Video data claims a significant portion of global mobile data communications, currently standing at 55%. This demand outburst has been due to exceptional display technolo- gies, on-demand video, gaming and live video ...
详细信息
Video data claims a significant portion of global mobile data communications, currently standing at 55%. This demand outburst has been due to exceptional display technolo- gies, on-demand video, gaming and live video streaming, to name a few. Despite the massive data rates supported by modern mobile communication technologies, video data is starting to overload mobile networks. This is particularly true in links with low connectivity, where repeat requests flood the system. As solutions for this inevitable demand growth, in addition to efficient video compres- sion methods, more video data error resilience must be sought. One reason video traffic is vulnerable to channel errors is the method it is treated at transmission; treatment as any other generic data type. Video is a unique data type because its ultimate user is not a machine, but a human, and because the contents within the data are inter- dependent on each other. Based on its properties, video compression, transmission methodology, and the decoding function must be adapted. By considering video com- munication as a collaborative effort of these three functions, error resilience can be effectively implemented. Analysis of radio resources available for data transmission in a multipath fading channel reveals that some resources are more robust than others. In the first contribution of this thesis, this characteristic is utilised to impose more resilience to more sensitive data within the video. Reliable means of forecasting the relative robustness of each radio resource are designed. Criteria for identifying the sensitivity of different video data segments are formulated. Finally, a technology is presented to map data to radio resources such that maximum received video quality is achieved. While the focus on the first contribution was on harmonising the transmission methods with the features of the compressed video payload, the second contribution takes an alternative route to error resilience by focusing on t
Cílem bakalářské práce Zpracování signálů v systému Flarion bylo prostudovat způsoby zpracování signálu ve fyzické vrstvě a architekturu sítě Flarion....
详细信息
Cílem bakalářské práce Zpracování signálů v systému Flarion bylo prostudovat způsoby zpracování signálu ve fyzické vrstvě a architekturu sítě Flarion. Na základě získaných poznatků při studiu fyzické vrstvy bylo za úkolem sestavit v prostředí Matlab model systému a simulace BER v závislosti na poměr vysílaného výkonu a výkonu rušivého signálu. V první části práce je detailní popis fyzické vrstvy Flarionu, probrána je baseband a OFDM modulace, ldpc kódování a frekvenční skákání. V druhém části práce je prostudována architektura sítě, ekvalizace, řízení výkonu, radiových zdrojů, a způsob handoffu. Ve třetí části práce je vytvoření downlink a uplink modelu v Matlab, dále je provedena simulace BER v závislosti na poměr vysílaného výkonu a výkonu rušivého signálu.
In this paper, we propose a hybrid multidimensional coded-modulation (CM) scheme based on a new multidimensional signal constellation design as a solution to limited bandwidth and high energy consumption of informatio...
详细信息
In this paper, we propose a hybrid multidimensional coded-modulation (CM) scheme based on a new multidimensional signal constellation design as a solution to limited bandwidth and high energy consumption of information infrastructure. This multidimensional signal constellation, herewith called vector-quantization-based signal constellation design (VQ-SCD), is based on the vector quantization theory. The proposed scheme employs both the electrical basis functions (in the form of the prolate spheroidal wave functions) and the optical basis functions (in the form of polarization and spatial mode states) as optical basis functions. The proposed coded VQ-SCD scheme is the enabling technology for optical serial transport with bit rates exceeding 1000 Tb/s (1 Pb/s). In addition, the CM scheme we proposed allows for the adaptive, elastic, and dynamic allocation of the bandwidth. This fine granularity bandwidth manipulation is envisioned as a part of future software-defined optical networking.
For satellite communication with bi-directional channels, we investigate the application of Low-Density Parity-Check (ldpc) coding by incorporating channel state information (CSI) to enhance its security performance. ...
详细信息
For satellite communication with bi-directional channels, we investigate the application of Low-Density Parity-Check (ldpc) coding by incorporating channel state information (CSI) to enhance its security performance. Specifically, the scheme includes two main steps: CSI measurement and the design of ldpc security coding. Based on its reciprocity and uniqueness, CSI is first obtained by estimating bidirectional channels followed with quantization and reconciliation, which results in the binary sequence of the CSI. In this work, based on the characteristics of satellite communication, the extended irregular repeat-accumulate (eIRA) of ldpc codes were adapted in order to reduce the storage capacity and computational complexity. Finally, LPDC secure coding scheme utilizes a scrambling matrix that is converted from the CSI's binary sequence to complete the ldpc coding process. Based on NI USRP 2920, a simulation platform was developed to study the performance of the proposed scheme. The evaluation results show that our proposed scheme can improve the reliability of received information for the legitimate receivers, while leading to increased bit error rates for the eavesdroppers, and thus enhance the communication security.
To find the minimum distance computation of ldpc codes is a NP problem,there has been no simple way to obtain the minimum distance of ldpc codes because of the code length being very *** provide a solution to deal wit...
详细信息
To find the minimum distance computation of ldpc codes is a NP problem,there has been no simple way to obtain the minimum distance of ldpc codes because of the code length being very *** provide a solution to deal with this hard problem,this paper develops an algorithm to estimate the weights and distance of ldpc codes based on generator *** paper establishes the upper bounds of weights and distances of ldpc codes by using the vectors of generator matrices,which is different from the existed probabilitistic search methods for the weights' and distances of LCPC *** proposed algorithm can greatly reduce the searching time of weights and *** the algorithm we can obtain some ldpc codes of great distances and being free girth *** verify the algorithms to be valid.
We propose a new strategy for cooperative transmit diversity based on physical layer network coding and multiuser detection. Physical-layer Network coding (PNC) exploits interference, instead of avoiding it, all sourc...
详细信息
We propose a new strategy for cooperative transmit diversity based on physical layer network coding and multiuser detection. Physical-layer Network coding (PNC) exploits interference, instead of avoiding it, all source nodes transmit simultaneously to significantly enhance network throughput. The scenario under consideration is one in which two source nodes A and B transmit information to a common destination node D. Simulation results show that our new scheme outperforms traditional cooperative diversity based on decode-and-forward about 1.5 dB in terms of frame-error-rate (FER) but less complexity.
暂无评论