Power consumption, and the resulting limitation to computational load, is a first-order constraint in designing comfortable all-day-wear extended reality (XR) devices that can provide rich immersive experiences. This paper concerns reducing XR device power consumption by offloading head tracking, one of the top CPU and power consumers, to a remote server. We present RemoteVIO, the first open-source end-to-end XR system that offloads head tracking (visual inertial odometry or VIO) to a remote server. Our work distinguishes itself from past studies on computation offloading in XR by properly addressing two under-explored but critical aspects: 1) a comprehensive evaluation of user experience in a complete end-to-end XR system and 2) a quantification of the net power savings on real hardware.

Emerging applications in the wireless domain such as factory automation or extended reality require high reliable and deterministic communications. New scheduling mechanisms introduced in current state-of-the-art Wi-Fi (i.e. 802.11ax, 802.11be) offer better performance, but in many cases not sufficient to meet the requirements of the aforementioned applications. In this paper, we present a hardware implementation of Scheduled Time-Sensitive Transmission Opportunity (S-TXOP) over Wi-Fi, S-TXOP provides accurate time synchronization and time-aware scheduling to enable highly efficient deterministic wireless communications. We describe a field-programmable gate array software-defined radio S-TXOP implementation, and show numerical and experimental results supporting low cycle time transmissions with determinism.

Managing Wireless networks, particularly in industrial and factory environments, to meet the escalating demands of time critical applications has become more complex and warrants proactive management strategies. This work introduces an innovative approach to wireless network management enabled by a Digital Twin (DT) designed and continuously enhanced by real-time device telemetry and user inputs through an Extended Reality interface. By collecting real telemetry data from network devices, our methodology defines and calibrates a DT representation of the network, enabling accurate prediction of wireless signal properties and network performance based on simulation models. The DT serves as an automation tool to analyze various scenarios, allowing for informed adjustments to user applications, devices and network configurations. The paper describes a real-life DT implementation of a wireless system in a real enterprise network scenario. Experimental results are provided demonstrating improved performance and user experience enabled by the proposed DT-based network management. The proposed methodology addresses the challenges of real-time network optimization and contributes to advance wireless network management based on device and network telemetry.

Mobile and autonomous robots are among the most critical technology applications requiring wireless connectivity with deterministic performance, including bounded latency with high reliability, even under congested network conditions. Emerging Wireless Time-Sensitive Networking (WTSN) capabilities over Wi-Fi and 5G can enable time synchronization and bounded low latency through time-aware scheduling mechanisms. Such Wireless TSN capabilities have been demonstrated in several industrial/robotic use cases, but under static conditions. Mobility introduces new challenges due to the roaming events and associated network outages owing to signaling between client devices and network infrastructure during these events. In this paper, we show how we can take advantage of the TSN redundancy capability (as defined in the IEEE 802.1CB standard) to eliminate outages or delays due to events like roaming and interference in a mobile robot use case enabled by Wi-Fi 6 TSN. We demonstrate the roaming performance with no delay impact on the applications though simulations of a mobile robot in a factory scenario and experimental results with a mobile robot connected via multiple Wi-Fi 6 radios in a warehouse environment.

This work discusses Access Point Coordination techniques for future 802.11 communications in the context of industrial Wireless TSN scenarios. A Coordinated OFDMA setup is proposed with a frame exchange scheme based on implicit wireless channel sounding prior to transmission. The scheduler assigns resource units to the users, trying to maximize the probability of all the STAs in the network to successfully deliver their data. In order to evaluate the quality of the channels without introducing overhead in the network, we propose a virtual sounding mechanism. We present simulation results first to validate the virtual sounding mechanism and, second, to show the achievable reliability of a Multi-AP network for a set of representative scenarios. These results highlight that Multi-AP can be effectively used to enhance the reliability of the network though special attention must be taken for time-varying scenarios.

With the uprising of new fields such as robotics, IoT or Augmented Reality, one of the main objectives of industrial modernization is the incorporation of safe and secure wireless technologies in the factory floor. However, nowadays wireless protocols can not fulfill the communication requirements of industrial networks, among which reliability and bound guaranteed latency are probably the most stringent ones. The lack of guaranteed low latency and ultra-high reliability of wireless networks are mainly derived from the error-prone nature of wireless propagation. Multi-link techniques are expected to provide enhanced reliability, latency and also protection against external interference. In this work, we assess the reliability and latency enhancement of the Multi-Link technique proposed in 802.11be. The assessment is done through simulation means using realistic industrial propagation and interference models. The results shown in this paper prove that Multi-Link provides an enhancement in wireless reliability and latency.

