Proposed Fuzzy Real-Time HaPticS Protocol Carrying Haptic Data and Multisensory Streams

Sensory and haptic data transfers to critical real-time applications over the Internet require better than best effort transport, strict timely and reliable ordered deliveries. Multi-sensory applications usually include video and audio streams with real-time control and sensory data, which aggravate and compress within real-time flows. Such real-time are vulnerable to synchronization to synchronization problems, if combined with poor Internet links. Apart from the use of differentiated QoS and MPLS services, several haptic transport protocols have been proposed to confront such issues, focusing on minimizing flows rate disruption while maintaining a steady transmission rate at the sender. Nevertheless, these protocols fail to cope with network variations and queuing delays posed by the Internet routers. This paper proposes a new haptic protocol that tries to alleviate such inadequacies using three different metrics: mean frame delay, jitter and frame loss calculated at the receiver end and propagated to the sender. In order to dynamically adjust flow rate in a fuzzy controlled manners, the proposed protocol includes a fuzzy controller to its protocol structure. The proposed FRTPS protocol (Fuzzy Real-Time haPticS protocol), utilizes crisp inputs into a fuzzification process followed by fuzzy control rules in order to calculate a crisp level output service class, denoted as Service Rate Level (SRL). The experimental results of FRTPS over RTP show that FRTPS outperforms RTP in cases of congestion incidents, out of order deliveries and goodput

Making video chat robust to packet loss

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.Cataloged from PDF version of thesis.Includes bibliographical references (p. 77-83).Video chat is increasingly popular among Internet users (e.g. Skype, Windows Live Messenger, Google Talk). Often, however, chatting sessions suffer from packet loss, which causes video outage and poor quality. Existing solutions however are unsatisfying. Retransmissions increase the delay and hence can interact negatively with the strict timing requirements of interactive video. FEC codes introduce extra overhead and hence reduce the bandwidth available for video data even in the absence of packet loss. In this thesis, we present ChitChat, a new approach for reliable video chat that neither delays frames nor introduces bandwidth overhead. The key idea is to ensure that the information in each packet describes the whole frame. As a result, even when some packets are lost, the receiver can still use the received packets to decode a smooth version of the original frame. This reduces frame loss and the resulting video freezes and improves the perceived video quality. We have implemented ChitChat and evaluated it over multiple Internet paths. In comparison to Windows Live Messenger 2009, our method reduces the occurrences of video outage events by more than an order of magnitude.by Jue Wang.S.M

Performance Evaluation and Analysis of Mimo Schemes in LTE Networks Environment

RÉSUMÉ Dans cette thèse, nous proposons d'évaluer et d’analyser les performances des configurations radio à antennes multiples à l'émission et/ou la réception (MIMO) dans l’environnement des réseaux LTE (Long Term Evolution). Plus spécifiquement, on s’intéresse à la couche physique de l'interface radio OFDM-MIMO de ces réseaux. Après une introduction rapide aux réseaux LTE et aux techniques MIMO, on présente dans une première étape, une analyse théorique du taux d'erreur binaire en fonction du rapport signal sur bruit des deux principaux codes spatio-temporels de la norme LTE, à savoir le codage SFBC 21 (Space Frequency Block Coding) et le codage FSTD 42 (Frequency Switch Transmit Diversity). On développe les équations analytiques du taux d'erreur binaire de ces codes dans un canal à évanouissement de Rayleigh sans corrélation spatiale qui sont par la suite comparées à des valeurs obtenues par simulations Monte-Carlo. Dans une deuxième étape, on considère l’évaluation de la capacité du canal résultant de l’utilisation de ces mêmes codes dans un canal à évanouissement de Rayleigh. Pour fin de comparaison, on propose par la suite d’évaluer par simulation leur débit effectif. Les résultats montrent que la capacité peut effectivement être presque atteinte en pratique. Le deuxième volet de cette thèse considère les performances des systèmes MIMO utilisant la sélection d’antennes. Nous utilisons la théorie d'ordre statistique pour développer des équations analytiques relatives au taux d’erreur binaire des systèmes avec sélection d'antennes du coté récepteur dans un canal d'évanouissement de Rayleigh sans corrélation spatiale. Afin de valider numériquement les résultats de notre analyse, un algorithme à sélection d’antenne au récepteur a été développé et utilisé en simulation. Dans un dernier temps, on évalue l'effet de la corrélation spatiale entre les antennes. L’étude est faite à partir de simulations et d’un modèle de corrélation spatiale basé sur le produit Kronecker de deux matrices de corrélation relatives respectivement à l'émission et à la réception.----------ABSTRACT This thesis considers both an analysis and a numerical evaluation of the performance of MIMO radio systems in the LTE network environment. More specifically we consider the physical layer of the OFDM-MIMO based radio interface. As a first step we present a theoretical analysis of the bit error rate of the two space-time codes adopted by the LTE norm, namely the SFBC 21 and FSTD 42 codes, as a function of the signal upon noise ratio. Analytical expressions are given for transmission over a Rayleigh channel without spatial correlation which are then compared with Monte-Carlo simulations. As a second step, we consider the capacity of the channel obtained by using these codes on a Rayleigh fading channel. Results show that simulated throughput almost reaches the capacity limit. As a different topic, this thesis considers also MIMO systems based on antenna selection. By using order statistics we develop analytical expressions for the error rate on a Rayleigh channel without antenna correlation. In order to validate our numerical results, an algorithm implementing antenna selection at the receiver has been developed and used in the simulations. As a last step the effect of antenna correlation is investigated through the use of simulations and a model of spatial antenna correlation based on the Kronecker product of two correlation matrices related to the transmitting and receiving elements of the MIMO scheme

Cooperative diversity techniques for high-throughput wireless relay networks

Relay communications has attracted a growing interest in wireless communications with application to various enhanced technologies. This thesis considers a number of issues related to data throughput in various wireless relay network models. Particularly, new implementations of network coding (NC) and space-time coding (STC) techniques are investigated to offer various means of achieving high-throughput relay communications. Firstly, this thesis investigates different practical automatic repeat request (ARQ) retransmission protocols based on NC for two-way wireless relay networks to improve throughput efficiency. Two improved NC-based ARQ schemes are designed based on go-back-N and selective-repeat (SR) protocols. Addressing ARQ issues in multisource multidestination relay networks, a new NC-based ARQ protocol is proposed and two packet-combination algorithms are developed for retransmissions at relay and sources to significantly improve the throughput. In relation to the concept of channel quality indicator (CQI) reporting in two-way relay networks, two new efficient CQI reporting schemes are designed based on NC to improve the system throughput by allowing two terminals to simultaneously estimate the CQI of the distant terminal-relay link without incurring additional overhead. The transmission time for CQI feedback at the relays is reduced by half while the increase in complexity and the loss of performance are shown to be negligible. Furthermore, a low-complexity relay selection scheme is suggested to reduce the relay searching complexity. For the acknowledgment (ACK) process, this thesis proposes a new block ACK scheme based on NC to significantly reduce the ACK overheads and therefore produce an enhanced throughput. The proposed scheme is also shown to improve the reliability of block ACK transmission and reduce the number of data retransmissions for a higher system throughput. Additionally, this thesis presents a new cooperative retransmission scheme based on relay cooperation and NC to considerably reduce the number of retransmission packets and im- prove the reliability of retransmissions for a more power efficient and higher throughput system with non-overlapped retransmissions. Moreover, two relay selection schemes are recommended to determine the optimised number of relays for the retransmission. Finally, with respect to cognitive wireless relay networks (CWRNs), this thesis proposes a new cooperative spectrum sensing (CSS) scheme to improve the spectrum sensing performance and design a new CSS scheme based on NC for three-hop CWRNs to improve system throughput. Furthermore, a new distributed space-time-frequency block code (DSTFBC) is designed for a two- hop nonregenerative CWRN over frequency-selective fading channels. The proposed DSTFBC design achieves higher data rate, spatial diversity gain, and decoupling detection of data blocks at all destination nodes with a low-complexity receiver structure

Network Science for IoT

The research work presented in this thesis is based on the concept and defintion of network that can spread in several and different real world contexts. Indeed, we can refer to a network in a telecommunications sense considering a collection of transmitters, receivers, and communication channels that send or are used to send information to one another. However, as a matter of fact, in nature there are other several examples of networks: the human brain is one of them. The relationship between the actors in Hollywood can be studied in terms of network as well, a generic social community can be compared to a network, eco-systems are networks of species. The recent Network Science aims at studying all these systems using a set of common mathematical methods. In the following of the thesis, we will focus on some of well known telecommunications networks issues using standard telecommunications procedures to address them, with relevant reference to video flow transmissions and management of electric vehicles networks. At the same time, different models aiming at reach the same goals in contexts that may differ from a telecommunications setup can be used. In more details, we will evaluate queueing systems, jamming problems, groups recognition in networks, and mobile computing using game theoretic approaches. It is worth noting that this aspect can be also seen in a reverse order. Indeed, we will discuss how standard telecommunications analysis can be used to investigate on problems not directly related to a telecommunications background. In particular, one of our future purposes is to investigate on the brain connectivity that is raising significant interest in the recent scientific society

Hybrid token-CDMA MAC protocol for wireless networks.

Thesis (Ph.D.)-University of KwaZulu-Natal, Durban, 2009.Ad hoc networks are commonly known to implement IEEE 802.11 standard as their medium access control (MAC) protocol. It is well known that token passing MAC schemes outperform carrier-sense-multiple-access (CSMA) schemes, therefore, token passing MAC protocols have gained popularity in recent years. In recent years, the research extends the concept of token passing ' scheme to wireless settings since they have the potential of achieving higher channel utilization than CSMA type schemes. In this thesis, a hybrid Token-CDMA MAC protocol that is based on a token passing scheme with the incorporation of code division multiple access (CDMA) is introduced. Using a dynamic code distribution algorithm and a modified leaky-bucket policing system, the hybrid protocol is able to provide both Quality of Service (QoS) and high network resource utilization, while ensuring the stability of a network. This thesis begins with the introduction of a new MAC protocol based on a token-passing strategy. The input traffic model used in the simulation is a two-state Markov Modulated Poisson Process (MMPP). The data rate QoS is enforced by implementing a modified leaky bucket mechanism in the proposed MAC scheme. The simulation also takes into account channel link errors caused by the wireless link by implementing a multi-layered Gilbert-Elliot model. The performance of the proposed MAC scheme is examined by simulation, and compared to the performance of other MAC protocols published in the literature. Simulation results demonstrate that the proposed hybrid MAC scheme is effective in decreasing packet delay and significantly shortens the length of the queue. The thesis continues with the discussion of the analytical model for the hybrid Token CDMA protocol. The proposed MAC scheme is analytically modelled as a multiserver multiqueue (MSMQ) system with a gated service discipline. The analytical model is categorized into three sections viz. the vacation model, the input model and the buffer model. The throughput and delay performance are then computed and shown to closely match the simulation results. Lastly, cross-layer optimization between the physical (PHY) and MAC layers for the hybrid token-CDMA scheme is discussed. The proposed joint PHY -MAC approach is based on the interaction between the two layers in order to enable the stations to dynamically adjust the transmission parameters resulting in reduced mutual interference and optimum system performance