November 13, 2017

Physical limits on directional beam performance of 28 GHz links

  • Chizhik D.
  • Valenzuela R.
  • Venkatesan S.

Impact of finite coherence in frequency and time on directional beam in a canonical 28 GHz small cell link is assessed. Terminal motion and delay spread are found to limit the maximum achievable directional gain due to the need to measure the channel across time and frequency. It is found that pedestrian speeds (1m/s) still allow 1 Gbps rate at 100 m in Non-Line-of-Sight (25 dB shadow) link using 32 array elements in 300 MHz bandwidth, nearly 10x the rate of a 10 MHz-wide cellular link at 2 GHz. Vehicular speed of 30 m/s requires nearly 2x the element count to reach the same rate.

View Original Article

Recent Publications

January 01, 2018

Fair Dynamic Spectrum Management for QRD-Based Precoding with User Encoding Ordering in Downstream Transmission

In next generation DSL networks such as, employing discrete multi-tone transmission in high frequencies up to 212 MHz, the crosstalk among lines reaches very high levels. To precompensate the crosstalk in downstream transmission, QRD-based precoding has been proposed as a near-optimal dynamic spectrum management (DSM) technique. However, the performance ...

January 01, 2018

Practical Mitigation of Passive Intermodulation in Microstrip Circuits

This paper presents new experimental evidence and a novel practical approach for mitigation of passive intermodulation (PIM) in microstrip circuits fabricated on commercial printed circuit board laminates. The mechanisms of distributed PIM in microstrip circuits are reviewed and a phenomenology of PIM generation due to locally enhanced electromagnetic fields at ...

January 01, 2018

Efficient Cooperative HARQ for Multi-Source Multi-Relay Wireless Networks

In this paper, we compare the performance of three different cooperative Hybrid Automatic Repeat reQuest (HARQ) protocols for slow-fading half-duplex orthogonal multiple access multiple relay channel. Channel State Information (CSI) is available at the receiving side of each link only. Time Division Multiplexing is assumed, where each orthogonal transmission occurs ...