5 research outputs found
Channel Capacity Enhancement by Pattern Controlled Handset Antenna
This paper presents a radiation pattern controlled antenna for handset terminals to reduce the correlation coefficient between antennas and enhance the channel capacity in MIMO applications. A pair of small inverted-F shaped antennas combined by a phase shifter provides a single port with controlled pattern. To enhance the channel capacity, the phase difference for the IFA array is optimized using the evaluation parameter of reception level, correlation coefficient and mean effective gain of the proposed array geometry. The channel capacity enhancement is verified by assuming Croneker scattering under Nakagami-Rice propagation model
Integrated optical vortex beam receivers
A simple and ultra-compact integrated optical vortex beam receiver device is
presented. The device is based on the coupling between the optical vortex modes and
whispering gallery modes in a micro-ring resonator via embedded angular gratings, which
provides the selective reception of optical vortex modes with definitive total angular
momentum (summation of spin and orbital angular momentum) through the phase matching
condition in the coupling process. Experimental characterization confirms the correct
detection of the total angular momentum carried by the vortex beams incident on the device.
In addition, photonic spin-controlled unidirectional excitation of whispering-gallery modes in
the ring receiver is also observed, and utilized to differentiate between left- and right-circular
polarizations and therefore unambiguously identify the orbital angular momentum of incident
light. Such characteristics provide an effective mode-selective receiver for the eigen-modes in
orbital angular momentum fiber transmission where the circularly polarized OAM modes can
be used as data communications channels in multiplexed communications or as photonic
states in quantum information applications
MIMO Systems
In recent years, it was realized that the MIMO communication systems seems to be inevitable in accelerated evolution of high data rates applications due to their potential to dramatically increase the spectral efficiency and simultaneously sending individual information to the corresponding users in wireless systems. This book, intends to provide highlights of the current research topics in the field of MIMO system, to offer a snapshot of the recent advances and major issues faced today by the researchers in the MIMO related areas. The book is written by specialists working in universities and research centers all over the world to cover the fundamental principles and main advanced topics on high data rates wireless communications systems over MIMO channels. Moreover, the book has the advantage of providing a collection of applications that are completely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity