Escalating mobile service demands require Mobile Network Operators (MNOs) to optimize Radio Access Network (RAN) infrastructure for cost, efficiency, and scalability. While Cloud RAN virtualization improves resource pooling, hardware remains underutilized during low-traffic periods. This study introduces a dynamic resource management framework for 5G Cloud RAN that optimizes L1-Hi processing on hardware accelerators like GPUs and SmartNICs. By combining predictive workload modeling with adaptive allocation, the framework scales resources based on real-time traffic. This approach mitigates over-provisioning, thereby increasing hardware utilization, lowering energy consumption, and reducing operational costs. Simulations confirm the framework enhances hardware efficiency while maintaining user Quality of Experience (QoE), enabling more scalable, costeffective, and sustainable telecom networks.

We propose reliability and latency quantities as metrics to be used in the routing tree optimization procedure for Wi-Fi mesh networks. In contrast to state-of-the-art routing optimization methods, our proposal involves directly optimizing the data rates of individual mesh links according to underlying channel conditions such that reliability and latency requirements are satisfied for entire mesh paths. Moreover, to mitigate the channel contention problem that is common in Wi-Fi networks, we propose a multichannel (MC) assignment method. In this method, bandwidth is allocated to the individual mesh nodes based on the expected traffic load that they are expected to handle. Once the bandwidth for each node is determined, specific channels are assigned in a way to avoid co-channel interference. Furthermore, considerable efforts were spent for developing a system-level simulator that captures the features of the physical (PHY) layer and medium access layer defined in the IEEE 802.11 standard (Wi-Fi). Using this simulator, we were able to show that Wi-Fi mesh networks using the proposed routing metric based on reliability and latency quantities significantly outperform the state of the art. Finally, the mitigation of channel contention through the proposed MC assignment method results in further dramatic gains in performance.

We study terrestrial wireless uplink Time of Arrival (ToA) localization systems where multiple infrastructure nodes measure the ToA from the signal transmitted by a user of interest. The measured ToA is shared with a centralized server that then computes the location of the device. While the fundamental issues such as accurate synchronization and accurate location of nodes concerning precise location estimation have been addressed elsewhere, we mainly focus on improving the efficiency of ToA estimation in this work. Using our proposed methodology, a 30 fold improvement in the computational efficiency at no cost of localization accuracy was observed which in practice enables the localization network to track and coordinate many more simultaneous users frequently. We validated our ToA estimates on the over-the-air measurements taken from our on-campus localization network and obtained sub-meter accuracy, indicating that our solution is competitive with conventional high overhead ToA methods.

Significant uplink capacity improvements for the fifth generation (5G) wireless networks can be achieved by assigning the same time-frequency resources to several users simultaneously. Especially in the case of massive Machine-Type Communications (mMTC) for emerging Internet-of-Things (IoT) applications, where a very large number of devices must be provided with connectivity, the re-utilization of radio resources by concurrent transmissions from several devices is imperative for achieving economic viability. In this context, advanced signal processing in the evolved NodeB (eNB), namely multi-user detection (MUD), is a key enabler to reduce the mutual interference between users and appropriately decode the superposed signals. Turbo-SIC is a very efficient MUD scheme that applies successive interference cancellation (SIC), based on soft outputs of a turbo decoder. In this paper we introduce the implementation of an uplink Turbo-SIC receiver that follows the basic specifications of Long Term Evolution (LTE) systems. Using an LTE compliant open-source software defined radio (SDR) platform, named OpenAirInterface (OAI), we are able to show that Turbo-SIC offers several dBs of advantage over conventional receivers while its basic real-time processing requirements fit the capabilities of present general purpose processors.

Emerging new applications, such as Internet of Things (IoT), gigabit wireless connectivity, tactile internet, and many more are expected to impose new and diverse requirements on the design of the fifth generation (5G) of cellular communication systems. In recent years, many alternative multicarrier waveforms are being investigated with the aim to identify to what extent it would be possible to better address these diverse requirements compared to Cyclic Prefix (CP) OFDM, which is currently adopted by LTE/LTE-Advanced. However, most of these investigations considered in many research activities have focused on theoretical considerations or simulations and mainly with emphasis on only one alternative waveform. In this paper, we present ongoing work based on measurement results where real hardware experiments are conducted to investigate the performance of three waveform families: CP-OFDM, filter bank multicarrier with offset quadrature amplitude modulation (FBMC/OQAM) and universal-filtered OFDM (UF-OFDM). FBMC/OQAM has the benefit of very low sidelobes leading to less inter-carrier interference in asynchronous and high mobility scenarios, whereas the typically long filter leads to low efficiency for short blocks and the use of OQAM makes it nontrivial to adopt certain schemes well-developed for CP-OFDM. UF-OFDM combines the benefits of CP-OFDM with the advantage of significantly lower out-of-band radiation while avoiding the drawbacks of FBMC/OQAM. In this paper we compare the performance of these alternative waveforms under several 5G targeted scenarios.

