HTTP-based Smart Transportation of DNS Queries and Applications

Aziz Mohaisen,Manar Mohaisen 한국산학기술학회 2015 SmartCR Vol.5 No.4

In this paper we introduce a system, called DJSON, which enables HTTP transport of Domain Name System traffic. DJSON enables re-encoding of the existing Domain Name System message format, so that it can traverse hostile territory with confidence without modifying the underlying Domain Name System design. In DJSON, Domain Name System messages are sent and received with a properly formatted HTML using a JSON encoding that allows bidirectional mapping to and from traditional Domain Name System transport encodings. This guarantees that interoperability is no worse than it is today. HTTP can be used to work around the problem where middle boxes have interoperability problems. DJSON aims to solve several real-world and operational problems. DJSON is designed to “bridge” Domain Name System across areas where Domain Name System packets might be mangled, deliberately modified or blocked. DJSON further aims to enable and address improved reliability, availability, and security. Detailed discussions, experiments run on a prototype of DJSON, and analysis show the effectiveness and relevance of our work.

Characterizing Collaboration in Social Network-enabled Routing

( Manar Mohaisen ),( Aziz Mohaisen ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.4

Connectivity and trust in social networks have been exploited to propose applications on top of these networks, including routing, Sybil defenses, and anonymous communication systems. In these networks, and for such applications, connectivity ensures good performance of applications while trust is assumed to always hold, so as collaboration and good behavior are always guaranteed. In this paper, we study the impact of differential behavior of users on performance in typical social network-enabled routing applications. We classify users into either collaborative or rational (probabilistically collaborative) and study the impact of this classification and the associated behavior of users on the performance of such applications, including random walk-based routing, shortest path based routing, breadth-first-search based routing, and Dijkstra routing. By experimenting with real-world social network traces, we make several interesting observations. First, we show that some of the existing social graphs have high routing costs, demonstrating poor structure that prevents their use in such applications. Second, we study the factors that make probabilistically collaborative nodes important for the performance of the routing protocol within the entire network and demonstrate that the importance of these nodes stems from their topological features rather than their percentage of all the nodes within the network.

Transmit Antenna Selection for Multi-user MIMO Precoding Systems with Limited Feedback

Mohaisen, Manar The Korea Institute of Information and Commucation 2011 Journal of information and communication convergen Vol.9 No.2

Transmit antenna selection techniques are prominent since they exploit the spatial selectivity at the transmitter side. In the literature, antenna selection techniques assume full knowledge of the channel state information (CSI). In this paper, we consider that the CSI is not perfectly known at the transmitter; however, a quantized version of the channel coefficients is fed back by the users. We employ the non-uniform Lloyd-Max quantization algorithm which takes into consideration the distribution of the channel coefficients. Simulation results show that the degradation in the BER of the system with imperfect CSI at the transmitter is tolerable, especially when the transmit diversity order is high.

Multiple Antenna Technologies

Mohaisen, Manar,Wang, YuPeng,Chang, Kyung-Hi The Korea Institute of Information and Commucation 2007 정보와 통신 Vol.24 No.5

Multiple antenna technologies have received high attention in the last few decades for their capabilities to improve the overall system performance. Multiple-input multiple-output systems include a variety of techniques capable of not only increase the reliability of the communication but also impressively boost the channel capacity. In addition, smart antenna systems can increase the link quality and lead to appreciable interference reduction.

Leakage of .onion at the DNS Root: Measurements, Causes, and Countermeasures

Mohaisen, Aziz,Ren, Kui IEEE 2017 IEEE/ACM transactions on networking Vol.25 No.5

<P>The Tor hidden services, one of the features of the Tor anonymity network, are widely used for providing anonymity to services within the Tor network. Tor uses the .onion pseudo-top-level domain for naming convention and to route requests to these hidden services. The .onion namespace is not delegated to the global domain name system (DNS), and Tor is designed in such a way that all .onion queries are routed within the Tor network. However, and despite the careful design of Tor, numerous .onion requests are still today observed in the global DNS infrastructure, thus calling for further investigation. In this paper, we present the state of .onion requests received at the global DNS and as viewed from two large DNS traces: a continuous period of observation at the A and J DNS root nodes over a longitudinal period of time and a synthesis of Day In The Life of the Internet data repository that gathers a synchronized DNS capture of two days per year over multiple years. We found that .onion leakage in the DNS infrastructure to be both prevalent and persistent. Our characterization of the leakage shows various features, including high volumes of leakage that are diverse, geographically distributed, and targeting various types of hidden services. Furthermore, we found that various spikes in the .onion request volumes can be correlated with various global events, including geopolitical events. We attribute the leakage to various causes that are plausible based on various assessments, and provide various remedies with varying benefits.</P>

A Review of Fixed-Complexity Vector Perturbation for MU-MIMO

Mohaisen, Manar Korea Information Processing Society 2015 Journal of information processing systems Vol.11 No.3

Recently, there has been an increasing demand of high data rates services, where several multiuser multiple-input multiple-output (MU-MIMO) techniques were introduced to meet these demands. Among these techniques, vector perturbation combined with linear precoding techniques, such as zero-forcing and minimum mean-square error, have been proven to be efficient in reducing the transmit power and hence, perform close to the optimum algorithm. In this paper, we review several fixed-complexity vector perturbation techniques and investigate their performance under both perfect and imperfect channel knowledge at the transmitter. Also, we investigate the combination of block diagonalization with vector perturbation outline its merits.

