This paper investigates the ability of modified cooperative adaptive cruise control to support high-density car platooning. We first use a simplistic communication model to study the impact of actuation lag, message periodicity, and communication delay on the minimum feasible inter-car spacing. We then use a detailed IEEE 802.11p simulation model to evaluate platooning performance in realistic highway scenarios. Different highway traffic intensities are simulated to observe the impact of increasing contention on the wireless channel with two different transceiver configurations: a single-transceiver operating on the common safety channel and a dual-transceiver operating, simultaneously, on the common safety channel and a dedicated service channel.

Video multicasting from cameras mounted on micro aerial vehicles (MAVs) is desirable for applications such as search and rescue, surveillance and disaster management. Because of the mobility of the video sources and the high data-rate of videos, the transmission rate should be adapted to the task at hand. Rate-adaptive video multicast streaming in 802.11 requires wireless link estimation as well as frequent feedback from multiple receivers. We propose an application layer rate-adaptive video multicast streaming framework using 802.11 adhoc network that is applicable when both the sender and the receiver nodes are mobile. The receiver nodes of a multicast group are dynamically elected based on their changing link conditions to gain feedback. An Application Layer Video Multicast Gateway (ALVM-GW) adapts the transmission rate and the video encoding rate based on the received feedback. Emulation results show that the proposed approach has balanced performance in terms of goodput, delay and packet loss.

This paper investigates block error rate (BLER) performance and computational complexity of candidate channel coding schemes for ultra-reliable low latency communication (URLLC) in 5G. The considered candidates are the same as those identified in 3GPP: turbo, LDPC, polar, and convolutional codes. Details of code constructions and decoding algorithms are provided with computational complexity analysis. Code construction parameters, number of iterations, and list sizes are selected to provide a fair comparison among candidate coding schemes. Simulation results on BLER are shown for several code rates and small-to-moderate block sizes. The results reveal that polar and LDPC codes outperform turbo codes for short block sizes of 40 bits, while the opposite is true for medium block sizes of 200 bits. None of the schemes is a clear winner at all considered block sizes and coding rates. Other aspects like implementation complexity, latency, and flexibility will also be important when deciding the URLLC coding scheme.

No abstract available.

The Internet of Things (IoT) will connect not only Zigbee-enabled devices but also Wi-Fi-enabled consumer electronics, given the recent rise of IPv6. We developed a power saving communication protocol for low-complexity IPv6-connected devices that can support multiple applications. We demonstrate here in an entertainment-related application scenario how to use that protocol to bring what we refer to as the Internet of Toys to life (Fig. 1).

Wireless multi-hop networks are a promising approach to provide connectivity in areas with sparse wireless infrastructure. In multi-hop networks, data is relayed from one mobile device to another until it reaches the destination (e.g. a Wi-Fi access points). Different hops preferably use different radio channels to avoid interfering with each other. It is not practical to use multiple channels with single-radio devices because the network would suffer from partitioning. The addition of the second radio interface to the devices may simplify the multi-channel management and improve the overall network performance. In this paper, we evaluate the potential benefits of the dual Wi-Fi radio devices in terms of throughput and energy consumption. For the evaluation, we use our Wi-Fi network simulator, Jemula802, extended with the models of multi-channel radio management algorithms.

The majority of sport events are of interest only to a relatively small group of viewers, such as college and regional league competitions. The broadcasting of these sport events is often not economically viable because of the required installation/cabling and the need for an on-site crew for content production. An automated or semi-automated broadcast system with multiple cameras would potentially enable a significant cost reduction. This contribution analyzes to what extent wireless technology simplifies the deployment and reduce the cost of such automated multi-camera systems. We present a networking architecture for wirelessly connected cameras and discuss research challenges and potential solutions. A particular emphasis is given on how emerging wireless technologies can be exploited towards this path and on mechanisms that could be used to relax the system requirements.

We consider how relatively simple extensions of popular channel-aware schedulers can be used to multicast scalable video streams in high speed radio access networks. To support the evaluation, we first describe a model of the channel distortion of scalable video coding and validate it using eight commonly used test sequences. We use the distortion model in a detailed simulation setup to compare the performance of six schedulers, among them the Max-Sum and Max-Prod schedulers, which aim to maximize the sum and the product of streaming utilities, respectively. We investigate how the traffic load, user mobility, layering structure, and users' aversion of fluctuating distortion influence the streaming performance. Our results show that the Max-Sum scheduler performs better than other considered schemes in almost all scenarios. With the Max-Sum scheduler, the gain of scalable video coding compared to non-scalable coding is substantial, even when users do not tolerate frequent changes in video quality.

In this paper, we study the performance of the proportional fair scheduler, which has been proposed for some of the emerging radio access systems. It maximizes the spectral efficiency of the systems, which is a strong incentive for network providers to use it. Our goal is to investigate how the proportional fair scheduling affects the performance of streaming users. Focus is on the throughput-delay trade-offs associated with proportional fair scheduling in CDMA/HDR systems. Special attention is devoted to defining appropriate performance measures and creating a realistic simulation environment. Our results indicate that the opportunistic scheduling may face difficulties in providing the user-level performance in cases where streaming flows constitute a significant share of the traffic load.

One of the central problems in wireless video transmission is the choice of source and channel coding rates to allocate the available transmission rate optimally. In this paper, we present a structural distortion model for video streaming over time-varying fading channels. Based on the model, we study the end-to-end distortion for various bit-rate allocation strategies and channel conditions. We show that the robustness to channel variations is crucial for the streaming performance when frequent bit-rate adaptations are not feasible. It is achieved at the expense of higher source distortion in the encoder. Our findings are illustrated on a practical problem of distortion-optimal selection of transport formats in an adaptive modulation and coding (AMC) scheme used in HSDPA.

In this paper, we study the performance of the proportional fair scheduler, which has been proposed for the emerging 3.5G radio access systems. It maximizes the spectral efficiency of the systems, which is a strong incentive for network providers to use it. Our goal is to investigate whether the proportional fair scheduler also provides benefits to the streaming users. Focus is on the throughput-delay trade-offs associated with video streaming over HSDPA. Special attention is devoted to defining appropriate performance measures and creating a realistic simulation environment. Our results indicate that the opportunistic scheduling faces major difficulties in providing the user-level performance in cases where streaming flows constitute a significant share of the traffic load.

One of the central problems in video transmission over lossy channels is the choice of source and channel coding rates to allocate the available transmission rate optimally. In this paper, we present a structural distortion model for video streaming over time-varying fading channels. Based on this model we study the average video distortion for various bit-rate allocation strategies and channel conditions. We argue that sensitivity to channel variations should be one of the selection criteria when choosing an optimal bit-rate allocation. We demonstrate that a simple bit-rate allocation strategy, which aims to minimize current distortion, is not necessarily optimal in terms of time-average distortion. System robustness is crucial for the streaming performance when frequent allocation updates are not feasible. It is achieved at the expense of higher source distortion in the encoder.