This paper focuses on the performance of LoRa systems after channel decoding. First, we introduce a matrix model for the coded transmission and reception of LoRa signals. Second, we theoretically evaluate the probability of bit error of coherently and noncoherently detected LoRa signals, in additive white Gaussian noise (AWGN), also assuming hard decoding of the LoRa physical layer Hamming code. Simulation results confirm the correctness of the theoretical expressions. Third, we analyze by simulation the coded performance of LoRa systems, with both hard and soft decoding, assuming a multipath channel model already used in the literature. Our analysis quantifies the performance gain of channel coding with respect to uncoded transmissions, in both AWGN and multipath channels, under the assumption that the coded system uses the same bandwidth with lower bit rate.

In this paper we present a technique that can be used for optimizing the streaming of Motion JPEG 2000 video when the communication channel can be abstracted as a binary symmetric channel (BSC), characterized by a certain slowly variable rate of transmission errors. The video is packetized and every packet is protected with a Reed-Solomon forward error correction (FEC) code and then sent on the communication channel. The FEC helps to recover from erased/error-affected source information bytes at the receiver-decoder. The optimized amount of error protection is chosen by using an uncomplicated mathematical expression, given the knowledge of the channel status. In particular, we show the results of simulations that outline the robustness of this technique and its clear advantage over more trivial solutions.

In this paper, we present a theoretical method to find an optimal source and channel code allocation, by considering an embedded image compression standard such as JPEG 2000 and a memoryless transmission channel. Lagrangian optimization is used to find an optimal error correction profile, from a PSNR perspective, starting from intermediate rate-distortion traces. The resulting mathematical relationship is simple and can be computed in real time. Simulations on a binary symmetric channel show that the achieved performance, in terms of PSNR, is comparable with that of similar methods reported in literature, while keeping a lower complexity.

In this paper we present a novel implementation of the JPWL standard on a DSP device, targeted to the protection of HD video streams at 50 Mbit/s. Several investigations on computational cost have been carried out in order to find the parts that had to be optimized for DSP. The result is an implementation that uses tailored instructions for operation on Galois Field and Enhanced Direct Memory Access (EDMA) for interleaving.

The transmission of JPEG 2000 images or video over wireless channels has to cope with the high probability and burstyness of errors introduced by Gaussian noise, linear distortions, and fading. At the receiver side, there is distortion due to the compression performed at the sender side, and to the errors introduced in the data stream by the channel. Progressive source coding can also be successfully exploited to protect different portions of the data stream with different channel code rates, based upon the relative importance that each portion has on the reconstructed image. Unequal Error Protection (UEP) schemes are generally adopted, which offer a close to the optimal solution. In this paper, we present a dichotomic technique for searching the optimal UEP strategy, which lends ideas from existing algorithms, for the transmission of JPEG 2000 images and video over a wireless channel. Moreover, we also adopt a method of virtual interleaving to be used for the transmission of high bit rate streams over packet loss channels, guaranteeing a large PSNR advantage over a plain transmission scheme. These two protection strategies can also be combined to maximize the error correction capabilities.

In this paper, we present an overview of the JPWL standardization activity. JPWL is an extension of JPEG 2000 for the efficient transmission of JPEG 2000 images over an error-prone wireless network. More specifically, JPWL supports a set of tools for error protection and correction, including forward error correcting codes (FEC), unequal error protection (UEP), data partitioning and interleaving

This paper analyses the performance of orthogonal multicarrier DS-CDMA systems for personal communications. The basic system operates using the orthogonal multicarrier technique combined with direct sequence code division multiple access. The non-stationary behaviour of the channel is tracked by a periodic sounding. This technique leads to relatively simple receivers that can be implemented with current VLSI and DSP technology. Taking into account the challenges related to an up-link implementation, the system performance in the down-link is investigated both for synchronous and asynchronous DS-CDMAs. In particular, the schemes which work with Walsh sequences (in the synchronous case) are compared with the schemes operating by binary Gold sequences and 4-phase near-optimal sequences (in the asynchronous case). The comparison is carried out on the basis of significant parameters such as bit error rate, spectral efficiency and multipath counteraction for different system configurations.

This paper presents an analysis of the performances of a digital mobile radio link based on DS-CDMA technique and the RAKE receiver. The adopted signature sequences are complex and characterized by different correlation properties, that lead to different performances in terms of bit error rate and spectral efficiency. Moreover, a preliminary analysis of the performances under non-linear channel behaviour and different modulation schemes is provided.>