The next generation of 6G networks aims to utilize ultra-wideband spectrum and massive antenna arrays to serve multiple users with both control and data channels at low latency and high efficiency. However, phased arrays at mmWave and mid-bands are fundamentally constrained to a single beam or suffer sharp beamforming loss when split across directions, limiting simultaneous control-data support. In FlexLink, we introduce and prototype a novel delay-phased array architecture that overcomes this limitation by redistributing energy jointly across frequency and space, enabling multiple narrow beams without sacrificing per-beam gain or requiring additional power. We design and prototype FlexLink on a custom 4–7 GHz hardware testbed, demonstrating for the first time that control and data beams can be decoupled in practice, achieving nearly double spectral efficiency compared to conventional phased arrays.

We demonstrate mmSubarray, a novel millimeter-wave sub-band phased array system designed to combat interference and maximize spectrum utilization in mmWave networks. Traditional approaches, such as frequency separation and beam nulling, often lead to spectrum under-utilization or coverage gaps. mmSubarray overcomes these limitations by splitting the spectrum into overlapping and non-overlapping sub-bands, assigning non-overlapping bands to interference-prone directions while using overlapping bands to support other directions. It dynamically allocates sub-bands across multiple beams and employs interference nulling to suppress interference below the noise floor. We built a prototype of mmSubarray using commercially available phased arrays and software-defined radio (SDR). Our experimental results show that the system significantly enhances network efficiency, ensuring robust and reliable communication links without sacrificing spectrum or coverage.

The 5G network promised transformative services across various industries, yet its integration has mostly been limited to existing 4G services like IMS-based multimedia and IoT. This paper identifies two key reasons for this underutilization: first, the stringent, multi-dimensional requirements of next-generation verticals like AR/VR, mobile gaming, and robotics, and the limitations of traditional Quality of Service (QoS) approaches in meeting these needs. We argue for a shift towards Quality of Experience (QoE), which better captures user perception and instantaneous application state. To meet stringent QoE demands and optimize network utilization, we emphasize the importance of application state and context awareness within the network. As a solution, we propose AppNet, a novel framework that integrates application awareness into the networking stack via RAN Intelligent Controllers (RICs) of the Open-RAN platform, enabling dynamic QoS adjustments based on application context. This paper highlights 5G private networks as an ideal testing ground, focusing on multi-user scenarios to deliver optimal real-time interactive services at scale.

With 6.5 billion smartphones in use worldwide, each relying on a battery for key subsystems like display, compute, and cellular connectivity, previous studies on power consumption often used invalidated indirect estimates that failed to isolate specific hardware usage. We address this by utilizing Google's On Device Power Rails Monitor (ODPM) tool for precise power measurements of individual components. Our findings indicate that connectivity (Wi-Fi, 4G/5G) and screen display are the primary power consumers, as shown with the Google Pixel 7A. We also confirmed similar power consumption trends using an energy estimation method on the Samsung S23+. Given the prevalence of smartphones, we discuss the challenges and opportunities for optimizing power usage.

We demonstrate FlexLink, a novel frequency-dependent multi-beamforming system designed to optimize spectral efficiency in millimeter-wave networks. Traditional phased arrays offer limited support for simultaneous control and data signals, leading to inefficiencies. FlexLink addresses this by using a delay-phase antenna array to produce high-gain beams for both control and data, nearly doubling spectral efficiency for data signals. Experiments demonstrate FlexLink's ability to utilize the entire frequency spectrum effectively, by radiating different frequencies corresponding to control and data signals to different directions concurrently.

The rapid expansion of wireless technologies demands effective management of complex RAN for MIMO in 5G systems. Current architectures and RAN Intelligent Controllers (RICs) lack critical real-time data processing and physical layer functionalities, hindering MIMO advancements. We introduce BeamArmor5G, an open-source MIMO App development framework that addresses these gaps with comprehensive PHY layer capabilities, enabling detailed wireless channel measurement streaming from RAN to the controller. BeamArmor5G is implemented with srsRAN to empower open-source community researchers to advance beamforming, localization, and interference management, significantly enhancing network performance and enabling new 5G applications.

The adoption of MIMO technology in wireless networks enhances spectral efficiency and enables novel functionalities such as wireless sensing and localization. These functionalities can be enabled by Open-RAN architecture to provide high computation, memory, and data-driven inference through a RAN Intelligent Controller (RIC). However, existing RICs focus mainly on higher network layers and lack essential PHY layer functionalities for MIMO. We present MIMO-RIC, an open-source RAN intelligent controller tailored for MIMO applications. We enable the streaming of extensive 3D wireless channel measurements across antennas, subcarriers, and time, from RAN to MIMO-RIC to develop various MIMO apps like beamforming and localization. We implemented MIMO-RIC on the srsRAN open-source platform using ZeroMQ messaging system for efficient, low-latency communication. Our over-the-air experiment setup consisting of USRP radios and commercial user equipment demonstrates effective jammer monitoring, nulling, and user localization applications.

This demo showcases the mm-O-RAN testbed, integrating mmWave arrays with USRP and the OpenAirInterface (OAI) 5G stack. Our system integrates the mmWave array with synchronized Time Division Duplex (TDD) switching and fast beamforming capabilities, using GPIO triggers from the OAI stack. As the first full integration of a mmWave testbed with an OAI 5G stack, mm-O-RAN addresses key challenges in design and implementation, providing a versatile platform for research and experimentation for AI and signal processing algorithms to optimize end-end network performance.

