-reduce-and-bound (BRB) approach. We also propose two low-complexity approximate designs. The first one use...

We analyze the energy detection performance under multiple scattering conditions in THz band (0.1--10 THz). The analysis focuses on nanonetworks. Thus, limitations on the devices, such as transmit power, is taken into account. We extend our existing multiple scattering model for normally distributed scattering particle size parameters. The primary...

We consider new Dynamic Network Architecture (DNA) which provides significant soft capacity in the network enabling a wide range of adaptations to traffic demand variations without any change in the fixed network infrastructure. To maximize the system throughput we propose a new second order cone programming (SOCP) based algorithm to optimize joint...

We investigate the fairness of achievable energy efficiency in a multicell multiuser multiple-input single-output (MISO) downlink system, where a beamforming scheme is designed to maximize the minimum energy efficiency among all base stations. The resulting optimization problem is a nonconvex max-min fractional program, which is generally difficult...

The goal of this paper is to provide analytical assessment that justifies the performance tendencies of practical encoding/decoding techniques for a binary data gathering wireless sensor network (WSN). The theoretical rate region of the WSN is approximately analyzed based on the Slepian-Wolf theorem. We also derive the bit error rate (BER) floor gi...

We interpret the device-to-device (D2D) cooperative relaying framework as an instance of a two-node binary chief executive officer (CEO) problem. Noise-corrupted versions of a binary sequence are transmitted by two nodes to a single destination node over orthogonal multiple access channel. A lower bound of the bit error probability (BEP) is obtaine...

We study the problem of energy efficiency maximization (EEmax) with user-specific quality of service constraints in multiple-input single-output broadcast channels with transmit beamforming. For this challenging nonconvex problem, we propose an efficient approximate design based on sequential convex approximation (SCA). By proper reformulations we...

This paper investigates the outage behavior of transmitting correlated binary sources with arbitrary code rate over quasi-static Rayleigh fading multiple access channel (MAC). The sufficient condition for lossless communication with arbitrary code rate is obtained by assuming separate source and channel coding, which indicates the two rate regions...

Frequency domain scattering loss on small particles in terahertz frequency band (0.1–10 THz) is addressed. The wavelengths in THz band are short enough to enable scattering on small particles in the atmosphere. Rayleigh theories are utilized in estimating the scattering loss and it is shown that in proper conditions small particle scattering causes...

This paper investigates resource allocation for multi-homing networks where users can simultaneously transmit data to multiple radio access networks (RANs) using multiple air interfaces. We aim at optimally assigning the bandwidth and power to each user-RAN connection so as to maximize energy-efficiency of the entire network subject to user specifi...

This paper compares the performance of several multiuser detection (MUD) algorithms for TD-CDMA (time division CDMA) uplink. The performance study includes the zero-forcing detector, the LMMSE (linear miminum mean squared error) detector and hard-decision parallel interference cancellation (HD-PIC) detector. Overview of the UTRA TDD mode based on T...

This paper considers sequential compressed acquisition and progressive reconstruction of spatially and temporally correlated sensor data streams in wireless sensor networks (WSNs) via compressed sensing (CS). We develop a sequential framework based on sliding window processing, in which the sink can efficiently reconstruct the current sensors' read...

Channel occupancy rate (COR) is the fraction of the time that a channel is occupied, i.e., contains signal(s) in addition to noise. Estimation of COR is important, e.g., in cognitive radio systems, which can use this information for intelligently adapting their spectrum use to the operating environment. For COR estimation, both the ability to opera...

This paper proposes a semi-analytical performance prediction method for an iterative receiver that processes signals arriving through a frequency selective multiple-input multiple-output radio channel. Earlier results provide a distribution of the signal-to-interference-and-noise ratio at the output of a frequency-domain soft-cancellation minimum m...

We study the joint beamforming and antenna selection problem for energy efficiency maximization in multi-user multiple-input single-output (MISO) downlink channel. By viewing antenna selection as finding a sparse solution, we first introduce a sparsity-inducing regularization term to the design problem. Since the resulting problem is nonconvex, it...

Time and frequency domain channel models are proposed for nanonetworks utilizing the terahertz band (0.1-10 THz) for wireless communication. Nanonetworks are formed by tiny nanodevices which consist of nanoscale (molecular scale) components. Channel models capturing the unique peculiarities of the THz band are needed for designing proper physical l...

One of the promising candidates for mitigating the inter-cell interference in multi-cell networks is coordinated beamforming (CB), where cells are allowed to cooperate such that the transmission from each cell takes into account the interference it would cause to the users of other cells. In this work, we study the performance of a centralized algo...

This paper studies the problem of resource allocation for uplink multi-homing users in heterogeneous network where users can simultaneously transmit data to multiple radio access networks (RANs). The considered design problem is to optimally assign bandwidth and power to each user-RAN connection so as to maximize the overall energy efficiency of th...

