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

The present invention relates to a method and arrangement for efficient use of network resources, in particular for continuous connectivity services. The present invention introduces a set of established rules for uplink and/or downlink activity detection such that a Node B and/or a UE is enabled to detect active and inactive transmission periods on links for reception of packet data transmission and can independently arrange for inactivity/activity state transitions without any need of further signalling. Such a set of rules can be communicated to the Node B and the user equipment, e.g., from the radio network controller (RNC), or can consist of a predefined set of fixed rules that is readily implemented in said units.

Method and Arrangement for Activity Detection in a Telecommunication System

The present invention is directed to methods in a wireless communication network for allocating resource elements of a transmission resource to a control channel. The invention also relates to different nodes of a wireless communication network. The transmission resource comprises a first number of resource blocks each comprising one or a plurality of subsets of resource elements. One method in a control node comprises the steps: obtaining a bitmap for configuration of the transmission resource, wherein the bitmap is adapted to identify at least one subset of resource elements within the transmission resource (S1); allocating the at least one identified subset of resource elements to the control channel (S2); and transmitting control data on the at least one subset of resource elements allocated to the control channel to a receiving node (S3).

Control channel configuration in a wireless communications system

Systems and methods are disclosed for transmission and reception of an uplink grant during a gap created in radio resources assigned by a previous multiple Transmit Time Interval (multi-TTI) uplink grant in a system operating according to a Time Division Duplexing (TDD) scheme. In one embodiment, a method of operation of a radio network node in a cellular communications network is provided. The method includes transmitting a first uplink grant that assigns radio resources for a multi-TTI uplink transmission, and transmitting a second uplink grant during a gap in the radio resources assigned by the first uplink grant. In one embodiment, by utilizing the gap to transmit the second uplink grant, uplink radio resources assigned for uplink transmission can be maximized, which is particularly beneficial in high uplink traffic conditions.

Uplink multi-tti scheduling in tdd system

A method for managing radio access comprises sending of a radio access technology (RAT) resource aggregation request from a first radio access network (RAN) to a second RAN concerning communication with a user equipment connected to a source RAN, and returning a response to the first RAN. The source RAN is the first or second RAN. The first and second RANs use different radio access technologies. Radio resources of a base station in a target RAN, the RAN to which the user equipment is not connected, are reserved. A report of the reserved radio resources is sent to the source RAN. A RAT resource aggregation command is transmitted to the user equipment. The RAT resource aggregation command comprises that a RAT resource aggregation shall be used and the reserved radio resources. The base stations have at least partly overlapping coverage areas.

Methods and Devices for Managing Radio Access in a Communication System

A radio frequency communication device (100, 320) comprising a radio frequency communications interface (130) and a controller (110), wherein said controller (110)is configured to: establish network communication with a network node (200, 310) and to establish device-to-device communication with a second radio frequency communication device (325) via said radio frequency communication interface (130). The controller is further configured to determine whether there is to be performed a simultaneous communication comprising a network transmission over said network communication with said network node (200, 310) and a D2D reception over said device-to-device communication with said second radio frequency communication device (325) or a network reception over said network communication with said network node (200, 310) and a D2D transmission over said device-to-device communication with said second radio frequency communication device (325); determine if there is a transmission problem related to said simultaneous communication; and if so determine a mitigation technique; and perform said network transmission and said D2D reception or said network reception and said D2D transmission according to said mitigation technique to mitigate said transmission problem.

Improved handling of simultaneous network communication transmission and d2d communication reception or simultaneous network communication reception and d2d communication transmission

Stefan Parkvall

Papers

Method and Arrangement for Activity Detection in a Telecommunication System

Control channel configuration in a wireless communications system

Uplink multi-tti scheduling in tdd system

Methods and Devices for Managing Radio Access in a Communication System

Improved handling of simultaneous network communication transmission and d2d communication reception or simultaneous network communication reception and d2d communication transmission