In current wireless base station solutions it is becoming common to physically separate baseband units and radio subsystems. In many wireless technologies this architecture requires allocation of significant transport network resources. In this paper a low-latency baseband signal compression scheme is presented. The compression scheme significantly lowers the transport data rate while maintaining low levels of signal distortion, thus resulting in a lower-cost transport network. Considering the importance of packet-based networks, a number of additional novel compression schemes are proposed. They are optimized for transport networks that implement a quality-of-service (QoS) mechanism and/or multi-link transmission. The compression schemes are parameterized such that a smooth trade-off between the required signal quality and compression performance can be achieved through operator choice of the suitable parameter values. An attractive feature of these schemes is that they can be applied to different wireless technologies, with appropriate parameter settings, without disrupting the present architecture. The proposed solutions will lead to a cost-effective implementation of collocated and distributed network-centric baseband processing, coordinated multi-point (CoMP) and/or distributed antenna system (DAS) which are critical topics for the entire wireless telecommunications industry and infrastructure.

In this paper we present a multiuser MIMO experimental system and the corresponding indoor measurement results that demonstrate power of distributed and coherently-coordinated downlink transmit antennas using zero-forcing (ZF) beamforming. We present experimental performance under different conditions and communication scenarios. We consider different transmit power levels, number of transmit antennas, resolution of channel state information (CSI) quantizer as well as CSI feedback channel data rates. We demonstrate significant gains even in the presence of practical impairments.

In this paper we study the effects of practical pilot- assisted channel state estimation on the achievable information theoretic data rates (uplink and downlink) in a multiple antenna multiuser TDD system. Specifically, we consider a wireless system with multiple antennas at the base station and a number of mobile terminals each with a single antenna. We analyze the performance of uplink multiuser detection and downlink transmitter optimization that are based on linear spatial filtering. Using a discrete version of the continuously time-varying wireless channel we analyze how a lower bound on the achievable data rates depends on (1) the arrangement of pilot symbols (preamble or postamble); (2) the duration of the uplink and downlink transmissions; and (3) the percentage power allocated to the pilot. Furthermore, we also present the effects of the terminal speeds on the achievable data rates, thereby providing prescriptions for the practical design of the pilot. Specifically, our results point to an uplink postamble with flexible percentage (about 20 - 25 %) pilot power allocation, and transmission durations tailored for specific ranges of terminal speeds.

The wireless communication channel between vehicular nodes in an ad-hoc network was assessed in a comprehensive measurement and modeling effort. Nodes were equipped with roof mounted azimuthally omnidirectional antennas, and measurements were taken at both short (line-of-sight) and long ranges, at a center frequency of 2.5 GHz. The median MIMO capacity with 8 transmitters and 10 receivers (8 times10) was found to be about five times the corresponding 1times1 SISO capacity, and three times the corresponding 1times10 SIMO capacity. Wideband soundings of such channels were conducted, where the median rms delay spread was found to be 0.6 mus. Measurements, spatial correlation scales, an empirical model of pathloss, and cross- polarization properties of peer-to-peer channels in a rural area are reported.

We propose a channel state information (CSI) feedback scheme based on unquantized and uncoded (UQ-UC) transmission. We consider a system where a mobile terminal obtains the downlink CSI and feeds it back to the base station using an uplink feedback channel. If the downlink channel is an independent Rayleigh fading channel, then the CSI may be viewed as an output of a complex independent identically distributed Gaussian source. Further, if the uplink feedback channel is an additive white Gaussian noise channel, and the downlink CSI is perfectly known at the mobile terminal, it can be shown that UQ-UC CSI transmission (that incurs zero delay) is optimal in that it achieves the same minimum mean-squared error distortion as a scheme that optimally (in the Shannon sense) quantizes and encodes the CSI, while theoretically incurring infinite delay. Since the UQ-UC transmission is suboptimal on correlated wireless channels, we propose a simple linear CSI feedback receiver that can be used to improve the performance of UQ-UC transmission while still retaining the attractive zero-delay feature. We provide bounds on the performance of such UQ-UC CSI feedback and study its impact on the achievable information rates. Furthermore, we explore its application and performance in multiple-antenna multiuser wireless systems, and also propose a corresponding pilot-assisted channel-state estimation scheme

We propose a channel state information (CSI) feedback scheme based on unquantized and uncoded (UQ-UC) transmission. We consider a system where a mobile terminal obtains the downlink CSI and feeds it back to the base station using an uplink feedback channel. If the downlink channel is an independent Rayleigh fading channel, then the CSI may be viewed as an output of a complex independent identically distributed Gaussian source. Further, if the uplink feedback channel is AWGN, it can be shown that that UQ-UC CSI transmission (that incurs zero delay) is optimal in that it achieves the same MMSE distortion as a scheme that optimally (in the Shannon sense) quantizes and encodes the CSI while theoretically incurring infinite delay. Since the UQ-UC transmission is suboptimal on correlated wireless channels, we propose a simple linear CSI feedback receiver that can be used to improve the performance while still retaining the attractive zero-delay feature. We provide bounds on the performance of the UQ-UC CSI feedback. Furthermore, we explore its application and performance in multiple antenna multiuser wireless systems.

