Wireless Communications

A cellular base station serves a multiplicity of single-antenna terminals over the same time-frequency interval. Time-division duplex operation combined with reverse-link pilots enables the base station to estimate the reciprocal forward- and reverse-link channels. The conjugate-transpose of the channel estimates are used as a linear precoder and combiner respectively on the forward and reverse links. Propagation, unknown to both terminals and base station, comprises fast fading, log-normal shadow fading, and geometric attenuation. In the limit of an infinite number of antennas a complete multi-cellular analysis, which accounts for inter-cellular interference and the overhead and errors associated with channel-state information, yields a number of mathematically exact conclusions and points to a desirable direction towards which cellular wireless could evolve. In particular the effects of uncorrelated noise and fast fading vanish, throughput and the number of terminals are independent of the size of the cells, spectral efficiency is independent of bandwidth, and the required transmitted energy per bit vanishes. The only remaining impairment is inter-cellular interference caused by re-use of the pilot sequences in other cells (pilot contamination) which does not vanish with unlimited number of antennas.

Noncooperative Cellular Wireless with Unlimited Numbers of Base Station Antennas

Multiple-input multiple-output (MIMO) technology is maturing and is being incorporated into emerging wireless broadband standards like long-term evolution (LTE) [1]. For example, the LTE standard allows for up to eight antenna ports at the base station. Basically, the more antennas the transmitter/receiver is equipped with, and the more degrees of freedom that the propagation channel can provide, the better the performance in terms of data rate or link reliability. More precisely, on a quasi static channel where a code word spans across only one time and frequency coherence interval, the reliability of a point-to-point MIMO link scales according to Prob(link outage) ` SNR-ntnr where nt and nr are the numbers of transmit and receive antennas, respectively, and signal-to-noise ratio is denoted by SNR. On a channel that varies rapidly as a function of time and frequency, and where circumstances permit coding across many channel coherence intervals, the achievable rate scales as min(nt, nr) log(1 + SNR). The gains in multiuser systems are even more impressive, because such systems offer the possibility to transmit simultaneously to several users and the flexibility to select what users to schedule for reception at any given point in time [2].

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Scaling Up MIMO: Opportunities and Challenges with Very Large Arrays

The quintessential goal of sensor array signal processing is the estimation of parameters by fusing temporal and spatial information, captured via sampling a wavefield with a set of judiciously placed antenna sensors. The wavefield is assumed to be generated by a finite number of emitters, and contains information about signal parameters characterizing the emitters. A review of the area of array processing is given. The focus is on parameter estimation methods, and many relevant problems are only briefly mentioned. We emphasize the relatively more recent subspace-based methods in relation to beamforming. The article consists of background material and of the basic problem formulation. Then we introduce spectral-based algorithmic solutions to the signal parameter estimation problem. We contrast these suboptimal solutions to parametric methods. Techniques derived from maximum likelihood principles as well as geometric arguments are covered. Later, a number of more specialized research topics are briefly reviewed. Then, we look at a number of real-world problems for which sensor array processing methods have been applied. We also include an example with real experimental data involving closely spaced emitters and highly correlated signals, as well as a manufacturing application example.

Two decades of array signal processing research: the parametric approach

It is shown that, particularly for terrestrial cellular telephony, the interference-suppression feature of CDMA (code division multiple access) can result in a many-fold increase in capacity over analog and even over competing digital techniques. A single-cell system, such as a hubbed satellite network, is addressed, and the basic expression for capacity is developed. The corresponding expressions for a multiple-cell system are derived. and the distribution on the number of users supportable per cell is determined. It is concluded that properly augmented and power-controlled multiple-cell CDMA promises a quantum increase in current cellular capacity. >

On the capacity of a cellular CDMA system

Radio resources are allocated to communication between a mobile station (40) and a base station (20) The available set of radio resources may comprise radio resources primarily assigned to a neighbouring cell if the 5 mobile station (40) experience an instantaneous low level of co-channel interference from such neighbouring cells The existence of interference is preferably deduced from signal quality measurements of pilot signals The allocation may concern uplink and/or downlink (54) communication Devices (41) for performing the measurements are located in the mobile station (40), while devices for performing the evaluation (22), selection (23) and actual allocation (24) can be placed in different parts of the communications system- in the mobile station (40), in a base station (20) or In a core network node (70), or as a distributed means

