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

FIELD: wireless communication.SUBSTANCE: invention relates to the field of control signaling in a wireless communication system. Effect is achieved by following: in a wireless communication system (100), the access node (110) configures for a user device (UE) (105) each symbol in the slot (68a) separately as one of a plurality of possible symbol types. The types include an uplink symbol, a downlink symbol, and other symbol. The access node (110) transmits to the UE (105) an SFI determining the number of downlink symbols in the slot (68a) and the number of uplink symbols in the slot (68a) and indicating whether the slot (68a) includes other symbols. The UE (105) receives from the access node (110) the SFI for the slot (68a) and determines the type of each of the symbols in the slot (68a) based on the number of uplink symbols and the number of downlink symbols.EFFECT: technical result consists in ensuring the transmission of the slot format indicator (SFI) in efficient way.30 cl, 23 dwg

General control signals for efficient system operation

일 양태에서, 전송 노드는, 미리 결정된 길이를 갖는 제1 전송 간격에 걸쳐서 제1 UE로의 다운링크 전송을 스케줄링하고, 제1 전송 간격에서 제1 UE로의 다운링크 전송을 시작한다. 전송 노드는, 제1 UE로의 다운링크 전송에서 전송 홀의 제1 종단을 생성하기 위해 제1 전송 간격의 종단 이전에 제1 UE로의 다운링크 전송을 중단하고, 전송 홀의 제2 종단에서 제1 UE로의 다운링크 전송을 재개한다. 전송 노드는, 전송 홀 내에서, 제2 UE로부터의 업링크 전송을 수신하거나 더 높은 우선 순위 전송을 전송할 수 있다.

더 긴 전송 간격에서의 전송 홀

A method and apparatus according to the present invention addresses and/or prevents lost protocol synchronization in HARQ systems caused by ACK/NACK errors. The embodiment detects lost synchronization errors for NDI-less retransmission protocols. Protocol synchronization errors are prevented by sending scheduling grants (SCH) on a packet by packet basis. The receiver sends a subsequent explicit scheduling grant to the transmitter based on an error evaluation of a received PDU. The transmitter will not send the next PDU unless it receives the subsequent explicit scheduling grant.

NDI-less protocol synchronization for HARQ

Apparatuses and methods are disclosed for block interleaving. In one embodiment, a method includes generating an interleaver sequence for a control resource set, CORESET, configuration for a physical downlink control channel, the interleaver sequence associated with an interleaving matrix; optionally, for each one of an allowed value of number of rows for the interleaving matrix, determining a number of null entries to be added to the interleaving matrix; and selecting a number of rows. R, for the interleaving matrix such that the number of null entries to be added to the interleaving matrix is: no more than a number of columns, C, of the interleaving matrix; and optionally, the smallest among the numbers of null entries determined for each of the allowed values of number of rows for the interleaving matrix. In another embodiment, a method includes decomposing the interleaver sequence.

Wireless communication block interleaving

In this paper we consider the problem of estimating the propagation delays of the transmitted signals in an asynchronous direct-sequence code division multiple access (DS-CDMA) system operating over a fading channel. Two estimators based on subspace techniques are compared and the Cram er-Rao Bound, a lower bound on the variance of any unbiased estimator, is derived. Special attention is paid to the near-far problem.

Stefan Parkvall

Papers

General control signals for efficient system operation

더 긴 전송 간격에서의 전송 홀

NDI-less protocol synchronization for HARQ

Wireless communication block interleaving

Propagation Delay Estimation of Fading DS-CDMA Signals