With video streaming now accounting for the majority of internet traffic, wireless networks face increasing demands, especially in densely populated areas where limited spectral resources are shared among many devices. While multi-user (MU)-MIMO technology aims to improve spectral efficiency by enabling concurrent transmissions over the same frequency and time resources, traditional linear processing methods fall short of fully utilizing available channel capacity. These methods require a substantial number of antennas and RF chains, to support a much smaller number of MIMO streams, leading to increased power consumption and operational costs, even when the supported streams are of low rate. In this demo, we present NL-COMM, an advanced non-linear MIMO processing framework, demonstrated for the first time with commercial off-the-shelf (COTS) user equipment (UEs) in a fully 3GPP-compliant environment. In addition, also for the first time, the audience will compare and assess the quality of live, over-the-air video transmission from four concurrently transmitting UE devices, alternating between current state-of-the-art MIMO detection algorithms and NL-COMM. Key gains of NL-COMM include improved stream quality, halving the number of required base station antennas without compromising stream quality compared to linear approaches, as well as achieving antenna overloading factors of 400%.

Open Radio Access Networks (Open-RAN) trigger a shift from conventional monolithic RAN architectures to disaggregated designs with open interfaces, diversifying the 5G supply chain and boosting innovation. It is envisaged that Open-RAN deployments will be heavily software-based, allowing for higher flexibility and faster integration of new features. However, existing software-based solutions, seem to be unable to realize practical and standard-compliant Multiple-Input, Multiple-Output (MIMO) designs with a large number of concurrently transmitted information streams, as the 5G New Radio standard requires in order to substantially improve connectivity and throughput. In this context, we introduce MIMO-SoftiPHY, the first 3GPP and Open-RAN compliant, software-based physical layer (PHY) design and implementation framework that can practically realize MIMO designs with large numbers of information streams in a power-efficient manner. MIMO-SoftiPHY is inherently integrated with OpenAirInterface, enabling practical, software-based MIMO deployments with commercial-off-the-shelf user equipment. Specifically, MIMO-SoftiPHY achieves real-time performance for 12 MU-MIMO streams at a 10 MHz bandwidth and 8 streams at a 20 MHz. In addition, and in contrast to existing designs, MIMO-SoftiPHY can also support non-linear base-station processing in real-time that, as we show, can result in substantial power savings at the radio side, by obviating the need for a “massive” number of base-station antennas.

Multi-user multiple-input, multiple-output (MU-MIMO) designs can substantially increase the achievable throughput and connectivity capabilities of wireless systems. However, existing MU-MIMO deployments typically employ linear processing that, despite its practical benefits, can leave capacity and connectivity gains unexploited. On the other hand, traditional non-linear processing solutions (e.g., sphere decoders) promise improved throughput and connectivity capabilities, but can be impractical in terms of processing complexity and latency, and with questionable practical benefits that have not been validated in actual system realizations. At the same time, emerging new Open Radio Access Network (Open-RAN) designs call for physical layer (PHY) processing solutions that are also practical in terms of realization, even when implemented purely on software. This work demonstrates the gains that our highly efficient, massively parallelizable, non-linear processing (MPNL) framework can provide, both in the uplink and downlink, when running in real-time and over-the-air, using our new 5G-New Radio (5G-NR) and Open-RAN compliant, software-based PHY. We showcase that our MPNL framework can provide substantial throughput and connectivity gains, compared to traditional, linear approaches, including increased throughput, the ability to halve the number of base-station antennas without any performance loss compared to linear approaches, as well as the ability to support a much larger number of users than base-station antennas, without the need for any traditional Non-Orthogonal Multiple Access (NOMA) techniques, and with overloading factors that can be up to 300%.