Many industrial automation systems rely on time-synchronized (and timely) communication among sensing, computing, and actuating devices. Advances in Ethernet enabled by time-sensitive networking (TSN) standards, being developed by the IEEE 802.1 TSN Task Group, are significantly improving time synchronization as well as worst case latencies. Next-generation industrial systems are expected to leverage advances in distributed time coordinated computing and wireless communications to enable greater levels of automation, efficiency, and flexibility. Significant progress has been made in extending accurate time synchronization over the air (e.g., 802.1AS profile for IEEE 802.11/Wi-Fi). Given the inherently unreliable, varying capacity and latency prone characteristics associated with wireless communications, proving the feasibility of worst case latency performance over the wireless medium is a major research challenge. More specifically, understanding what levels of capacity, reliability, and latency could be guaranteed over wireless links with high reliability are important research questions to guide the development of new radios, protocols, and time coordinated applications. This paper provides an overview of the potential applications, requirements, and unique research challenges to extend TSN capabilities over wireless. The paper also describes advances in wireless technologies (e.g., next-generation 802.11 and 5G standards) toward achieving reliable and accurate time distribution and timeliness capabilities. It also provides a classification of wireless applications and a reference architecture for enabling the integration of wired and wireless TSN capabilities in future industrial automation systems.

Estimation of the image location of a mobile LED array transmitter on the camera sensor plane of a digital camera is considered. A Bayesian framework is used to design an initial large measurement matrix over multiple image frames to exploit inter-frame temporal correlations. This large matrix is then factorized into two component matrices; one is used as the front-end measurement matrix with the potential for hardware implementation while the other is designed for software implementation. The factorization can be performed offline through fixed point iterations. The proposed measurement matrix design directly exploits possible transmitter mobility through a parametric framework. The findings are validated through analysis, computer simulation and hardware experiments. Sub-pixel localization accuracy with significant compression is achieved, and the proposed compressive parameter estimation outperforms results obtained using a Gaussian measurement matrix.

A novel type-II hybrid automatic repeat request (HARQ) algorithm over hybrid channels, consisting of parallel free space optical (FSO) and radio frequency (RF) links, is presented. The algorithm uses different jointly optimized puncturing and RF bit selection patterns for different retransmissions. Analytical bit error rate and throughput performance expressions for the algorithm in case of both time invariant and random fading channels for recursive systematic, non-recursive non-systematic convolutional codes and turbo codes are given. Numerical results show a gain of several dBs of the proposed algorithm when compared to HARQ that uses random bit selection for transmission through the RF channel. The performance of the algorithm for different FSO and RF link conditions is demonstrated.

The problem of selecting anchor-cum-relay (ACR) nodes for the dual purpose of tracking a mobile source as well as serving as relays for the source signal is considered. The proposed approach uses particle filters (PFs) with node selection based on the received signal-to-noise ratio (SNR) along with a localization constraint derived through the Fisher information matrix (FIM). The detail steps of implementation are given. A posterior Cramer-Rao lower bound approach is also explored to exploit information from previous node selections. Numerical results demonstrate that the proposed FIM-SNR approach achieves more than 16 dB in average source localization mean-squared error (MSE) over nearest node (NN) selection, while performing very close to FIM-based optimal localization. At the same time, the proposed FIM-SNR provides a received SNR nearly identical to NN selection but outperforming FIM-based selection's SNR by more than 5.5 dB.

Dual-role nodes that can work both as relays and also as anchors for joint communication and source localization are proposed. Selection and power allocation of a few dual-role nodes in the presence of many nodes in the network are considered. A novel approach is proposed that relies on maximizing the signal-to-noise ratio (SNR) at the destination node under a source localization constraint. Bounds on the number of nodes needed to achieve a certain localization performance, a concave bound on SNR at the destination node and a practical algorithm to select the dual-role nodes are presented. To estimate the source location using non- line-of-sight range measurements, a new algorithm using semi- definite programing with relaxation followed by majorization- minimization is presented. The results demonstrate excellent promise for obtaining joint improved bit error rate and mean- squared error localization performance by selecting nodes based on combined SNR and localization constraint.

We investigate the behavior of spatially partially coherent beams (PCBs) in the presence of pointing errors in the space communication environment. Closed form expressions for the optimal coherence length for minimizing outage probability and maximizing average signal-to-noise ratio (SNR) are derived. In the case of outage probablity, we observe that the optimal coherence parameter does not depend on the pointing error statistics. For average SNR results, PCBs can improve performance when large fixed beam offsets are present. We also provide BER performance analysis results for a convolutionally coded system and demonstrate significant performance improvement using PCBs with optimized parameters.

Turbo coded data transmission over a hybrid channel, consisting of parallel free space optical (FSO) and radio frequency (RF) links, is considered, and analytical bit error performance results are derived. The FSO link is modeled using the gamma-gamma distribution function, and both random and block fading channels are used. Random and specific codeword bit selections for transmission through the RF link are considered. Conditions to guarantee bit error rate (BER) performance improvement in hybrid channels over FSO only links are derived. In the case of block fading channels, the hybrid channel using turbo codes is found to provide several dBs of gain in the signal-to-noise ratio (SNR) over an optical only link. A technique to jointly optimize puncturing and RF bit selection patterns for the hybrid channel is also presented. Results demonstrate significant BER performance improvement obtained from the proposed joint optimization approach.