# Secure Transmission of Delay-Sensitive Data over Wireless Fading Channels

## TL;DR

This paper analyzes the throughput and energy efficiency of secure, delay-sensitive wireless data transmission over fading channels, considering buffer constraints, source characteristics, and secrecy requirements.

## Contribution

It introduces a comprehensive framework combining effective capacity, bandwidth, and secrecy capacity to evaluate secure transmission performance under QoS constraints.

## Key findings

- Minimum energy per bit for reliable secure communication is characterized.
- Buffer/delay constraints significantly impact throughput and energy efficiency.
- Channel correlation and knowledge influence secure transmission performance.

## Abstract

In this paper, throughput and energy efficiency of secure wireless transmission of delay sensitive data generated by random sources is studied. A fading broadcast model in which the transmitter sends confidential and common messages to two receivers is considered. It is assumed that the common and confidential data, generated from Markovian sources, is stored in buffers prior to transmission, and the transmitter operates under constraints on buffer/delay violation probability. Under such statistical quality of service (QoS) constraints, effective capacity of time-varying wireless transmissions and effective bandwidth of Markovian sources are employed to determine the throughput. In particular, secrecy capacity is used to describe the service rate of buffers containing confidential messages. Moreover, energy per bit is used as the energy efficiency metric and energy efficiency is studied in the low signal-to-noise (SNR) regime. Specifically, minimum energy per bit required for the reliable communication of common and confidential messages is determined and wideband slope expressions are identified. The impact of buffer/delay constraints, correlation between channels, source characteristics/burstiness, channel knowledge at the transmitter, power allocation, and secrecy requirements on the throughput and energy efficiency of common and confidential message transmissions is identified.