This paper presents a DSP acceleration and assessment framework targeting SDR platforms on x86_64 architectures. Driven by the potential of rapid prototyping and evaluation of breakthrough concepts that these platforms provide, our work builds upon the well-known OpenAirInterface codebase, extending it for advanced, previously unsupported modes towards large and massive MIMO such as non-codebook-based multi-user transmissions. We then develop an acceleration/profiling framework, through which we present finegrained execution results for DSP operations. Incorporating the latest SIMD instructions, our acceleration framework achieves a unitary speedup of up to 10×. Integrated into OpenAirInterface, it accelerates computationally expensive MIMO operations by up to 88% across tested modes. Besides resulting in a useful tool for the community, this work provides insight on runtime DSP complexity and the potential of modern x86_64 systems.

It is well documented that the achievable throughput of MIMO systems that employ linear beamforming can significantly degrade when the number of concurrently transmitted information streams approaches the number of base-station antennas. To increase the number of the supported streams, and therefore, to increase the achievable net throughput, non-linear beamforming techniques have been proposed. These beamforming approaches are typically evaluated via simulations or via simplified over-the-air experiments that are sufficient for validating their basic principles, but they neither provide insights about potential practical challenges when trying to adopt such approaches in a standards-compliant framework, nor they provide any indication about the achievable performance when they are part of a standards-compliant protocol stack. In this work, for first time, we evaluate non-linear beamforming in a 3GPP standards-compliant framework, using our recently-proposed SWORD research platform. SWORD is a flexible, open for research, software-driven platform that enables the rapid evaluation of advanced algorithms without extensive hardware optimizations that can prevent promising algorithms from being evaluated in a standards-compliant stack. We show that in an indoor environment, vector perturbation-based non-linear beamforming can provide up to 46% throughput gains compared to linear approaches for 4×4 MIMO systems, while it can still provide gains of nearly 10% even if the number of base-station antennas is doubled.

The concept of Ultra Dense Networks (UDNs) is often seen as a key enabler of the next generation mobile networks. The massive number of BSs in UDNs represents a challenge in deployment, and there is a need to understand the performance behaviour and benefit of a network when BS locations are carefully selected. This can be of particular importance to the network operators who deploy their networks in large indoor open spaces such as exhibition halls, airports or train stations where locations of BSs often follow a regular pattern. In this paper we study performance of UDNs in downlink for regular network produced by careful BS site selection and compare to the irregular network with random BS placement. We first develop an analytical model to describe the performance of regular networks showing many similar performance behaviour to that of the irregular network widely studied in the literature. We also show the potential performance gain resulting from proper site selection. Our analysis further shows an interesting finding that even for over-densified regular networks, a non-negligible system performance could be achieved.

Coping with the extreme growth of the number of users is one of the main challenges for the future IEEE 802.11 networks. The high interference level, along with the conventional standardized carrier sensing approaches, will degrade the network performance. To tackle these challenges, the Dynamic Sensitivity Control (DSC) and the BSS Color scheme are considered in IEEE 802.11ax and IEEE 802.11ah, respectively. The main purpose of these schemes is to enhance the network throughput and improve the spectrum efficiency in dense networks. In this paper, we evaluate the DSC and the BSS Color scheme along with the PARTIAL-AID (PAID) feature introduced in IEEE 802.11ac, in terms of throughput and fairness. We also, exploit the performance when the aforementioned techniques are combined. The simulations show a significant gain in total throughput when these techniques are applied.

In this paper we study the delay characteristics of cooperative communications using opportunistic relay access with delay constraints. We consider the scenario where the source node opportunistically tries to access the relay, amongst several Primary Users (PU) of the relay network in the environment, in order to send data across (a fixed) network to its destination. The first-hop connection for the source node to the relay is considered as an opportunistic access link. The traffic from the PUs in the first-hop and the delay associated in getting the data across the network to the destination from the relay node are modeled as random processes. Considering such a link and a random network-delay model we study the probability of successful end-to-end transmission by the source node with a given delay constraint. For the considered model, we present closed form analytical expressions for the success probability, the mean delay and the expected delay jitter for the end-to-end transmission. We also present Monte-Carlo based simulation results to verify our theoretical analysis.