Structures for Communication-Efficient Public Key Revocation in Ubiquitous Sensor Network

Mohaisen, A.,Nyang, D.,Maeng, Y.,Lee, K. SPRINGER-VERLAG 2007 Lecture Notes in Computer Science Vol.- No.4864

Co-Channel Interference Cancellation in Cellular OFDM Networks PART II: Co-Channel Interference Cancellation in Single Frequency OFDM Networks using Soft Decision MLE CCI Canceler

Mohaisen, Manar,Chang, Kyung-Hi The Korea Institute of Information and Commucation 2007 韓國通信學會論文誌 Vol.32 No.7a

본 논문에서는 OFDM 셀룰라 네트워크에서 셀 가장자리에 위치한 사용자를 위한 다운링크 동일채널간섭(CCI) 제거 기법을 소개한다. 기지국간의 협력적 심볼 전송은 동일 심볼을 다른 기지국에서 상이한 부반송파를 사용하여 전송함으로서 이루어진다. 단말기에서는 전송된 심볼을 추정하기 위하여 연판정 최대우도 동일채널간섭 제거기(soft decision maximum likelihood CCI canceler)와 수정된 최대비 합성법 (modified maximum ratio combining (M-MRC))을 적용하며, 합성법에 사용된 가중치는 협력 기지국과 단말기 사이의 채널 상수에 의해서 유도된다. 시뮬레이션 결과로부터 제안된 기법이 주파수 선택적 페이딩 채널과 주파수 비선택적 페이딩 채널에서 각기 9 dB와 6dB의 SIR 이득을 보임을 알 수 있다. In this paper, a new scheme of downlink co-channel interference (CCI) cancellation in OFDM cellular networks is introduced for users at the cell-edge. Coordinated symbol transmission between base stations (BS) is operated where the same symbol is transmitted from different BS on different sub-carriers. At the mobile station (MS) receiver, we introduce a soft decision maximum likelihood CCI canceler and a modified maximum ratio combining (M-MRC) to obtain an estimate of the transmitted symbols. Weights used in the combining method are derived from the channels coefficients between the cooperated BSs and the MS. Simulations show that the proposed scheme works well under frequency-selective channels and frequency non-selective channels. A gain of 9 dB and 6 dB in SIR is obtained under multipath fading and flat-fading channels, respectively.

Fixed-Complexity Sphere Encoder for Multi-User MIMO Systems

Mohaisen, Manar,Chang, Kyung-Hi The Korea Institute of Information and Commucation 2011 Journal of communications and networks Vol.13 No.1

In this paper, we propose a fixed-complexity sphere encoder (FSE) for multi-user multi-input multi-output (MU-MIMO) systems. The proposed FSE accomplishes a scalable tradeoff between performance and complexity. Also, because it has a parallel tree-search structure, the proposed encoder can be easily pipelined, leading to a tremendous reduction in the precoding latency. The complexity of the proposed encoder is also analyzed, and we propose two techniques that reduce it. Simulation and analytical results demonstrate that in a $4{\times}4$ MU-MIMO system, the proposed FSE requires only 11.5% of the computational complexity needed by the conventional QR decomposition with M-algorithm encoder (QRDM-E). Also, the encoding throughput of the proposed encoder is 7.5 times that of the QRDM-E with tolerable degradation in the BER performance, while achieving the optimum diversity order.

Co-Channel Interference Cancellation in Cellular OFDM Networks - PART I : Maximum-Likelihood Co-Channel Interference Cancellation with Power Control for Cellular OFDM Networks

Mohaisen, Manar,Chang, Kyung-Hi The Korea Institute of Information and Commucation 2007 韓國通信學會論文誌 Vol.32 No.5A

In cellular orthogonal frequency division multiplexing (OFDM) networks, co-channel interference (CCI) leads to severe degradation in the BER performance. To solve this problem, maximum-likelihood estimation (MLE) CCI cancellation scheme has been proposed in the literature. MLE CCI cancellation scheme generates weighted replicas of the transmitted signals where weights represent the estimated channel transfer functions. The replica with the smallest Euclidean distance from the received signal is selected and data are detected. When the received power of the desired and interference signals are nearly the same, the BER performance is degraded. In this paper, we propose a closed-loop power control (PC) scheme capable of detecting the equal received power situation at the mobile station (MS) receiver by using the newly introduced parameter power ratio (PR). When this situation is detected, the MS sends a feedback to the desired base station (BS) which boosts the transmission power in the next frame. At cell edge where signal to interferer ratio (SIR) is considered to have average value between -5 dB and 10 dB, computer simulations show that the proposed CCI cancellation scheme has a gain of 7 dB at 28 Km/h.