English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

In this paper, we investigate the problem of pilot optimization and channelestimation of two-way relaying network (TWRN) aided by an intelligentreflecting surface (IRS) with finite discrete phase shifters. In a TWRN, thereexists a challenging problem that the two cascading channels fromsource-to-IRS-to-Relay and destination-to-IRS-to-relay interfere with eachother. Via designing the initial phase shifts of IRS and pilot pattern, the twocascading channels are separated by using simple arithmetic operations likeaddition and subtraction. Then, the least-squares estimator is adopted toestimate the two cascading channels and two direct channels from source torelay and destination to relay. The corresponding mean square errors (MSE) ofchannel estimators are derived. By minimizing MSE, the optimal phase shiftmatrix of IRS is proved. Then, two special matrices Hadamard and discreteFourier transform (DFT) matrix is shown to be two optimal training matrices forIRS. Furthermore, the IRS with discrete finite phase shifters is taken intoaccount. Using theoretical derivation and numerical simulations, we find that3-4 bits phase shifters are sufficient for IRS to achieve a negligible MSEperformance loss. More importantly, the Hadamard matrix requires only one-bitphase shifters to achieve the optimal MSE performance while the DFT matrixrequires at least three or four bits to achieve the same performance. Thus, theHadamard matrix is a perfect choice for channel estimation using low-resolutionphase-shifting IRS.

Pilot Optimization and Channel Estimation for Two-way Relaying Network Aided by IRS with Finite Discrete Phase Shifters