Millimeter-wave (mmWave) technology is pivotal for next-generation wireless networks, enabling high-data-rate and low-latency applications such as autonomous vehicles and XR streaming. However, maintaining directional mmWave links in dynamic mobile environments is challenging due to mobility-induced disruptions and blockage. While effective, the current 5G NR beam training methods incur significant overhead and scalability issues in multi-user scenarios. To address this, we introduce CommRad, a sensing-driven solution incorporating a radar sensor at the base station to track mobile users and maintain directional beams even under blockages. While radar provides high-resolution object tracking, it suffers from a fundamental challenge of lack of context, i.e., it cannot discern which objects in the environment represent active users, reflectors, or blockers. To obtain this contextual awareness, CommRad unites wireless sensing capabilities of bi-static radio communication with the mono-static radar sensor, allowing radios to provide initial context to radar sensors. Subsequently, the radar aids in user tracking and sustains mobile links even in obstructed scenarios, resulting in robust and high-throughput directional connections for all mobile users at all times. We evaluate this collaborative radar-radio framework using a 28 GHz mmWave testbed integrated with a radar sensor in various indoor and outdoor scenarios, demonstrating a 2.5x improvement in median throughput and an 8x improvement in 20th percentile throughput compared to a non-collaborative baseline.

Modern mmWave systems have limited scalability due to inflexibility in performing frequency multiplexing. All the frequency components in the signal are beamformed to one direction via pencil beams and cannot be streamed to other user directions. We present a new flexible mmWave system called mmFlexible that enables flexible directional frequency multiplexing, where different frequency components of the mmWave signal are beamformed in multiple arbitrary directions with the same pencil beam. Our system makes two key contributions: (1) We propose a novel mmWave front-end architecture called a delay-phased array that uses a variable delay and variable phase element to create the desired frequency-direction response. (2) We propose a novel algorithm called FSDA (Frequency-space to delay-antenna) to estimate delay and phase values for the real-time operation of the delay-phased array. Through evaluations with mmWave channel traces, we show that mmFlexible provides a 60-150% reduction in worst-case latency compared to baselines1.

Millimeter-wave (mmWave) communications are crucial for unlocking the potential of future communication systems. Phased arrays play a vital role in generating directional beams, mitigating the high path-loss associated with these frequencies. Consequently, implementing beamforming within the radio is necessary to serve users in various directions. Applications such as AR/VR and vehicular communications demand rapid beam direction changes, typically within microseconds, to maintain stable connections when the user is mobile. In this demonstration, we showcase a mmWave setup capable of switching beams at microsecond intervals, along with a compact and portable user equipment setup for conducting experiments with high user mobility.

FMCW radars are integral to automotive driving for robust and weather-resistant sensing of surrounding objects. However, these radars are vulnerable to spoofing attacks that can cause sensor malfunction and potentially lead to accidents. Previous attempts at spoofing FMCW radars using an attacker device have not been very effective due to the need for synchronization between the attacker and the victim. We present a novel spoofing mechanism called mmSpoof that does not require synchronization and is resilient to various security features and countermeasures of the victim radar. Our spoofing mechanism uses a "reflect array" based attacker device that reflects the radar signal with appropriate modulation to spoof the victim’s radar. We provide insights and mechanisms to flexibly spoof any distance and velocity on the victim’s radar using a unique frequency shift at the mmSpoof’s reflect array. We design a novel algorithm to estimate this frequency shift without assuming prior information about the victim’s radar. We show the effectiveness of our spoofing using a compact and mobile setup with commercial-off-the-shelf components in realistic automotive driving scenarios with commercial radars.

Millimeter-wave communication with high throughput and high reliability is poised to be a gamechanger for V2X and VR applications. However, mmWave links are notorious for low reliability since they suffer from frequent outages due to blockage and user mobility. We build mmReliable, a reliable mmWave system that implements multi-beamforming and user tracking to handle environmental vulnerabilities. It creates constructive multi-beam patterns and optimizes their angle, phase, and amplitude to maximize the signal strength at the receiver. Multi-beam links are reliable since they are resilient to occasional blockages of few constituent beams compared to a single-beam system. We implement mmReliable on a 28 GHz testbed with 400 MHz bandwidth, and a 64 element phased array supporting 5G NR waveforms. Rigorous indoor and outdoor experiments demonstrate that mmReliable achieves close to 100\% reliability providing 2.3x improvement in the throughput-reliability product than single-beam systems.

Millimeter wave communication systems can provide high data rates, but the system performance may degrade significantly due to interruptions by mobile blockers, such as humans or vehicles. High-frequency interruptions and lengthy blockage durations will degrade the quality of the user's experience. A promising solution is to employ the macrodiversity of base stations (BSs), where the user equipment (UE) can handover to other available BSs if the current serving BS gets blocked. However, an analytical model to evaluate the system performance of dynamic blockage events in this setting is unknown. In this paper, we develop a line-of-sight (LOS) dynamic blockage model and evaluate the probability, duration, and frequency of blockage events considering all the links to the UE which are not blocked by buildings or the user's own body. For a dense urban area, we also analyze the impact of non-LOS links on blockage events. Our results indicate that the minimum density of the BS required to satisfy the quality of service requirements of ultra-reliable low-latency communication applications will be driven mainly by blockage and latency constraints, rather than coverage or capacity requirements.

Current VR headsets are tethered to computers which limits mobility and poses a tripping hazard. Delivering VR content over a wireless link is challenging due to the high data rates and stringent time delivery requirements. Millimeter wave communication at 60 GHz (WiGig) can meet these requirements, but, it is unreliable due to blockages and beam misalignments. In this poster, we present an idea of using both WiFi and WiGig interfaces to transmit the VR content. We divide a video frame into tiles and prioritize the tiles in the user's field of view. Based on the wireless link conditions, the tiles are encoded with varying qualities and transmitted over either WiFi or WiGig interface. We formulate an optimization framework to deliver the VR video with high reliability and low latency.