Indoor wireless ranging localization is a promising approach for low-power and high-accuracy localization of wearable devices. A primary challenge in this domain stems from non-line of sight propagation of radio waves. This study tackles a fundamental issue in wireless ranging: the unpredictability of real-time multipath determination, especially in challenging conditions such as when there is no direct line of sight. We achieve this by fusing range measurements with inertial measurements obtained from a low cost Inertial Measurement Unit (IMU). For this purpose, we introduce a novel asymmetric noise model crafted specifically for non-Gaussian multipath disturbances. Additionally, we present a novel Levenberg-Marquardt (LM)-family trust-region adaptation of the iSAM2 fusion algorithm, which is optimized for robust performance for our ranging-IMU fusion problem. We evaluate our solution in a densely occupied real office environment. Our proposed solution can achieve temporally consistent localization with an average absolute accuracy of ∼0.3m in real-world settings. Furthermore, our results indicate that we can achieve comparable accuracy even with infrequent range measurements down to 1Hz.

Smart glasses that support augmented reality (AR) have the potential to become the consumer's primary medium of connecting to the future internet. For the best quality of user experience, AR glasses must have a small form factor and long battery life, while satisfying the data rate and latency requirements of AR applications. To extend the AR glasses' battery life, the computation and processing involved in AR may be offloaded to a companion device, such as a smartphone, through a wireless connection. Sidelink (SL), i.e., the D2D communication interface of 5G NR, is a potential candidate for this wireless link. In this paper, we use system-level simulations to analyze the feasibility of NR SL for supporting AR. Our simulator incorporates the PHY layer structure and MAC layer resource scheduling of 3GPP SL, standard 3GPP channel models, and MCS configurations. Our results suggest that the current SL standard specifications are insufficient for high-end AR use cases with heavy interaction but can support simpler previews and file transfers. We further propose two enhancements to SL resource allocation, which have the potential to offer significant performance improvements for AR applications.

In this paper, we propose a cross-layer distributed power control and scheduling protocol for delay-constrained applications over mobile CDMA-based ad hoc wireless networks. Herein, we propose a novel scheme where power control is employed to combat delay occurring on multi-hop wireless ad hoc networks via cross-layer information exchange. Based on that, a distributed power control and scheduling protocol is proposed to control the incurred delay as well as the multiple access interference (MAI). Unlike other previous work on power control and scheduling, we also investigate the impact of Doppler spread upon the system performance, and provide a robust system which employs a combination of power control, and coding/interleaving to combat the effects of Doppler spread by exploiting the time diversity when the Doppler spread gets large. Hence, our proposed approach can function appropriately over a wide range of channel conditions.

In this paper, we investigate the issue of cooperative node selection in MIMO communications for wireless ad hoc/sensor networks, where a source node is surrounded by multiple neighbors and all of them are equipped with a single antenna. Given energy, delay and data rate constraints, a source node dynamically chooses its cooperating nodes from its neighbors to form a virtual MIMO system with the destination node (which is assumed to have multiple antennas), as well as adaptively allocates the power level and adjusts the constellation size for each of the selected cooperative nodes. In order to optimize system performance, we jointly consider the optimization of all these parameters, given the aforementioned system constraints. We assume that the source node either has CSI, or has no CSI. Heuristic algorithms, such as maximal channel gain (MCG) and least channel correlation (LCC) algorithms are proposed in order to exploit available system information and to solve the constrained optimization problem.

In this paper, we investigate the performance of opportunistic scheduling for delivering multicast information in an OFDM-based cellular network. The problem is formulated as a system throughput maximization problem subject to the fairness constraints derived from each user's specific minimum QoS requirement. As a solution we design an opportunistic scheduling algorithm based on a priority metric that follows an exponential rule. The metric takes into account the current channel state information to take advantage of the better channel states observed by different subsets of the multicast users at different time slots and sub-bands in order to increase the system throughput. The metric also explicitly includes a term to compensate the deviations observed by individual users from their QoS targets. Hence, our proposed algorithm jointly considers two issues in multicasting: throughput maximization and fairness in terms of the targeted QoS levels. In the paper, we further investigate the impact of feedback frequency on the system performance. For scenarios where feedback is not available for every time slot, a probabilistic scheduling algorithm is proposed based on a finite state Markov channel (FSMC) that models the underlying fading channel. Our simulation results show that our algorithm can achieve significantly better performance compared to other commonly used algorithms. Moreover, the solution can also achieve graceful performance degradation when CSI feedback is not available at every time slot.

In this paper, we investigate the issue of cooperative node selection in MIMO communications for wireless ad hoc/sensor networks, where a source node is surrounded by multiple neighbors and all of them are equipped with a single antenna. Given energy, delay and data rate constraints, a source node dynamically chooses its cooperating nodes from its neighbors to form a virtual MIMO system with the destination node (which is assumed to have multiple antennas), as well as adaptively allocates the power level and adjusts the constellation size for each of the selected cooperative nodes. In order to optimize system performance, we jointly consider the optimization of all these parameters, given the aforementioned system constraints. We assume that the source node either has CSI, or has no CSI. Heuristic algorithms, such as maximal channel gain (MCG) and least channel correlation (LCC) algorithms are proposed in order to exploit available system information and to solve the constrained optimization problem.

In this paper, we propose a cognitive radio based multi-user resource allocation framework for mobile ad hoc networks using multi-carrier DS CDMA modulation over a frequency-selective fading channel. In particular, given preexisting communications in the spectrum where the system is operating, in addition to potential narrow-band interference, a channel sensing and estimation mechanism is provided to obtain information such as subcarrier availability, noise power and channel gain. Given this information, both frequency spectrum and power are allocated to emerging new users (i.e., cognitive radio users), based on a distributed multi-user resource allocation framework, in order to satisfy a target data rate and a power constraint of each cognitive radio user, while attempting to avoid interference to the existing communications as well as to minimize total power consumption of the cognitive radio users.

