Guest editorial for the special issue on software-defined radio transceivers and circuits for 5G wireless communications

Yichuang Sun, Baoyong Chi, and Heng Zhang, Guest Editorial for the Special Issue on Software-Defined Radio Transceivers and Circuits for 5G Wireless Communications, published in IEEEE Transactions on Circuits and Systems II: Express Briefs, Vol. 63 (1): 1-3, January 2016, doi: https://doi.org/10.1109/TCSII.2015.2506979.Peer reviewedFinal Accepted Versio

Fundamental Efficiency Limit of Passive Non-Magnetic Self-Interference Suppression in Full-Duplex Radios

Passive non-magnetic self-interference suppression circuits are currently used as first stages of complex full-duplex radio systems that allow simultaneous reception and transmission within the same channel. This paper introduces the upper efficiency limit for such circuitry. It is demonstrated that for these devices it is not feasible to have simultaneously high efficiency, good transmitter-to-receiver isolation and same propagation channel for transmission and reception. More specifically, the maximum efficiency for most typical case cannot exceed 50% if good isolation is obtained

Passive Self-Interference Suppression for Single Channel Full-Duplex Operation

Full duplex radios have become a topic of increased interest in the wireless communications community. As part of this development, many efforts were directed to passively decrease the self-interference level at the antenna outputs. However, in many proposed solutions transmission and reception occur through different propagation channels. This paper demonstrates and quantifies the negative impact of channel differentiation on pivotal applications of full-duplex radio, such as cognitive radio. Antenna designs used for self-interference suppression in full-duplex radio architectures are analyzed. In order to ensure that transmission and reception occur within the same propagation channel, the use of the envelope correlation coefficient is proposed. The paper aims to firstly define the problem and proposes a metric to quantitatively assess full-duplex antenna designs. This is followed by analysis and discussion of representative full-duplex solutions (i.e. their antenna and passive RF feed components) proposed in the literature. Finally, it is demonstrated for the first time, that the passive non-magnetic self-interference suppression comes at the cost of increased losses in the structure. A theoretical upper limit for the antenna efficiency is proposed. Its consistency is verified for three representative full-duplex antenna designs which are highly documented in the literature