In single-user MIMO communication, the first-order throughput scaling is determined by the smaller of the number of transmit and receive antennas. This typically renders terminals the constraining bottleneck. In a multiuser downlink, this bottleneck can be bypassed by having the base station communicate with multiple terminals simultaneously, whereby the receive antennas at those terminals are effectively pooled in term of throughput scaling. This, however, requires that the base has instantaneous channel information. Without such information, the structure and statistics of the channel can be exploited to form multiple simultaneous beams towards the various users, but these beams are in general mutually interfering. Focusing on UMTS HSDPA (high-speed downlink packet access), the paper proposes the use of multiuser detection to discriminate the signals conveyed over interfering beams. This approach is formulated and experimentally evaluated on an HSDPA MIMO testbed that involves a commercial base station, multi-antenna terminals, and custom ASICs.

In this paper, a multiple-input-multiple-output (MIMO) extension for a third-generation (3G) wireless system is described. The integration of MIMO concepts within the existing UMTS standard and the associated space-time RAKE receiver are explained. An analysis is followed by a description of an actual experimental MIMO transmitter and receiver architecture, both realized on digital signal processors (DSPs) and FPGAs within a precommercial OneBTS base station. It uses four transmit and four receive antennas to achieve downlink data rates up to 1 Mb/s per user with a spreading factor of 32 and the UMTS chip rate of 3.84 MHz. Furthermore, different MIMO detectors are evaluated, comparing their performance and complexity. System performance is evaluated through simulations and indoor over-the-air measurements. Capacity and bit-error rate measurement results are presented.

We propose a blind successive interference cancellation receiver for asynchronous direct-sequence code-division multiple-access (DS-CDMA) systems using a maximum mean energy (MME) optimization criterion. The covariance matrix of the received vector is used in conjunction with the MME criterion to realize a blind successive interference canceler that is referred to as the BIC-MME receiver. The receiver executes interference cancellation in a successive manner, starting with the most dominant interference component and successively cancelling the weaker ones. The receiver is compared against various centralized and decentralized receivers, and it is shown to perform well in the presence of estimation errors of the covariance matrix, making it suitable for application in time-varying channels. We also analyze properties of the covariance matrix estimates which are relevant to the performance of the BIC-MME receiver. Further, the BIC-MME receiver is particularly efficient in the presence of a few strong interferers as may be the case in the downlink of DS-CDMA systems where intracell user transmissions are orthogonal. An iterative implementation that results in reduced complexity is also studied.

We demonstrate an experimental evaluation of unsupervised (i.e., blind) channel deconvolution that is based on the multi-user kurtosis (MUK) maximization criterion. We focus on the narrowband case and compare the performance of the MUK algorithm against the conventional trained linear MMSE and the V-BLAST algorithm. These results constitute, to the best of our knowledge, the first over-the-air demonstration of blind techniques for multiple-transmitter/multiple-receiver systems.

A multiple antenna system has been shown to provide high capacity wireless communications. We have built a narrowband wireless BLAST testbed with multiple transmit and receive antennas. To validate the effectiveness of the testbed and BLAST technique, we transmit H.263 video at a rate of 230 kbps. The video performance under different channel conditions and error handling options are discussed.

We evaluate the performance of the VBLAST (vertical Bell Labs layered space-time) receiver algorithm in multiple-transmitter/multiple-receiver (MTMR) cellular W-CDMA systems. We assume that the VBLAST algorithm is executed on a symbol level (i.e., on the despread received signal), following a conventional bank of matched filters (correlators). Also, we introduce the concept of virtual antennas. Performance of the algorithm in the presence of intra- and inter-cell multiple-access interference (MAI) is evaluated. System capacity is also studied. The observed system is defined based on the UMTS physical layer and corresponding channel models.

BLAST has been shown to provide high capacity wireless communications by using multiple antennas at both transmitter and receiver. We have built a narrowband wireless BLAST testbed with multiple transmit and receive antennas. We examine the performance of the VBLAST by choosing the antenna configurations and performing link adaptation. It is shown that adapting the number of transmit antennas achieves remarkable performance improvement. To further demonstrate the effectiveness of the testbed, we use over-the-air error traces to simulate H.263+ video transmission.