We will review some of the major results in random graphs and some of the more challenging open problems. We will cover algorithmic and structural questions. We will touch on newer models, including those related to the WWW.

Random graphs

It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

The objective of this paper is to give a comprehensive introduction to applied cryptography with an engineer or computer scientist in mind. The emphasis is on the knowledge needed to create practical systems which supports integrity, confidentiality, or authenticity. Topics covered includes an introduction to the concepts in cryptography, attacks against cryptographic systems, key use and handling, random bit generation, encryption modes, and message authentication codes. Recommendations on algorithms and further reading is given in the end of the paper. This paper should make the reader able to build, understand and evaluate system descriptions and designs based on the cryptographic components described in the paper.

[서평]「Applied Cryptography」

IoT security: Review, blockchain solutions, and open challenges

The problem of error control and concealment in video communication is becoming increasingly important because of the growing interest in video delivery over unreliable channels such as wireless networks and the Internet. This paper reviews the techniques that have been developed for error control and concealment. These techniques are described in three categories according to the roles that the encoder and decoder play in the underlying approaches. Forward error concealment includes methods that add redundancy at the source end to enhance error resilience of the coded bit streams. Error concealment by postprocessing refers to operations at the decoder to recover the damaged areas based on characteristics of image and video signals. Last, interactive error concealment covers techniques that are dependent on a dialogue between the source and destination. Both current research activities and practice in international standards are covered.

/pdf/error-control-and-concealment-for-video-communication-a-3tm7c48xjc.pdf

Error control and concealment for video communication: a review

We define authenticated video as decoded video that results from those received packets whose authenticities have been verified. Generic data stream authentication methods usually impose overhead and dependency among packets for verification. Therefore, the conventional rate-distortion (R-D) optimized video streaming techniques produce highly sub-optimal R-D performance for authenticated video, since they do not account for the overhead and additional dependencies for authentication. In this paper, we study this practical problem and propose an Rate-Distortion-Authentication (R-D-A) optimized streaming technique for authenticated video. Based on packets' importance in terms of both video quality and authentication dependencies, the proposed technique computes a packet transmission schedule that minimizes the expected end-to-end distortion of the authenticated video at the receiver subject to a constraint on the average transmission rate. Simulation results based on H.264 JM 10.2 and NS-2 demonstrate that our proposed R-D-A optimized streaming technique substantially outperforms both prior (authentication-unaware) R-D optimized streaming techniques and data stream authentication techniques. In particular, when the channel capacity is below the source rate, the PSNR of authenticated video quickly drops to unacceptable levels using conventional R-D optimized streaming techniques, while the proposed R-D-A Optimization technique still maintains optimized video quality. Furthermore, we examine a low-complexity version of the proposed algorithm, and also an enhanced version which accounts for the multiple deadlines associated with each packet, which is introduced by stream authentication

/pdf/rate-distortion-authentication-optimized-streaming-of-27pjv5vpg5.pdf

Rate-Distortion-Authentication Optimized Streaming of Authenticated Video

The author examines the performance of a packet reservation multiple access (PRMA) protocol in a metropolitan microcellular radio environment using computer simulations. Call characteristics, mobility and channel conditions have an impact on PRMA performance, which is measured in terms of the average packet dropping rate. In order to maintain a reasonable level of service quality for calls in progress, teletraffic loading can be controlled by introducing a call setup queue and limiting the number of active subscribers. Performance comparisons with other protocols are carried out. >

https://ieeexplore.ieee.org/iel2/3171/8992/00397271.pdf

Packet reservation multiple access in a metropolitan microcellular radio environment

Interuser interference occurs when multiple body sensor networks (BSNs) are transmitting simultaneously in close proximity to each other. Interference analysis in BSNs is challenging due to the hybrid medium access control (MAC) and the specific channel characteristics of BSNs. This paper presents a stochastic geometry analysis framework for interuser interference in IEEE 802.15.6 BSNs. An extended Matern point process is proposed to model the complex spatial distribution of the interfering BSNs caused by the hybrid MAC defined in IEEE 802.15.6. We employ a stochastic geometry approach to evaluate the performance of BSNs, considering the specific channel characteristics of BSNs near the human body. Performance metrics are derived in terms of outage probability and spatial throughput in the presence of interuser interference. We conduct performance evaluation through extensive simulations and show that the simulation results fit well with the analytic results. Insights are provided on the determination of the interference detection range, the BSN density, and the design of MAC for BSNs.

/pdf/an-analysis-framework-for-interuser-interference-in-ieee-802-5a97e0upgn.pdf

An Analysis Framework for Interuser Interference in IEEE 802.15.6 Body Sensor Networks: A Stochastic Geometry Approach

In this paper, we propose an optimized content-aware authentication scheme for JPEG-2000 streams over lossy networks, where a received packet is consumed only when it is both decodable and authentic. In a JPEG-2000 codestream some packets are more important than others in terms of coding dependency and visual quality. This inspires us to allocate more redundant authentication information for the more important packets to minimize the distortion of the authenticated image at the receiver. In other words, with the awareness of image content, we formulate an optimization framework, which is able to build an authentication graph yielding the best visual quality at the receiver, given a specific authentication overhead and network condition. Experimental results demonstrate that the proposed scheme achieved our design goals in that the R-D curve of an authenticated image is very close to its original one where no authentication is applied.

/pdf/an-optimized-content-aware-authentication-scheme-for-25xcg64m40.pdf

An Optimized Content-Aware Authentication Scheme for Streaming JPEG-2000 Images Over Lossy Networks

Fingerprint-based localization systems mainly utilize the received signal strength (RSS) to estimate the location of a receiver, and the localization accuracy depends largely on the number and placement of access points (APs). In this paper, we propose a novel method for placing the APs, which aims to minimize the total number of similar fingerprints (SFs) over the entire array of training locations. Minimizing SFs will increase the diversity of RSS array and hence improve localization accuracy. To solve the problem using a simple brute force search would be highly computationally expensive and inefficient. Instead, we propose a heuristic optimization algorithm based on Simulated Annealing (SA). Numerical results are obtained for both the brute force search and the SA based approach. Finally, the proposed algorithm's outputs, i.e., the APs' locations, are used with a K-Nearest Neighbors based localization algorithm, and the resulting localization errors are analyzed.

Wai-Choong Wong

Papers

Rate-Distortion-Authentication Optimized Streaming of Authenticated Video

Packet reservation multiple access in a metropolitan microcellular radio environment

An Analysis Framework for Interuser Interference in IEEE 802.15.6 Body Sensor Networks: A Stochastic Geometry Approach

An Optimized Content-Aware Authentication Scheme for Streaming JPEG-2000 Images Over Lossy Networks

Access point placement for fingerprint-based localization