This paper discusses the application of Analog Joint Source Channel Coding (JSCC) to Non-Linear Channels, including underwater acoustic channels. Different from traditional digital communication systems, which utilize a source code followed by a channel code, Analog JSCC systems perform coding via a single mapping. We will focus on a particular class of analog codes called space filling curves. The underwater acoustic channel is typically non-linear with Inter-Symbol Interference (ISI). We will first study a simplified version assuming no ISI, developing a scheme to adapt space filling curves to this environment, and studying the theoretical limits. Then, we will extend the analysis to the end-to-end acoustic channel (including ISI), discussing the proposed system in this case. Finally, we will present simulation results of the proposed communication system for the simplified (no ISI) and end-to-end channels.

We address the evaluation of low-complexity analog Joint Source Channel Coding (JSCC) methods for the transmission of discrete-time analog symbols over Multiple-Input Multiple-Output (MIMO) Multiple Access Channels (MAC). Analog JSCC is employed to encode the source information at each transmitter prior to be directly input to the MAC access scheme. Three channel access methods are considered to ensure the receiver is able to recover the user information: Code Division Multiple Access (CDMA), linear MMSE access codes and opportunistic access. CDMA allows the orthogonal transmission of the user data requiring only Channel State Information (CSI) at reception. On the other hand, linear MMSE access codes exploit CSI knowledge at transmission and exhibit better performance. Finally, opportunistic access also exploits CSI at transmission and allocates all MAC resources to the user with the strongest channel. This latter access scheme exhibits the best performance in terms of sum distortion although it may lead to unfair rate distributions among users.

We address the transmission of discrete-time analog samples over a block fading Multiple Access Channel (MAC). We propose two practical access schemes to achieve the sum capacity of a MAC channel: opportunistic and Code Division Multiple Access (CDMA). The first one is optimal when the Channel State Information (CSI) from all users is available at all the transmitters. However, it can lead to an unfair distribution of the power and transmission rate for each user. On the other hand, the CDMA access scheme allows setting individual rate constraints while showing excellent performance when transmitting either uncompressed or compressed analog Gaussian samples.

We consider the problem of transmission of independent and correlated Gaussian sources over the two user Gaussian Broadcast Channel (GBC). We present a low complexity, low delay, analog joint source channel coding communication system based on extensions of existing Nested Quantization techniques. Simulations results show that the resulting performance is close to the optimal theoretical limits for several cases of interest.

We investigate the performance of analog joint source channel coding systems based on the use of spiral-like space filling curves for the transmission of Gaussian sources over non-linear channels. The non-linearity proceeds from a non-linear power amplifier in the transmitter that exhibits saturation effects at the extremes and also near the origin (see Figure below). Then, the output of the amplifier is sent through an AWGN channel which introduces attenuation that depends on the distance between the transmitter and the receiver. This means that the attenuation cannot be subsumed into the noise variance.