Massive multiple-input multiple-output (mMIMO) communications are one of the enabling technologies 5G and beyond networks. While prior work indicates that mMIMO networks employing time division duplexing have a significant capacity growth potential, deploying in frequency (FDD) remains problematic. The two main difficulties FDD scalability downlink reference signals overhead associated with req...

Between 81°30ʹE and 83°E, the Himalayan range's “perfect” arcuate shape is interrupted by an embayment. We hypothesize that thrust geometry duplexing along megathrust at midlower-crustal depths play a leading role in growth of embayment as well southern margin Tibetan plateau. To test this hypothesis, we conducted thermokinematic modeling published thermochronologic data from topographic struct...

In conventional multi-user multiple-input multiple-output (MU-MIMO) systems with frequency division duplexing (FDD), channel acquisition and precoder optimization processes have been designed separately although they are highly coupled. This paper studies an end-to-end design of downlink MU-MIMO which include pilot sequences, limited feedback, precoding. To address this problem, we propose a no...

We present a practical solution for dynamic spectrum management (DSM) in digital subscriber line systems: the normalized-rate iterative algorithm (NRIA). Supported by a novel optimization problem formulation, the NRIA is the only DSM algorithm that jointly addresses spectrum balancing for frequency division duplexing systems and power allocation for the users sharing a common cable bundle. With...

Systems that employ multiple antennas in both the transmitter and the receiver of a wireless system have been shown to promise extraordinary spectral efficiency. With full channel knowledge at the transmitter and receiver, Raleigh and Cioffi proposed a spatio-temporal coding scheme, discrete matrix multitone (DMMT), to achieve asymptotically optimum multiple-input–multiple-output (MIMO) channel...

This paper considers the uplink pilot overhead in a time division duplexing (TDD) massive Multiple Input Multiple Output (MIMO) mobile systems. A common scenario of conventional massive MIMO systems is a Base Station (BS) serving all user terminals (UTs) in the cell with the same TDD frame format that fits the coherence interval of the worst-case scenario of user mobility (e.g. a moving train w...

A unicasting Ad hoc network is considered, where each node i is equipped with a receive/transmit beamformer pair (wi,gi). Each node’s SNR Γi satis£es Γi ≥ γ0. It is £rst shown that the minimum sum power beamformers for the network satisfy a weak duality condition, in which the pairs (g i ,w ∗ i ) achieve the same sum power as the primal network. However, the optimum receive beamformer wi is not...

This paper is concerned with characterisation of passive intermodulation (PIM) in distributed RF circuits and components with the aid of emerging nonlinear RF techniques. Conventionally, intermodulation (IM) is defined as a phenomenon which is characterised by the appearance of additional spectral components in the output spectrum of a nonlinear system different from the carrier frequencies. Th...

Transmitter leakage is caused by limited isolation between Tx and Rx paths of an frequency-division duplexing (FDD) transceiver due to use of non-ideal duplexers. As the leakage can seriously impair the performance of the receiver, it is important to increase the isolation of the existing system. A portion of the leakage falling into the Rx band can’t be removed using conventional band-pass tec...

The energy efficiency has become more important in MIMO wireless communication system in recent days. The antennas at each end of the communications circuit are combined to minimize errors and optimize data speed. In Multiple Input Multiple Output Time Division Duplexing (MIMO TDD), by assuming reciprocity property the downlink transmission is based on uplink channel estimation. When more uplin...