Secure ranging refers to the capability of upper-bounding the actual physical distance between two devices with reliability. This is essential in a variety of applications, including to unlock physical systems. In this work, we will look at secure ranging in the context of ultra-wideband impulse radio (UWB-IR) as specified in IEEE 802.15.4z (a.k.a. 4z). In particular, an encrypted waveform, i.e. the scrambled timestamp sequence (STS), is defined in the high rate pulse repetition frequency (HRP) mode of operation in 4z for secure ranging. This work demonstrates the security analysis of 4z HRP when implemented with an adequate receiver design and shows the STS waveform can enable secure ranging. We first review the STS receivers adopted in previous studies and analyze their security vulnerabilities. Then we present a reference STS receiver and prove that secure ranging can be achieved by employing the STS waveform in 4z HRP. The performance bounds of the reference secure STS receiver are also characterized. Numerical experiments corroborate the analyses and demonstrate the security of the reference STS receiver.

It is well-known that opportunistic transmission schemes are sum-capacity optimal, in the Shannon sense, for symmetric cellular networks with single-antenna transceivers. However, for a practical system operating at non-negligible error probability, the correctly delivered throughput (or spectral efficiency) is a more useful figure-of-merit. In this paper, we present a mathematical model for the average throughput of a practical wireless system with channel-aware user scheduling in a symmetric Rayleigh fading cellular system. By employing an accurate model for the block error probability with turbo coding, and accounting for channel estimation errors, channel feedback quantization, and feedback delay, we present closed-form expressions for the average spectral efficiency of the downlink scheduler.

We consider a team of miniature unmanned air vehicles (MUAVs) in a multi-static radar scenario. Time delay and Doppler measurements made at the UAVs are transmitted to a base station which is tracking a target. The base then transmits heading commands to the MUAVs to reduce the tracking error. Optimal solutions that attempt to minimize a function of the error covariance or maximize the observability of the system are computationally difficult to implement. We present a simpler approximate method that yields a closed-form solution and performs comparably to the optimal approaches.