In order to meet the requirement of high data rates for the next generation wireless systems, the efficient implementation of receiver algorithms is essential. On the other hand, the rapid development of technology motivates the investigation of programmable implementations. This paper summarizes the design of a programmable turbo decoder as an app...

Lattice reduction (LR) is a preprocessing technique for multiple-input multiple-output (MIMO) symbol detection to achieve better bit error-rate (BER) performance. In this paper, we propose a customized homogeneous multiprocessor for LR. The processor cores are based on transport triggered architecture (TTA). We propose some modification of the popu...

We maximize achievable secrecy rate while performing antenna selection (AS) when we do not have perfect availability of instantaneous channel covariance matrices of the legitimate (L) and eavesdropper/wiretapper (E) nodes. Instead, we have at our disposal corrupted estimates of the channel covariance matrices. The error component of the estimated m...

Broadband wireless channels observed at a receiver cannot fully exhibit dense nature in a low to moderate signal-to-noise ratio (SNR) regime, if the channels follow a typical propagation scenario such as Vehicular-A or Pedestrian-B. It is hence expected that ℓ1-regularized channel estimation methods can improve channel estimation performance in the...

A two-node binary chief executive officer (CEO) problem is investigated. Noise-corrupted versions of a binary sequence are forwarded by two nodes to a single destination node over orthogonal additive white Gaussian noise (AWGN) channels. We first reduce the binary CEO problem to a binary multiterminal source coding problem, of which an outer bound...

The conventional ℓ2 multiburst (MB) channel estimation can achieve the Cramér-Rao bound asymptotically by using the subspace projection. However, the ℓ2 MB technique suffers from the noise enhancement problem if the training sequences (TSs) are not ideally uncorrelated. We clarify that the problem is caused by an inaccurate noise whitening process....

Requirements for higher data rates and lower power consumption set new challenges for hardware implementation of multiple-input multiple-output orthogonal frequency division multiplexing receivers. Simple detectors have the advantage of low complexity and power consumption, but they cannot offer as good performance as more complex detectors. Theref...

This paper proposes a semianalytical performance prediction method for an iterative receiver that processes signals arriving through a frequency-selective multiple-input multiple-output radio channel. Earlier results provide a distribution of the signal-to-interference-plus-noise ratio at the output of a frequency domain soft interference cancellat...

The self-interference (SI) channel in full duplex transceivers is investigated. The SI channel is measured using ultra wide-band antennas. Narrow-band measurement technique is used for the channel measurements so that spatial resolution of 4.3 cm is achieved. Measurements are done in a variety of locations including an anechoic chamber with differe...

The energy efficient bit and power loading problem is studied for the multicarrier communication systems aiming to maximize the system energy efficiency (EE) under the total transmit power constraint, the per subcarrier bit error rate (BER) constraint and the minimum transmission rate constraint. To solve the non-convex combinatorial EE optimizatio...

We consider the single-user multiple-input multiple-output (MIMO) precoder design problem for the doubly spatially correlated partially coherent Rayleigh fading channels with discrete inputs. The objective is to design a linear precoder to adapt to the degradation caused by the imperfect channel estimation at the receiver and the transmit-receive a...

Cognitive radio networks present challenges at many levels of design, including configuration, control, and cross-layer optimization. To meet requirements of bandwidth, flexibility and reconfigurability, systematic methods to model and analyze cognitive radio designs on signal processing platforms are desired. To help address these challenges, we p...

Higher data rate and lower power consumption requirements set new challenges for implementation of multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) receivers. Simple detectors have low complexity and power consumption, but the performance is worse than with more complex detectors. Therefore the detector can be a...

Cognitive radio (CR) systems require flexible and adaptive implementations of signal processing algorithms. An adaptive symbol detector is needed in the baseband receiver chain to achieve the desired flexibility of a CR system. This paper presents a novel design of an adaptive detector as an application-specific instruction-set processor (ASIP). Th...

We address the problem of the downlink beamformer design for signal-to-interference-plus-noise ratio balancing in a multiuser multicell environment with imperfectly estimated channels at base stations. We first present a semidefinite program (SDP)-based approximate solution to the problem. Then, as our main contribution, by exploiting some properti...

Increasing the flexibility in spectrum access is a key to enhanced efficiency in radio spectrum utilization. Non-contiguous carrier aggregation (CA) is one enabling technology towards more flexible spectrum access, but can also lead to serious implementation challenges in terms of transmitter lin-earity. Especially when a single power amplifier (PA...

This paper proposes an extrinsic information transfer (EXIT)-chart based optimization technique of LDPC codes for the transmission of quantized Gauss-Markov (GM) source samples over additive white Gaussian (AWGN) noise channels. A joint source and channel (JSC) decoding technique of the proposed code is also devised. In the proposed scheme, no inte...