We consider in-band self-backhauling for small cell 5G systems. In-band enables efficient usage of frequency resources. When coupled with a flexible frame format, it also time-division duplexing uplink, downlink, and backhaul transmissions. Self-backhauling is particularly when FD relaying. Antenna design, as well cancellation in radio digital domains at an relay reuse the same resources access hops. The use hops can be coordinated to maximize end-to-end performance. evaluate indoor...

We consider product codebook strategy where a single small is implemented at the receiver to quantize larger multi-input multi-output (MIMO) channels, e.g. aggregate channels of cooperative MIMO base stations. The present work focuses on design, construction, and codeword selection under this scenario, for single- or multistream transmission. Designing point-to-point unitary precoding related discretization problem Grassmann manifold, Grassmannian an equivalence class...

5G physical random access channel (PRACH) will use new preamble formats based on short Zadoff-Chu (ZC) sequences to enable cases. These result however in a PRACH capacity shortfall where the number of available for network planning may just be enough support few cells without sequence reuse. To overcome this issue, two enlarged constant-amplitude constructions that include ZC sequences, and thus being backward-compatible with current design, are presented. Both feature desirable subset...

Precoding codebook design for limited feedback MIMO systems is known to reduce a discretization problem on Grassmann manifold. The case of two-antenna beamforming special in that it equivalent quantizing the real sphere. isometry between Grassmannian G <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2,1</sub> <sup xmlns:xlink="http://www.w3.org/1999/xlink">ℂ</sup> and sphere <i xmlns:xlink="http://www.w3.org/1999/xlink">S</i>...

This paper proposes new approach to relay selection using a threshold-based transmission protocol for system with multiple amplify-and-forward relays and users. The novelty of this includes (1) economical feedback that reduces signal processing complexity, as well (2) adaptively interrupted can save significant RF power when the requirement is not met. Applied downlink, uses threshold on first-hop (base-station-to-relay) SNR selection. One-bit sent from each base station, reporting...

This paper provides a proof of global convergence gradient search for low-rank matrix approximation. Such approximations have recently been interest large-scale problems, as well dictionary learning sparse signal representations and completion. The is based on the interpretation problem an optimization Grassmann manifold Fubiny-Study distance this space.

A construction of Grassmannian packings related to representation theory is applied build implementation-friendly MIMO precoding codebooks when the number transmit antennas a power prime. Using chordal distance as metric, some corresponding appear be optimal by meeting othoplex bound. Also, using only codewords, smaller satisfying equal per antenna constraint may found. Optimality with reference this shown modification Conway-Hardin-Sloane's spherical embedding Grassmann manifold for...

5G physical random access channel (PRACH) will use several new preamble formats in order to enable cases. These formats, however, results a PRACH capacity shortfall. In this paper, we propose solution based on an extension of the LTE sequence set. Cell-specific sequences are derived from single-root Zadoff-Chu (ZC) with zero-correlation zone, and if necessary, different m-sequence covers instead multiple roots as LTE. While construction is shown preserve similar low-correlation zone design,...

A new approach to relay and user selection is proposed using threshold-based transmission reduce outage probability save transmit power. By exploiting properties of dual-hop amplify-and-forward (AF) relaying, (TRU) protocols that employ one-bit channel state information (CSI) feedback are for multiple-relay, multiple-user systems. These have the advantages (1) economical feedback, (2) optional adaptive power-saving transmission. Centralized (CS) distributed (DS) policies as well...

Volume estimates of metric balls in manifolds find diverse applications information and coding theory. In this paper, new results for the volume a ball unitary group are derived via tools from random matrix The first result is an integral representation exact volume, which involves Toeplitz determinant Bessel functions. A simple but accurate limiting formula then obtained by invoking Szegö's strong limit theorem large matrices. asymptotic enables analytical evaluation some coding-theoretic...

Grassmannian frames in composite dimensions D are constructed as a collection of orthogonal bases where each is the element-wise product mask sequence with generalized Hadamard matrix. The set sequences obtained by exponentiation q-root unity different quadratic forms m variables, q and unique primes total number primes, respectively, prime decomposition D. This method generalization well-known construction mutually unbiased bases, well second-order Reed-Muller for power-of-two dimension = 2...

We discuss group orbits to construct codes in the complex Grassmann manifold. Finite subgroups of unitary act naturally on Given an irreducible representation appropriate degree, its center has no effect orbit construction. Thus, generate codes, projective representations finite groups are specific interest. Following this principle, we derive basic properties and describe explicit constructions leading some optimum packings 2 4 dimensions.

