The emerging massive/large-scale multiple-input multiple-output (LS-MIMO) systems that rely on very large antenna arrays have become a hot topic of wireless communications. Compared to multi-antenna aided systems being built at the time of this writing, such as the long-term evolution (LTE) based fourth generation (4G) mobile communication system which allows for up to eight antenna elements at the base station (BS), the LS-MIMO system entails an unprecedented number of antennas, say 100 or more, at the BS. The huge leap in the number of BS antennas opens the door to a new research field in communication theory, propagation and electronics, where random matrix theory begins to play a dominant role. Interestingly, LS-MIMOs also constitute a perfect example of one of the key philosophical principles of the Hegelian Dialectics, namely, that “quantitative change leads to qualitative change.” In this treatise, we provide a recital on the historic heritages and novel challenges facing LS-MIMOs from a detection perspective. First, we highlight the fundamentals of MIMO detection, including the nature of co-channel interference (CCI), the generality of the MIMO detection problem, the received signal models of both linear memoryless MIMO channels and dispersive MIMO channels exhibiting memory, as well as the complex-valued versus real-valued MIMO system models. Then, an extensive review of the representative MIMO detection methods conceived during the past 50 years (1965–2015) is presented, and relevant insights as well as lessons are inferred for the sake of designing complexity-scalable MIMO detection algorithms that are potentially applicable to LS-MIMO systems. Furthermore, we divide the LS-MIMO systems into two types, and elaborate on the distinct detection strategies suitable for each of them. The type-I LS-MIMO corresponds to the case where the number of active users is much smaller than the number of BS antennas, which is currently the mainstream definition of LS-MIMO. The type-II LS-MIMO corresponds to the case where the number of active users is comparable to the number of BS antennas. Finally, we discuss the applicability of existing MIMO detection algorithms in LS-MIMO systems, and review some of the recent advances in LS-MIMO detection.

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Fifty Years of MIMO Detection: The Road to Large-Scale MIMOs

The present invention is designed to provide a user terminal, a radio base station and a radio communication method of novel structures that can achieve a good communication environment. A radio base station non-orthogonal-multiplexes downlink signals for a plurality of user terminals over a given radio resource, a user terminal having received the downlink signals for the plurality of user terminals decodes downlink signal for another user terminal, judges whether or not the downlink signal for the other user terminal has been successfully received, based on the decoding result of the downlink signal, reports a judgement result as to whether or not the downlink signal for the other user terminal has been successfully received and a judgement result as to whether or not a downlink signal for the user terminal has been successfully received, to the radio base station, and then the radio base station executes retransmission control of downlink signals based on reports from the user terminal.

User terminal, radio base station and radio communication method

A wireless telecommunication system comprises base stations for communicating with terminal devices. One or more base stations support a power boost operating mode in which a base station's available transmission power is concentrated in a subset of its available transmission resources to provide enhanced transmission powers as compared to transmission powers on these transmission resources when the base station is not operating in the power boost mode. A base station establishes an extent to which one or more base stations in the wireless telecommunications system support the power boost operating mode conveys an indication of this to a terminal device. The terminal device receives the indication and uses the corresponding information to control its acquisition of a base station of the wireless telecommunication system, for example by taking account of which base stations support power boosting and/or when power boosting is supported during a cell attach procedure.

Telecommunications apparatus and methods

This chapter contains sections titled: Introduction Overview of Multicarrier CDMA Systems Channel Model Performance of MC-CDMA System Performance of Overlapping Multicarrier DS-CDMA Systems Performance of Multicarrier DS-CDMA-I Systems Performance of AMC DS-CDMA Systems Performance of SFH/MC DS-CDMA Systems Chapter Summary and Conclusion 
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Overview of Multicarrier CDMA

There is described an indicia reading terminal that can be operative to capture a succession of frames of image data and that can be operative so that a certain frame of the succession of frames is subject to quality evaluation processing where a result of the quality evaluation processing is responsive to one or more of an incidence and sharpness of edge representations of the frame of image data.

Indicia reading terminal including frame quality evaluation processing

A very high-speed wireless access of 100 Mb/s to 1 Gb/s is required for fourth-generation mobile communications systems. However, for such high-speed data transmissions, the channel is severely frequency-selective due to the presence of many interfering paths with different time delays. A promising wireless access technique that can overcome the channel frequency-selectivity and even take advantage of this selectivity to improve the transmission performance is CDMA. There may be two approaches in CDMA technique: direct sequence CDMA and multicarrier CDMA. A lot of attention is paid to MC-CDMA. However, recently it has been revealed that DS-CDMA can achieve good performance comparable to MC-CDMA if proper frequency domain equalization is adopted. This article discusses their similarities and performances. A major transmission mode in 4G systems is packet-based. Automatic repeat request combined with channel coding is a very important technique. Recent research activity on this technique is also introduced.

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Broadband CDMA techniques

Recently, frequency-domain equalization (FDE) has been attracting much attention as a way to improve single-carrier (SC) signal transmission in a frequency-selective wireless channel. Since the SC signal spectrum is spread over the entire signal bandwidth, FDE can take advantage of channel frequency-selectivity and achieve the frequency diversity gain. SC with FDE is a promising wireless signal transmission technique. In this article, we review the pioneering research done on SC with FDE. The principles of simple one-tap FDE, channel estimation, and residual inter-symbol interference (ISI) cancellation are presented. Multi-input/multi-output (MIMO) is an important technique to improve the transmission performance. Some of the studies on MIMO/SC with FDE are introduced.

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Introduction of Frequency-Domain Signal Processing to Broadband Single-Carrier Transmissions in a Wireless Channel

SUMMARY Single-carrier (SC) multiple access is a promising uplink multiple access technique because of its low peak-to-average power ratio (PAPR) property and high frequency diversity gain that is achievable through simple one-tap frequency-domain equalization (FDE) in a strong frequency-selective channel. The multiple access capability can be obtained by combining either frequency division multiple access (FDMA) or code division multiple access (CDMA) with SC transmission. In this article, we review the recent research on the SC multiple access techniques with one-tap FDE. After introducing the principle of joint FDE/antenna diversity combining, we review various SC multiple access techniques with one-tap FDE, i.e., SC-FDMA, SC-CDMA, block spread CDMA, and

https://www.mobile.ecei.tohoku.ac.jp/paper/pdf/publish_2009/04_pu_2009_adachi.pdf

Frequency-Domain Equalization for Broadband Single-Carrier Multiple Access

The present invention aims at allowing a demodulation reference signal (DMRS) pattern suitable for a terminal to be selected from among a plurality of DMRS patterns including Legacy DMRS and Reduced DMRS. Disclosed is a terminal including: reception section (21) that receives uplink control information; control section (23) that determines a specific mapping pattern from among a plurality of mapping patterns for an uplink DMRS on the basis of the control information; and DMRS generating section (24) that generates a DMRS according to the specific mapping pattern.

Terminal, base station, method of generating dmrs, and transmission method

Disclosed is a transmission apparatus which enables high transmission-rate communication by mapping DMRSs in a way adapted to the reception environment of each terminal. The transmission apparatus includes: reference signal configuration section (101) that configures a DMRS mapping pattern for each terminal and outputs a DMRS and information indicating the DMRS mapping pattern; and transmission section (106) that transmits a transmission signal including the information indicating the DMRS mapping pattern configured by reference signal configuration section (101) and the DMRS mapped according to the DMRS mapping pattern to the terminal.

Kazuki Takeda

Papers

Broadband CDMA techniques

Introduction of Frequency-Domain Signal Processing to Broadband Single-Carrier Transmissions in a Wireless Channel

Frequency-Domain Equalization for Broadband Single-Carrier Multiple Access

Terminal, base station, method of generating dmrs, and transmission method

Transmission apparatus and control signal mapping method