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A 2.4GHz fully-integrated Wi-Fi compliant wake-up receiver in 14nm FinFET technology is presented. The receiver achieves −72dBm sensitivity and +20dBr adjacent channel interference rejection for 62.5kbps at 10−3 BER while consuming 95µW. The OOK-modulated wake-up packet can be transmitted using any legacy OFDM Wi-Fi transmitter.

Wireless video is the main driver for rapid growth in cellular data traffic. Traditional methods for network capacity increase are very costly and do not exploit the unique features of video, especially asynchronous content reuse. In this paper we give an overview of our work that proposed and detailed a new transmission paradigm exploiting content reuse and the widespread availability of low-cost storage. Our network structure uses caching in helper stations (femtocaching) and/or devices, combined with highly spectrally efficient short-range communications to deliver video files. For femtocaching, we develop optimum storage schemes and dynamic streaming policies that optimize video quality. For caching on devices, combined with device-to-device (D2D) communications, we show that communications within clusters of mobile stations should be used; the cluster size can be adjusted to optimize the tradeoff between frequency reuse and the probability that a device finds a desired file cached by another device in the same cluster. In many situations the network throughput increases linearly with the number of users, and the tradeoff between throughput and outage is better than in traditional base-station centric systems. Simulation results with realistic numbers of users and channel conditions show that network throughput can be increased by two orders of magnitude compared to conventional schemes.

One of the primary design goals of wireless multi-media communication systems is to optimize the quality of user experience. This metric is often quantified using the end-to-end distortion between the original source at the encoder and the reconstructed version of it at the destination. Considering this performance metric, optimal multimedia transmission schemes using joint source-channel coding (JSCC) for fading cognitive radio networks are studied in this paper. Different underlay transmission protocols, based on single- or multi-user receiver capabilities, are compared in terms of their average distortion performance, using an outage analysis. It is demonstrated that JSCC provides significant performance gains over goodput-maximizing schemes that rely on the optimality of source-channel separation, and that, for the scenarios evaluated, one of the proposed protocols with JSCC achieves average distortion performance very close to a lower bound obtained by ignoring the primary interference.

In wireless multimedia communications, optimizing the quality of user experience is a major design goal, which is often quantified by the end-to-end distortion between the actual multimedia source at the encoder and its reconstructed version at the decoder. Joint source-channel coding (JSCC) techniques aim to optimize codec and radio system parameters in order to minimize end-to-end distortion and yield enhanced quality of user experience when compared with separate source-channel coding techniques. With the motivation of applying JSCC-based cross-layer optimizations to PHY/MAC layer design for practical wireless systems, this paper proposes new techniques for MIMO link adaptation toward enhanced multimedia communications. In particular, we propose new distortion-aware MIMO link adaptation techniques toward the selection of modulation and coding schemes (MCS) and MIMO space-time modulation (including MIMO diversity and spatial multiplexing) schemes with the objective of minimizing end-to-end distortion, different from classical approaches that aimed for other optimizations such as maximizing spectral efficiency or goodput. Furthermore, we investigate the performance of distortion-aware MIMO link adaptation in realistic link-level simulation (LLS) and system-level simulation (SLS) environments based on orthogonal frequency division multiplexing (OFDM) under broadband frequency-selective fading with special focus on multicast broadcast services (MBS), and demonstrate their advantages over goodput-maximizing MIMO link adaptation techniques in terms of reduced end-to-end distortion and higher peak signal-to-noise ratio (PSNR).

The ability to optimally exploit the 7.5 GHz of newly created nlicensed spectrum for UWB technology depends on addressing a number of challenging system design issues. This chapter provides an overview of many of these issues and some technical trade-offs and comparisons with different system designs. Some of the challenges include dealing with multipath propagation, energy capture, narrowband interference, rapid synchronization, and varying regulatory rules throughout the world, just to name a few.

Worldwide ultra-wideband (UWB) radio regulations are slowly taking shape, and are reaching the final stages of work. The main reasons for the continued debate has of course been the potential interference that can be caused by UWB radios to other radios with which they would share the spectrum. Specifically for the case of broadband wireless access (BWA) systems serving indoor subscriber stations (SS), it has been proposed to impose a require ment that UWB systems should detect and avoid interference to the downlinks of such BWA SS. In this paper we discuss some of the aspects of such solutions, and present some results and description of the ongoing work in this area.

The FCC ruling in 2002 allowing for the unlicensed deployment of ultra-wideband (UWB) devices for communications purposes in the 3.1-10.6 GHz band has sparked great interest in the industry. In particular, the IEEE 802.15.3a task group is currently developing a standard for high-rate, short-range wireless communication systems that is expected to use UWB technology. One of the main challenges for UWB system design is minimizing the possible interference to other narrowband systems, while, at the same time, dealing with the large interference that may be coming from these narrowband systems into the UWB receiver. Traditional UWB systems have used very short time impulses that occupy several giga-hertz of bandwidth. This approach makes it difficult to efficiently avoid other system that may be sharing the same band. This paper will describe a channel model that has been adopted by the industry to evaluate the merits of different UWB physical layer approaches and introduce an alternate approach to a high-rate UWB system that is based upon the concatenation of multiple narrower band UWB waveforms.

Ultrawideband (UWB) is a promising radio technology for networks delivering extremely high data rates at short ranges. In this paper, different approaches to the physical layer system design for such networks are studied, and some of the challenges and opportunities inherent in their design and implementation are compared. For example, the use of extremely short duration pulses offers great possibilities for position location, but makes the timing synchronization task more complex. The ultra-wide bandwidth offers excellent frequency diversity and multipath resolution, but the channel estimation and multipath combining tasks are correspondingly more challenging. A pulse based UWB system (or impulse radio, IR-UWB) and a novel pulsed multicarrier UWB system are compared, emphasizing timing acquisition and performance in multipath. Some other differences, including interference avoidance, equalization, etc. are briefly dealt with.

Multipath propagation for the indoor wireless channel is very complicated and difficult to predict. Several papers have been written attempting to apply an analytical model for this channel to help systems engineers evaluate various architectural components of a wireless system, including modulation, multiple access, and waveform design techniques, without having to resort to empirical data collection. This paper attempts to apply one of these analytical models, known as the /spl Delta/-K model, to help study the performance of an ultra wide band (UWB) system and look at performance trade-offs for different multilevel modulations as well as the benefits of RAKE reception.