Dynamic Performance of Electrical Balance Duplexing in a Vehicular Scenario

Electrical Balance Duplexer Field Trials in High-Speed Rail Scenarios

“…The simulation assumes a symmetrical, lossless hybrid junction, and ideal continuously variable lumped element components in the tunable balancing impedance circuit, and calculates the mean Tx-Rx isolation across a 20 MHz band as a function of time 2 . This EBD circuit simulation is identical to the simulations presented previously in [10]- [12], allowing for direct comparison of results. A more comprehensive description of the EBD simulation can also be found in these references.…”

“…A more comprehensive description of the EBD simulation can also be found in these references. As was the case in [10]- [12], the simulation implements three balancing impedance adaptation characteristics: ideal balancing, where the balancing impedance always takes on the optimal value, static balancing, where the balancing impedance is not dynamically adjusted to track antenna impedance changes, and limited rate adaptation (LRA), where the balancing impedance is updated at a given interval, thus allowing the trade-off between EBD re-balancing rate and Tx-Rx isolation to be observed. The duration of the simulations is approximately 2 s, this being determined by the time taken for a train to pass.…”

“…Previous contributions on this topic have combined EBD circuit simulations with antenna reflection coefficient measurements from dynamic environments to investigate adaptation requirements in handheld [10], indoor [11], and road vehicle scenarios [12]. Results demonstrated that antenna impedance tracking was critical in the user interaction scenario, requiring the EBD to be rebalanced at intervals of the order of 10 ms to maintain isolation, but adaptation was not essential in the indoor and road environments, due to the larger separation between the antenna and the reflecting objects [11], [12].…”

“…Results demonstrated that antenna impedance tracking was critical in the user interaction scenario, requiring the EBD to be rebalanced at intervals of the order of 10 ms to maintain isolation, but adaptation was not essential in the indoor and road environments, due to the larger separation between the antenna and the reflecting objects [11], [12].…”

“…Due to close proximity of passing trains and trackside infrastructure, a rail scenario has the potential to cause more substantial variation in the antenna impedance compared to the road scenario, and warrants investigation into the variation in Tx-Rx isolation and balancing impedance adaptation requirements in this scenario. The analysis methodology from [10]- [12], in which measured antenna dynamics are embedded into EBD circuit simulations, has been repeated for a high speed rail scenario. Furthermore, this paper also presents a hardware EBD with real time balancing impedance tracking, and demonstrates measured dynamic EBD performance in the high speed rail application.…”