Harm S. Cronie

Lossless source coding with polar codes

In this paper lossless compression with polar codes is considered. A polar encoding algorithm is developed and a method to design the code and compute the average compression rate for finite lengths is given. It is shown that the scheme achieves the optimal compression rate asymptotically. Furthermore, the proposed scheme has a very good performance at finite lengths. Both the encoding and decoding operations can be accomplished with complexity O(N log N) where N denotes the length of the code.

Superposition Coding for Power-and Bandwidth Efficient Communication over the Gaussian Channel

A method for power- and bandwidth efficient communication over the Gaussian channel is presented. The method is based on the superposition of binary random variables. As an example we design a signal constellation for a spectral efficiency of 10 bit/s/Hz. The constellation has a constrained capacity limit only 0.18 dB from the Gaussian capacity limit. Moreover, we show that combined with multi-level coding and low-density parity-check codes, a low bit-error rate is achieved at 0.6 dB from the Gaussian capacity limit for a large codeword length.

26.3 A pin- and power-efficient low-latency 8-to-12Gb/s/wire 8b8w-coded SerDes link for high-loss channels in 40nm technology

The continuing demand for higher bandwidth in serial interconnects has pushed the symbol rate of differential lanes into the high-insertion-loss region of channels. Multi-level signaling such as differential PAM-4 [1] has been used to mitigate the loss of electrical channels by lowering the signal spectrum. Such an approach suffers from lower SNR tolerance as well as higher susceptibility to crosstalk and ISI as compared to differential signaling (DS). Coded differential approaches have been reported [2] to mitigate ISI. Our approach is a generalization of DS in which ternary values are transmitted on an 8-wire bus. The set of transmitted values belongs to a code consisting of 256 code-words called the 8b8w-code (8-bits-on-8-wires) [3]. The specific correlations in the code-words of the 8b8w-code eliminate transmit common-mode and simultaneous switching output (SSO) noise and allow for detection via self-referencing comparators (unlike PAM-4), which provides additional noise immunity. Compared to DS, the 8b8w-code offers twice the throughput at 50% of the line power. Compared to PAM-4, the code offers better SNR (3dB) at 38% of the line power with enhanced tolerance of ISI and lower crosstalk generation. The design and experimental verification of an 8b8w transceiver in 40nm CMOS is described. Transmission is achieved up to 12Gb/s per wire over 55cm of Rogers with up to 15dB loss.

Decoding algorithms for binary Raptor codes over nonbinary channels

In this paper, we introduce a class of decoding algorithms for binary Raptor codes used for transmission over q-ary channels, where q = 2m. The algorithms provide a tradeoff between complexity and decoding capability. Whereas the running time of the q-ary belief-propagation algorithms is m2m times that of its binary counterpart, in our case the complexity factor can be chosen between m and 2m, depending on the error-correction capability required. As such, the running time can be much better than the q-ary belief-propagation algorithm. The main idea behind our algorithm is to apply an appropriate set of GF(2)-linear forms of GF(q) to the Raptor code to obtain a set of binary codes which can be decoded independently in parallel. After a prescribed number of iterations, for each of the input symbols of the Raptor code and each of the linear forms an estimate is obtained on the probability that this linear form applied to the input symbol is zero. By gathering these probabilities and performing a maximum-likelihood decoding on a suitable code of very small blocklength, we are able to obtain a good estimate of the value of the input symbol. Simulations results are provided for a families of q-ary symmetric channels and non-symmetric channels which show the performance of our decoding algorithms.

RF Performance of T-DAB Receivers

In every wireless system, the weakest link determines the performance of the network. In this paper the Radio Frequency (RF) performance of both band III and L-band Terrestrial Digital Audio Broadcasting (T-DAB) consumer receivers are discussed. The receivers have been tested based on the EN 50248 standard. The test results show that the average consumer receiver for band III meets the requirements set by EN 50248, except for the non-adjacent interferer experiments. In this experiment, the average consumer receiver performs up to 10 dB worse than required. In addition, the experiments reveal that there is a large difference in performance between consumer receivers. Besides band III, also L-band consumer receivers have been evaluated. The results of the L-band experiments show that the consumer receivers are not capable of decoding a DAB signal with a COST207 rural area channel model in case of T-DAB mode IV. Network operators should for this reason use mode II for the L-band and should expect a larger influence of non-adjacent interference on receiver performance in band III than anticipated based on EN 50248.