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Finding optimal routes and spectrum allocation in flexgrid optical networks, known as the RSA problem, is an important design problem in transport communication networks. The problem is NP -hard, and its intractability becomes profound when network instances with several tens of nodes and several hundreds of demands are to be solved to optimum. In order to deal with such instances, large-scale opt
This paper presents a multimode soft-output multiple-input multiple-output (MIMO) signal detector that is efficient in hardware cost and energy consumption. The detector is capable of dealing with spatial-multiplexing (SM),break space-division-multiple-access (SDMA), and spatial-diversity (SD) signals of 4 ✕ 4 antenna and 64-QAM modulation. Implementation-friendly algorithms, which reuse most of t
In this work a low power 5th order chebyshev active-RC low pass filter that meets Rel-8 LTE receiver requirements has been designed with programmable bandwidth and overshoot. Designed for a homodyne LTE receiver, filter bandwidths from 700kHz to 10MHz are supported. The bandwidth of the operational amplifiers is improved using a novel phase enhancement technique. The filter was implemented in 65nm
Abstract in Undeterminedhis survey deals with computational complexity of column generation problems arising in the design of survivable communication networks. Such problems are often modeled as linear programs based on noncompact multicommodity flow network formulations. These formulations involve an exponential number of path-flow variables, and therefore require column generation to be solved
In this work we present a fully integrated Radio-Fiber interface implemented in 65nm CMOS, intended for remote antenna units (RAUs) in distributed antenna systems. To relax the requirements on the optical components, an intermediate frequency (IF) signal (100MHz) is transmitted over the multi-mode fiber, which is then up-converted to 2.2GHz inside the RAU. Local Oscillator (LO) signals to the mixe
In this paper a number of low-complexity channel estimator structures tailored to the needs of LTE terminals have been investigated. The focus has been on the algorithms exhibiting reduced complexity while providing an acceptable level of performance. To design these estimators other factors such as interoperability with another OFDM-based standard, DVB-H, in a multi-standard environment have been
A general coupling-based model framework for wideband multiple-input multiple-output (MIMO) channels is presented in this paper. Under this framework, the channel state information (CSI) tensor can be expressed by the product of a coupling tensor, a complex Gaussian tensor and three unitary matrices. The unitary matrices can be either eigenbases or steering matrices in different domains. The coupl
In this paper, we present a novel approach for the design of rate-maximizing channel shortening detectors with soft feedback side information for frequency-selective channels. The detector is a soft-input soft-output detector and constitutes one of the components of an iterative receiver. The design optimization is performed from an information-theoretic perspective where we maximize the achievabl
This paper presents a front-end architecture for fully integrated 60 GHz phased array receivers. It employs LO-path beamforming using a phase controlled phase-locked loop (PC-PLL). To demonstrate the architecture a circuit is implemented featuring a two stage low noise amplifier, two cascaded active mixers, and a PC-PLL. The receiver downconverts the 60 GHz signal in two steps, using LO signals fr
In this work a 2.2 GHz quadrature receiver front-end suitable for low-power applications is presented. The low-noise amplifier, the mixer and the voltage-controlled oscillator are merged into a single stage, making the circuit capable of extreme current reuse while keeping it still functional at low supply voltage. A careful linear time-variant analysis is proven to be necessary to accurately pred
As new systems and applications are introduced for next-generation wireless systems, the propagation channels in which they operate need to be characterized. This paper discusses propagation channels for four types of next-generation systems: (i) distributed Multiple-Input Multiple-Output (MIMO) and Cooperative MultiPoint (CoMP), systems, which require the characterization of correlation between c
Service discovery is central in pervasive middleware systems, built on top of the communication substrate using the more fundamental mechanisms for device discovery. In mobile pervasive systems devices come and go, and switch network frequently, demanding support for device discovery across heterogeneous networks. We present the design of a device discovery mechanism for the PalCom middleware that
The Bidirectional Efficient Algorithm for Searching code Trees (BEAST), which is an algorithm to efficiently determine the free distance and spectral components of convolutional encoders, is implemented for the Cell Broadband Engine Architecture, efficiently utilizing the underlying hardware. Exhaustive and random searches are carried out, presenting new rate R=1/2 convolutional encoding matrices
Massive MIMO can greatly increase both spectral and transmit-energy efficiency. This is achieved by allowing the number of antennas and RF chains to grow very large. However, the challenges include high system complexity and hardware energy consumption. Here we investigate the possibilities to reduce the required number of RF chains, by performing antenna selection. While this approach is not a ve
A low power wideband low noise amplifier (LNA) was designed and implemented in SiGe HBT technology. The measured noise figure is less than or equal to 1 dB in almost the entire L-band. The gain in the L-band is above 13 dB with a gain variation of 4 dB. Hence, it’s useful for present as well as future GNSS applications. The current consumption is 5 mA from a single supply of +5V. The stability of
