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.

Coding and diversity are very effective techniques for improving transmission reliability in a mobile wireless environment. The use of diversity is particularly important for multimedia communications over fading channels. In this work, we study the transmission of progressive image bitstreams using channel coding in a 2-D time-frequency resource block in an OFDM network, employing time and frequency diversities simultaneously. In particular, in the frequency domain, based on the order of diversity and the correlation of individual subcarriers, we construct symmetric n -channel FEC-based multiple descriptions using channel erasure codes combined with embedded image coding. In the time domain, a concatenation of RCPC codes and CRC codes is employed to protect individual descriptions. We consider the physical channel conditions arising from various coherence bandwidths and coherence times, leading to a range of orders of diversities available in the time and frequency domains. We investigate the effects of different error patterns on the delivered image quality due to various fade rates. We also study the tradeoffs and compare the relative effectiveness associated with the use of erasure codes in the frequency domain and convolutional codes in the time domain under different physical environments. Both the effects of intercarrier interference and channel estimation errors are included in our study. Specifically, the effects of channel estimation errors, frequency selectivity and the rate of the channel variations are taken into consideration for the construction of the 2-D time-frequency block. We provide results showing the gain that the proposed model achieves compared to a system without temporal coding. In one example, for a system experiencing flat fading, low Doppler, and imperfect CSI, we find that the increase in PSNR compared to a system without time diversity is as much as 9.4 dB.

In this paper, we study multiple description (MD) coding and transport for real-time video using multiple asymmetric paths in a packetized network. In particular, we construct the motion- compensated (MC) MD codes using MC-FGS video coder, based on the statistical characteristics and the asymmetry of the multiple routing paths. The MCMDs are the optimally allocated to the multiple paths to minimize the end-to-end video distortion. Simulation results demonstrate that the proposed video transport system can achieve improved performance in both end user quality-of-service and error resilience.

Motion-compensated fine-granularity scalability (MC-FGS) with leaky prediction has been shown to provide an efficient tradeoff between compression gain and error resilience, facilitating the transmission of video over dynamic channel conditions. In this paper, we propose an n-channel symmetric motion-compensated multiple description (MD) coding and transmission scheme for the delivery of scalable video over orthogonal frequency division multiplexed systems, utilizing the concepts of partial and leaky predictions. We investigate the proposed MD coding and transmission scheme using a cross-layer design perspective. In particular, we construct the symmetric motion-compensated MD codes based on the diversity order of the channel, defined as the ratio of the overall bandwidth of the system to the coherence bandwidth of the channel. We show that knowing the diversity order of a physical channel can assist an MC-FGS video coder in selecting the motion-compensation prediction point, as well as on the use of leaky prediction. More importantly, we illustrate how the side information can reduce the drift management problem associated with the construction of symmetric motion-compensated MD codes. We provide results based on both an information-theoretic approach and simulations.

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

We propose an analytical model to study the overall effectiveness of packet-level FEC in improving delay-constrained video transport over wired networks subject to random loss and delay. In particular, we provide an exact analysis for the effect of the additional delay resulting from FEC coding/ decoding on end-to-end video transmission quality. The effects of several key system parameters on the effectiveness of FEC are investigated and the tradeoffs associated with choice of these parameters are demonstrated by some specific numerical examples.

We propose a joint source-coding power-control approach combined with joint source-channel coding employing the class of rate-compatible codes for video transport over code-division multiple-access networks. We show that this cross-layer approach can provide improved spectral efficiency and network use while exhibiting graceful degradation characteristics with an increasing number of users.

Diversity can be used to combat multipath fading and improve the performance of wireless multimedia communication systems. In this work, by considering transmission of an embedded bitstream over an orthogonal frequency division multiplexing (OFDM) system in a slowly varying Rayleigh faded environment, we develop a cross-layer diversity technique which takes advantage of both multiple description coding and frequency diversity techniques. More specifically, assuming a frequency-selective channel, we study the packet loss behavior of an OFDM system and construct multiple independent descriptions using an FEC-based strategy. We provide some analysis of this cross-layer approach and demonstrate its superior performance using the set partitioning in hierarchical trees image coder.

Diversity can be used to combat multipath fading and improve the performance of mobile wireless multimedia communication systems. In this work, by considering transmission of an embedded bitstream over a slow varying Rayleigh faded environment, we develop a cross-layer diversity technique which takes advantage of both multiple description source coding and frequency diversity techniques. More specifically, assuming a frequency-selective channel, we study the packet loss behavior of an OFDM system and construct multiple independent descriptions using an FEC-based strategy. We demonstrate the superior performance of this approach using the set partitioning in hierarchical trees (SPIHT) coder.

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.

We study a problem in cross-layer optimization for video delivery over CDMA networks. By considering the resource requirements as the aggregate of the products of source coding rates and the energy per information bit to noise ratio, we propose a joint source coding-power control (JSCPC) strategy combined with joint source-channel coding (JSCC) employing the class of rate-compatible punctured turbo (RCPT) codes to provide forward error correction with unequal error protection (FEC/UEP). We show that this cross-layer approach can simultaneously maximize the quality of the delivered video while minimizing the total resource consumption, thereby providing improved spectral efficiency and network utilization. We demonstrate the efficacy of this approach using the ITU-T H.263+ video source coder.

We consider future generation wireless code-division multiple-access (CDMA) cellular networks supporting heterogeneous compressed video traffic and investigate transport schemes for maximizing the number of users that can be supported in a single cell while simultaneously maximizing the reconstructed video quality of individual users. More specifically, we demonstrate that the network resources consumed by an individual user in a spread-spectrum CDMA network can be taken as the product of the allocated source-coding rate R/sub s/ and the energy per bit normalized to the multiple-access interference noise density /spl gamma/b. We propose a joint source coding and power control (JSCPC) approach for allocating these two quantities to an individual user, subject to a constraint on the total available bandwidth, to simultaneously maximize the per-cell capacity while maximizing the quality of the delivered video to individual users. We demonstrate the efficacy of this approach using the ITU-T H.263+ video source coder, although the approach is generally applicable to other source-coding schemes as well. The results indicate a significant improvement in delivered quality-of-service (QoS), measured in terms of the end-user average peak signal-to-noise ratio, that can be achieved at a given level of network loading. Furthermore, we demonstrate that without an appropriate JSCPC strategy the traditional soft-capacity limit associated with CDMA networks is no longer present. Indeed, a precipitous decrease in performance can be expected with increasing load. We show that this behavior can be avoided with the proposed JSCPC approach, thereby significantly extending the useful capacity of the CDMA network while exhibiting a more graceful degradation pattern under increasing load.

We investigate the transport of scalable digital video over future third-generation (3G) wireless CDMA cellular systems By considering the resource requirements as the aggregate of the products of source coding rates and the energy per information bit to noise ratio, we propose a joint source coding and power control (JSCPC) scheme which simultaneously maximizes the quality of the delivered video while minimizing the total resource consumption. We demonstrate the efficacy of this approach using the ITU-T H.263+ video source coder, although the approach is generally applicable to other source coding schemes as well.