In this paper, we consider the lifetime maximization problem in a wireless cognitive radio sensor network, where the joint design of cognitive radio and multi-carrier modulation is proposed to achieve high power efficiency. Sensor nodes first sense the entire spectrum and locate the available subcarriers based on a pilot tone detection scheme. After each node locates the available subcarrier set, information is transmitted over the favorite channel that has the largest channel gain. Under this setting, an adaptive modulation strategy is proposed to maximize the network lifetime by selecting the optimal constellation size. Simulation results demonstrate the effectiveness of our approach. In addition, the impact of conflicting transmissions upon the network lifetime is also investigated.

We investigate an embedded multicast/broadcast approach for transport of digital video over spread-spectrum code-division multiple access (CDMA) cellular networks. Previous work has shown that the incorporation of a scalable source coding scheme with multiresolution modulation provides a promising design paradigm for the practical realization of the information-theoretic performance predictions originally developed by Cover, which demonstrated that optimal multicast/broadcast performance could be achieved by an embedded transmission scheme. Hence, the major technical challenge associated with the design of an end-to-end embedded multicast/broadcast system is how to match an embedded modulation constellation with a scalable source coding scheme. In this work, taking into consideration both the interference-limited and bandwidth-limited characteristics of a CDMA system, we provide a cross-layer approach incorporating adaptive power allocation and channel coding strategies and effectively match a discrete cosine transform based scalable motion-compensated video encoder to an embedded multiresolution modulation scheme to simultaneously deliver a basic quality-of-service (QoS) to less capable receivers while maximizing both the QoS for more capable receivers and the system capacity. We demonstrate the efficacy of this approach using the ITU-T H.263+ video scalable hybrid coder, although the approach is generally extensible to other scalable coding schemes as well

In this work, we consider the delivery of digital video over future 3G wireless IP networks and we propose a low-complexity adaptive motion-based unequal error protection (UEP) video coding and transmission system which efficiently combines three existing error-resilience techniques by exploiting knowledge of the source material as well as the channel operating conditions. Given this information, the proposed system can adaptively adjust the operating parameters of the video source encoder and the forward error correction (FEC) channel encoder to maximize the delivered video quality based upon both application-layer video motion estimates and link-layer channel estimates. We demonstrate the efficacy of this approach using the ITU-T H.264 video source coder. The results indicate that a significant performance improvement can be achieved with enhanced resilience to inaccurate channel feedback information and with substantially reduced computational complexity compared to competing approaches

In wireless networks, channel state information is hard to obtain in a reliable and timely manner due to the rapid change of wireless environments. In this paper we propose instead the use of source information, which is always available at the encoder and can be easily and accurately obtained from video sequences, to achieve error-resilience. With use of exponential weighted moving average (EWMA) estimation for the motion-level information associated with video frames, a source-adaptive intra-coding rate selection scheme is described to provide error-resilience to N successive video frames. Based on our proposed cross-layer packetization scheme, a novel intra-frame packet interleaving scheme is implemented together with a fixed FEC coding strategy at the application-layer to combat the severe bursty losses over wireless channels, and the performance of the combined approach is investigated. Our objective and subjective results demonstrate the effectiveness of our approach in dealing with the bursty packet losses on both wireless single-hop and multi-hop networks without any additional system complexity or delay.

For video communications over wireless ad-hoc networks, there are fundamentally two different kinds of packet losses: packet losses due to channel over-pumping, where the operating transmission rate is higher than the prevailing channel capacity, and packet losses due to transmission errors. To eliminate the first kind of packet losses, rate-control is necessary in order to adapt to the time-varying channel capacity. For the second kind of packet losses, error-resilient coding techniques should be used. In this paper, we propose a cross-layer rate-control scheme based on an analytical study of how the effective video transmission rate is affected by the prevailing operating parameters. Furthermore, in order to provide error-resilient real-time video delivery over such wireless ad-hoc networks, a cross-layer delay-constrained joint source-channel coding (JSCC) approach, to be used in conjunction with rate-control, is proposed and investigated. Simulation results demonstrate the effectiveness of this combination of cross-layer rate-control and delay-constrained JSCC for supporting error-resilient video delivery over wireless ad-hoc networks operating under a delay constraint.

In this paper, we investigate the effect of path correlation on video communications when path-diversity routing techniques are employed together with forward error correction (FEC). We study the statistical properties of packet losses when correlation between paths exists and demonstrate that the effects of path correlation on received video quality depend on various factors, such as the effectiveness of error control strategies (passive error concealment, FEC, etc.) and the existing channel conditions. We demonstrate that, contrary to common belief, path correlation need not be detrimental to the system performance. The results are expected to have some impact on the development of explicit multi-path routing strategies.

Packet video transmission over wireless networks is expected to experience packet losses due to noise, interference, multipath and the motion of mobile hosts. Such packet losses often occur in bursts which may cause substantial degradation to the transmitted video quality. In this paper, we propose the use of a cross-layer unequal error protection (UEP) approach which is achieved by assigning an unequal amount of forward error correction (FEC) to each group of link-layer packets according to the corresponding motion level of the slice acquired at the application layer. Also, a novel packetization scheme and an intraframe packet interleaving scheme are proposed to be used together with FEC/UEP in order to combat the bursty packet losses in 3G wireless environments. Our results demonstrate that the proposed approach is very effective in dealing with the packet losses occurring on wireless networks without incurring any additional implementation complexity or delay.