This paper sets up a framework for designing a massive multiple-input multiple-output (MIMO) testbed by investigating hardware (HW) and system-level requirements such as processing complexity, duplexing mode and frame structure. Taking these into account, a generic system and processing partitioning is proposed which allows flexible scaling and processing distribution onto a multitude of physic...

Recent attention to resource allocation algorithms for multiservice CDMA networks has focused on algorithms optimizing the aggregate throughputs (sum of all individual throughputs) on the uplink and on the downlink. Unfortunately, for a given set of real time (RT) and non real-time (NRT) communications services, such optimal algorithms involve non-integer spreading factors that do not belong to...

We consider an uplink opportunistic cognitive radio network, operating in frequency division duplexing (FDD) mode and consisting of $N_{\mathrm {u}}$ secondary users (SUs) access point (AP), that can a spectrum band licensed to primar...

This paper provide a review of the active integrated antenna (AIA) technologies. After a brief introduction on the definition and some historical remarks, the paper concentrates on the research effort on the past decades or so. The AIAs are reviewed in its various functions. First, an oscillator-type AIA is presented, followed by very interesting aspects of coupled oscillator arrays for phase c...

• Massive MIMO prototype  64 Antenna array supported by 16 ExpressMIMO2 cards  Centralized high end computing engine • Massive MIMO key challenges  Acquisition of channel information at transmitter (CSIT);  Pilot contamination;  Fast and distributed coherent signal processing;  Hardware impairment, etc. • Time Division Duplexing (TDD)  Use TDD channel reciprocity for massive MIMO to ease...

We study the performance of a single-cell massive multiple-input multiple-output orthogonal frequency-division multiplexing (MIMO-OFDM) system that uses linear precoding to serve multiple users on the same time-frequency resource. To minimize overhead, the channel estimates at the base station are obtained via comb-type pilot tones during the training phase of a time-division duplexing system. ...

Adaptive duplexing eliminates the need for multiple switched duplexers in multiband systems. The technique is based on combining a low isolation device and an active double loop cancelling scheme. A duplexer provides attenuation to the main Tx signals entering the receiver and Tx noise corrupting the receiver band. The solution is tested on a direct conversion receiver and uses an adaptive oned...

In an Frequency-Division Duplexing (FDD) transceiver, a high power transmitted signal can leak into the RX chain due to limited isolation of a duplexer. Such signal is known as TX leakage and can seriously affect the performance of the receiver. A transmitter leakage canceller structure is proposed in this paper in order to improve isolation between the transmitter and receiver. The simulations...