Turbo Detection of Space-time Trellis-Coded Constant Bit Rate Vector-Quantised Videophone System using Reversible Variable-Length Codes, Convolutional Codes and Turbo Codes

In this treatise we characterise the achievable performance of a proprietary video transmission system, which employs a Constant Bit Rate (CBR) video codec that is concatenated with one of three error correction codecs, namely a Reversible Variable-Length Code (RVLC), a Convolutional Code (CC) or a convolutional-based Turbo Code (TC). In our investigations, the CBR video codec was invoked in conjunction with Space-Time Trellis Coding (STTC) designed for transmission over a dispersive Rayleigh fading channel. At the receiver, the channel equaliser, the STTC decoder and the RVLC, CC or TC decoder, as appropriate, employ the Max-Log Maximum A-Posteriori (MAP) algorithm and their operations are performed in an iterative 'turbo-detection' fashion. The systems were designed for maintaining similar error-free video reconstruction qualities, which were found to be subjectively pleasing at a Peak Signal to Noise Ratio (PSNR) of 30.6~dB, at a similar decoding complexity per decoding iteration. These design criteria were achieved by employing differing transmission rates, with the CC- and TC-based systems having a 22% higher bandwidth requirement. The results demonstrated that the TC-, RVLC- and CC-based systems achieve acceptable subjective reconstructed video quality associated with an average PSNR in excess of 30~dB for $E_b/N_0$ values above 4.6~dB, 6.4~dB and 7.7~dB, respectively. The design choice between the TC- and RVLC-based systems constitutes a trade-off between the increased error resilience of the TC-based scheme and the reduced bandwidth requirement of the RVLC-based scheme

Practical Resource Allocation Algorithms for QoS in OFDMA-based Wireless Systems

In this work we propose an efficient resource allocation algorithm for OFDMA based wireless systems supporting heterogeneous traffic. The proposed algorithm provides proportionally fairness to data users and short term rate guarantees to real-time users. Based on the QoS requirements, buffer occupancy and channel conditions, we propose a scheme for rate requirement determination for delay constrained sessions. Then we formulate and solve the proportional fair rate allocation problem subject to those rate requirements and power/bandwidth constraints. Simulations results show that the proposed algorithm provides significant improvement with respect to the benchmark algorithm.Comment: To be presented at 2nd IEEE International Broadband Wireless Access Workshop. Las Vegas, Nevada USA Jan 12 200

Downlink Video Streaming for Users Non-Equidistant from Base Station

We consider multiuser video transmission for users that are non-equidistantly positioned from base station. We propose a greedy algorithm for video streaming in a wireless system with capacity achieving channel coding, that implements the cross-layer principle by partially separating the physical and the application layer. In such a system the parameters at the physical layer are dependent on the packet length and the conditions in the wireless channel and the parameters at the application layer are dependent on the reduction of the expected distortion assuming no packet errors in the system. We also address the fairness in the multiuser video system with non-equidistantly positioned users. Our fairness algorithm is based on modified opportunistic round robin scheduling. We evaluate the performance of the proposed algorithms by simulating the transmission of H.264/AVC video signals in a TDMA wireless system

Wireless Video Transmission with Over-the-Air Packet Mixing

In this paper, we propose a system for wireless video transmission with a wireless physical layer (PHY) that supports cooperative forwarding of interfered/superimposed packets. Our system model considers multiple and independent unicast transmissions between network nodes while a number of them serve as relays of the interfered/superimposed signals. For this new PHY the average transmission rate that each node can achieve is estimated first. Next, we formulate a utility optimization framework for the video transmission problem and we show that it can be simplified due to the features of the new PHY. Simulation results reveal the system operating regions for which superimposing wireless packets is a better choice than a typical cooperative PHY.Comment: 2012 Packet Video Worksho

Scalable video/image transmission using rate compatible PUM turbo codes

The robust delivery of video over emerging wireless networks poses many challenges due to the heterogeneity of access networks, the variations in streaming devices, and the expected variations in network conditions caused by interference and coexistence. The proposed approach exploits the joint optimization of a wavelet-based scalable video/image coding framework and a forward error correction method based on PUM turbo codes. The scheme minimizes the reconstructed image/video distortion at the decoder subject to a constraint on the overall transmission bitrate budget. The minimization is achieved by exploiting the rate optimization technique and the statistics of the transmission channel