We compute the volume of Stiefel manifold induced by canonical embedding as a surface in Euclidean hypersphere and taking corresponding Euclidean/chordal distance. Exploiting power series expansion element, small metric ball under chordal distance is evaluated. Evaluating critical to derive Hamming-type bounds. Using spherical argument, we provide results generalizing previously known bounds on codes Grassmann unitary group.

A multi-input multi-output orthogonal frequency division multiplexing system using spectral precoding to reduce out-of-band power emission is considered. For single-antenna systems, existing precoders that maintain the transmission rate cannot be linearly inverted, calling for iterative interference cancellation receivers. In this letter, it shown such when combined with a multiple-antenna can allow well-defined zero-forcing equalization. Numerical results show proposed receivers achieve...

The density of a code is the fraction coding space covered by packing balls centered around codewords. A high indicates that performs well when used as uniform point-wise discretization an ambient space. This paper investigates codes in complex Stiefel and Grassmann manifolds equipped with chordal distance arising from Euclidean embedding, including unitary group special case. choice enables treatment subspaces hyperspheres. In this geometry, densest packings are not necessarily equivalent...

Among the requirements of 5th generation (5G) radio access technology (RAT) is that associated waveform be well-localised in time and frequency. Localisation characteristics waveforms are important when considering multiplexing duplexing transmissions. This paper proposes a measure time-frequency localisation (TFL) for sets orthogonal waveforms, based on Heisenberg's well-known Uncertainty Principle, allowing containment OFDM FBMC multicarrier signals over entire bandwidth to determined. A...

We discuss group orbits codes in homogeneous spaces for the unitary group, known as flag manifolds. The distances used to describe arise from embedding manifolds into Euclidean hyperspheres, providing a generalization of spherical Grassmann equipped with so-called chordal distance. Flag are constructed by acting representation finite group. In construction, center has no effect, and thus it is sufficient consider its inner automorphism Accordingly, some explicit constructions projective...

We investigate the density of codes in complex Grassmann manifolds G <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ℂ</sup> <sub xmlns:xlink="http://www.w3.org/1999/xlink">n,p</sub> equipped with chordal distance. The a code is defined as fraction Grassmannian covered by `kissing' balls equal radius centered around codewords. kissing cannot be determined solely from minimum distance, nonetheless upper and lower bounds function distance only are...

This paper investigates the application of N-continuous spectral projection precoding design to single-carrier frequency-division multiple access (SC-FDMA). It first considers a general orthogonal projection-based precoded system with an improved iterative receiver and analyzes its ultimate performance in additive white Gaussian noise channel, both terms achievable throughput symbol-error rates. For SC-FDMA, distribution symbol errors is very much asymmetric; few base pulses carry lion share...

Volume of metric balls relates to rate-distortion theory and packing bounds on codes. In this paper, the volume in complex Grassmann manifolds is evaluated for an arbitrary radius. The ball defined as a set hyperplanes fixed dimension with reference center possibly different dimensions, generalized chordal distance unequal dimensional subspaces used. First, reduced 1-D integral representation. overall problem boils down evaluating determinant matrix same size subspace dimensionality....

Volume estimates of metric balls in manifolds find diverse applications information and coding theory. In this paper, some new results for the volume a ball unitary group are derived via various tools from random matrix The first result is an integral representation exact volume, which involves Toeplitz determinant Bessel functions. connection to matrix-variate hypergeometric functions Szeg\H{o}'s strong limit theorem lead independently finite size formula asymptotic one. convergence...

Base station cooperation is expected to enhance spectrum efficiency of future cellular system. Performance heavily depends on the channel state information available at transmitter. In practical systems, are acquire through a limited feedback channel. Typically, quantization receiver side done with fixed pre-designed codebook. this paper, we consider codebook design and codeword selection problem when product employed, reusing point-to-point Point-to-point codebooks often designed as...

We propose a novel method to construct beam codebooks, i.e. set of beamforming weights, for sweeping and data transmission in mmWave massive MIMO channels. The proposed codebooks are designed according the statistical distribution channel's angles departure order efficiently sweep angular space covered by beams. first present general closed-form construction an arbitrary then tailor results Laplace distribution. resulting beams priori better adapted channel statistics thus enhance spectral...