MOCZ for Blind Short-Packet Communication: Practical Aspects

We investigate practical aspects of a recently introduced blind (noncoherent) communication scheme, called modulation on conjugate-reciprocal zeros (MOCZ). MOCZ is suitable for a reliable transmission of sporadic and short-packets at ultra-low latency and high spectral efficiency via unknown multipath channels, which are assumed to be static over the receive duration of one packet. The information is modulated on the zeros of the transmitted discrete-time baseband signal’s z− transform. Because of ubiquitous impairments between the transmitter and receiver clocks, a carrier frequency offset occurs after down-conversion to the baseband. This results in a common rotation of the zeros. To identify fractional rotations of the base angle in the zero-pattern, we propose an oversampled direct zero-testing decoder to identify the most likely one. Integer rotations correspond to cyclic shifts of the binary message, which we determine by cyclically permutable codes (CPC). Additionally, the embedding of CPCs into cyclic codes, enables additive error-correction which reduces the bit-error-rate tremendously. Furthermore, we exploit the trident structure in the signal’s autocorrelation for an energy based detector to estimate timing offsets and the effective channel delay spread. We finally demonstrate how this joint data and channel estimation can be largely improved by receive antenna diversity at low SNR

MOCZ for Blind Short-Packet Communication: Practical Aspects

We investigate practical aspects of a recently introduced blind (noncoherent) communication scheme, called modulation on conjugate-reciprocal zeros (MOCZ). MOCZ is suitable for a reliable transmission of sporadic and short-packets at ultra-low latency and high spectral efficiency via unknown multipath channels, which are assumed to be static over the receive duration of one packet. The information is modulated on the zeros of the transmitted discrete-time baseband signal’s z− transform. Because of ubiquitous impairments between the transmitter and receiver clocks, a carrier frequency offset occurs after down-conversion to the baseband. This results in a common rotation of the zeros. To identify fractional rotations of the base angle in the zero-pattern, we propose an oversampled direct zero-testing decoder to identify the most likely one. Integer rotations correspond to cyclic shifts of the binary message, which we determine by cyclically permutable codes (CPC). Additionally, the embedding of CPCs into cyclic codes, enables additive error-correction which reduces the bit-error-rate tremendously. Furthermore, we exploit the trident structure in the signal’s autocorrelation for an energy based detector to estimate timing offsets and the effective channel delay spread. We finally demonstrate how this joint data and channel estimation can be largely improved by receive antenna diversity at low SNR

Noncoherent Short-Packet Communication via Modulation on Conjugated Zeros

We introduce a novel blind (noncoherent) communication scheme, called modulation on conjugate-reciprocal zeros (MOCZ), to reliably transmit short binary packets over unknown finite impulse response systems as used, for example, to model underspread wireless multipath channels. In MOCZ, the information is modulated onto the zeros of the transmitted signals z−transform. In the absence of additive noise, the zero structure of the signal is perfectly preserved at the receiver, no matter what the channel impulse response (CIR) is. Furthermore, by a proper selection of the zeros, we show that MOCZ is not only invariant to the CIR, but also robust against additive noise. Starting with the maximum-likelihood estimator, we define a low complexity and reliable decoder and compare it to various state-of-the art noncoherent schemes

Implementation Huffman algorithm modification using neuronal networks

En este trabajo se implementa un algoritmo de compresión, para ser utilizado en el proceso de codificación de la fuente de información en un sistema de telecomunicaciones. Esta implementación incluye una modificación en la estructura de datos manejada por el algoritmo de Huffman, que de forma canónica utiliza una estructura de datos abstractos tipo árbol binario para distribuir los caracteres o símbolos de la ráfaga de información a codificar, clasificándolos, dependiendo de las frecuencias relativas de aparición. Este árbol puede ser reemplazado por una red neuronal que es similar en su topología a un grafo k-completo dirigido, con pesos en las conexiones o aristas, de esta manera se logra entrenar la red neuronal para que encuentre patrones en las ráfagas de información acotadas en tamaño, fragmentando el mensaje y así aumentar la tasa de compresión de la información que se quiere enviar hacia el canal, este resultado también estará enmarcado en el análisis de la complejidad temporal que requiere el algoritmo para ser ejecutado; si se logra reducir el volumen de información, significaría una mejora en el grado de servicio y desempeño de la red de telecomunicaciones aumentando la capacidad sin depender del tipo de canal ni de su ancho de banda.In this work a compression algorithm is implemented, to be used in the process of coding the source of information in a telecommunications system. This implementation includes a modification in the data structure managed by the Huffman algorithm, which canonically uses a binary tree abstract data structure to distribute the characters or symbols of the information burst to be encoded, classifying them, depending on the frequencies relative of appearance. This tree can be replaced by a neural network that is similar in its topology to a directed k-complete graph, with weights in the connections or edges, in this way it is possible to train the neural network so that it finds patterns in the limited bursts of information in size, fragmenting the message and thus increasing the compression rate of the information to be sent to the channel, this result will also be framed in the analysis of the temporal complexity required by the algorithm to be executed; If it is possible to reduce the volume of information, it would mean an improvement in the degree of service and performance of the telecommunications network by increasing capacity without depending on the type of channel or its bandwidth