Dynamic allocation of radio resources

The upcoming 5G specifications from 3GPP, to be available in 2018, will include LTE-Advanced Pro as well as a new 5G radio-access technology. This practical and very successful book, written by engineers working closely with 3GPP, gives insight into the newest technologies and standards adopted by 3GPP, with detailed explanations of the specific solutions chosen and their implementation in LTE, LTE-Advanced, and LTE-Advanced Pro, as well as providing a detailed description of the path to 5G and the associated underlying technologies. This edition has been thoroughly revised and updated to reflect the large extensions to LTE as introduced in 3GPP Releases 12 and 13 and the role of LTE in the upcoming 5G era. New to this edition includes updated content on: 4G and 5G Radio Access Spectrum for 4G and 5G Machine-Type Communication Device-to-Device Communication License-assisted Access Full-dimension MIMOSmall-cell enhancements, eIMTA, FDD+TDD aggregation, dual connectivity Requirements on and general structure of 5G wireless access, addressing the existing and new usage scenarios for 5GTechnical solutions for the new 5G radio-access technology The authors of this book all work at Ericsson Research and have been deeply involved in 3G and 4G development and standardization. They are leading experts in the field and are today actively contributing to the standardization of 4G and 5G within 3GPP.The leading book on 3GPP specifications for LTE, LTE-Advanced, and LTE-Advanced Pro covering up to and including Release 13, written by Ericsson engineers who are heavily involved in the development of 3GPP specificationsTen new chapters and coverage of all major features introduced with Release 12 and 13Two completely new chapters on 5G wireless access including a detailed description of the key technology components under development by 3GPP

4G, LTE-Advanced Pro and The Road to 5G Ed. 3

A network unit of an own cell is operated in a radio communication system utilizing a radio interface that includes a radio frame made up of a number of sub-frames. The own cell serves one or more user equipments. Operation includes obtaining information about a scheduling of MBSFN data transmissions in one or more neighboring cells. The information thereby obtained is used to generate an information signal that, for a given sub-frame, enables the one or more user equipments to determine whether neighboring cell measurements can be performed using a unicast group of Orthogonal Frequency Division Multiple access (OFDM) symbols. The information signal is transmitted to the one or more user equipments, which can then use the information to determine how to locate cell-specific reference symbols when doing measurements of neighboring cells.

Measurement of cell-specific reference symbols in the presence of mbms single frequency network transmissions

Embodiments herein relate to a method in a user equipment (10) for transmitting uplink control information in time slots in a subframe over a radio channel to a radio base station. The radio channel is arranged to carry uplink control information and the user equipment and radio base station are comprised in a radio communications network. The uplink control information is comprised in a block of bits. The user equipment maps the block of bits to a sequence of complex valued modulation symbols. The user equipment also block spreads the sequence of complex valued modulation symbols across Discrete Fourier Transform Spread - Orthogonal Frequency Division Multiplexing (DFTS-OFDM) symbols. This is performed by applying a spreading sequence to the sequence of complex valued modulation symbols, to achieve a block spread sequence of complex valued modulation symbols. The user equipment further transforms the block-spread sequence of complex valued modulation symbols per DFTS-OFDM symbol. This is performed by applying a matrix that depends on a DFTS- OFDM symbol index and/or slot index to the block-spread sequence of complex valued modulation symbols. The user equipment also transmits the block spread sequence of complex valued modulation symbols that has been transformed over the radio channel to the radio base station.

Radio base station and user equipment and methods therein

A radio base station transmits data symbols to a mobile terminal on multiple frequency carriers, e.g., in accordance with the MC-WCDMA or cmda2000 3x air interface protocols. The radio base station instructs the mobile terminal to report channel quality measurements obtained by the terminal for the multiple carriers over the same uplink channel during successive reporting intervals. According to one embodiment, the mobile terminal reports channel quality by receiving data symbols transmitted on a plurality of frequency carriers in a multi-carrier CDMA environment and measuring channel quality for the different frequency carriers. The mobile terminal reports individual ones of the channel quality measurements over the same uplink channel during successive reporting intervals.

Stefan Parkvall

Papers

Dynamic allocation of radio resources

4G, LTE-Advanced Pro and The Road to 5G Ed. 3

Measurement of cell-specific reference symbols in the presence of mbms single frequency network transmissions

Radio base station and user equipment and methods therein

Multi-carrier CQI feedback method and apparatus