The present invention is designed to improve spectral efficiency in a radio communication system which can use non-orthogonal multiple access (NOMA). Steps are provided in which a radio base station configures one of a plurality of transmission mode including a first transmission mode, which groups a plurality of transmission methods including a transmission method to employ non-orthogonal multiple access (NOMA) and multiple-user multiple-input and multiple-output (MU-MIMO), and a second transmission mode, which groups a plurality of transmission methods including a transmission method to employ this NOMA and open-loop transmit diversity, and transmits a downlink signal for this user terminal based on the configured transmission mode.

Radio base station, user terminal, and radio communication method

A system and method are described which enable planned evolution and obsolescence of multiuser wireless spectrum. One embodiment of such a system includes one or multiple centralized processors and one or multiple distributed nodes that communicate via wireline or wireless connections. The distributed nodes may share their identification number and other reconfigurable system parameters with the centralized processor. The information about all distributed nodes may be stored in a database that is shared by all centralized processors. The reconfigurable system parameters may comprise power emission, frequency band, modulation/coding scheme. The distributed nodes may be software defined radios such as FPGA, DSP, GPU and/or GPCPU that run algorithms for baseband signal processing and may be reconfigured remotely by the centralized processor. A cloud wireless system may be used wherein the distributed nodes are reconfigured periodically or instantly to adjust to the evolving wireless architecture.

System and methods for planned evolution and obsolescence of multiuser spectrum

A system and methods are described which compensate for the adverse effect of Doppler on the performance of DIDO systems. One embodiment of such a system employs different selection algorithms to adaptively adjust the active BTSs to different UEs based by tracking the changing channel conditions. Another embodiment utilizes channel prediction to estimate the future CSI or DIDO precoding weights, thereby eliminating errors due to outdated CSI.

System and methods to compensate for Doppler effects in multi-user (MU) multiple antenna systems (MAS)

Full length article: LTE-Advanced and the evolution to Beyond 4G (B4G) systems

Systems and methods are described for coordinating transmissions in distributed wireless systems via user clustering. For example, a method according to one embodiment of the invention comprises: measuring link quality between a target user and a plurality of distributed-input distributed- output (DIDO) distributed antennas of base transceiver stations (BTSs); using the link quality measurements to define a user cluster; measuring channel state information (CSI) between each user and each DIDO antenna within a defined user cluster; and precoding data transmissions between each DIDO antenna and each user within the user cluster based on the measured CSI.

Systems and methods to coordinate transmissions in distributed wireless systems via user clustering

A relatively recent idea of extending the benefits of MIMO systems to multiuser scenarios seems promising in the context of achieving high data rates envisioned for future cellular standards after 3G (3rd Generation). Although substantial research has been done on the theoretical front, recent focus is on making Multiuser Multiple-Input Multiple-Output (MUMIMO) practically realizable. This paper presents an overview of the different MU-MIMO schemes included/being studied in 3GPP standardization from LTE (long-term evolution) to LTE Advanced. MU-MIMO system concepts and implementation aspects have been studied here. Various low-complexity receiver architectures are investigated, and their performance assessed through link-level simulations. Appealing performance offered by low-complexity interference aware (IA) receivers is notably emphasized. Furthermore, system level simulations for LTE Release 8 are provided. Interestingly, it is shown that MU-MIMO only offers marginal performance gains with respect to single-user MIMO. This arises from the limited MU-MIMO features included in Release 8 and calls for improved schemes for the upcoming releases.

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MU-MIMO in LTE Systems

In the context of a wireless communication infrastructure, the Licensed Shared Access (LSA) concept is currently being developed by CEPT regulation and ETSI standardization bodies, with the aim of enabling cellular operators to have access to further spectral resources on a licensed shared basis. Even though spectrum owners, also known as Incumbents, will cooperate with cellular operators in the framework of a Sharing Agreement that is typically set-up for a long-term basis, the LSA concept will in addition, under specific conditions, give Incumbents the opportunity to reclaim spectrum on a per-need basis. Obviously, this new concept for managing spectrum introduces a number of novel challenges, such as vacate in a coordinated manner the LSA bands in case of a corresponding request being triggered by Incumbents, coordinate the LSA spectrum when it is used in proximity to neighbouring countries and/or regulation domains, establish protection zones in which maximum interference levels are guaranteed to Incumbents, etc. This paper gives an overview on the LSA state-of-the-art and elaborates the key challenges to be addressed in the future design of LSA systems.

Licensed shared access — State-of-the-art and current challenges

The market success of broadband multimedia-enabled devices such as smart phones, tablets, and laptops is increasing the demand for wireless data capacity in mobile cellular systems. In order to meet such requirements, the introduction of advanced techniques for increasing the efficiency in spectrum usage was required. Multi User -Multiple Input Multiple Output (MU-MIMO) and Carrier Aggregation (CA) are two important techniques addressed by 3GPP for LTE and LTE-Advanced. The aim of the EU FP7 project on “Spectrum Aggregation and Multi-user-MIMO: real-World Impact” (SAMURAI) is to investigate innovative techniques in the area of MU-MIMO and CA with particular focus on the practical, real-life, implementation and system deployment aspects. In the present paper, we provided an overview of the up-to-date SAMURAI contributions together with a description of the SAMURAI demonstrators developed as core part of the project.

/pdf/multi-user-mimo-and-carrier-aggregation-in-4g-systems-the-4ht4bwhl5o.pdf

Multi-user MIMO and Carrier Aggregation in 4G systems: The SAMURAI approach

A multi user receiver configured to receive a signal including multiple symbol streams assigned to various users is described. The multiple symbol streams include at least one first symbol stream assigned to a user of the multi user receiver and at least one second symbol stream assigned to another user, wherein a modulation alphabet applied for the at least one second symbol stream is unknown at the multi user receiver. The multi user receiver includes a symbol stream election unit configured to elect a symbol stream of the multiple symbol streams, an equalizer configured to provide an equalized symbol of the elected symbol stream, and a detector configured to generate a detected symbol from the equalized symbol on the basis of a constellation, wherein, if the second symbol stream is elected, the constellation is a mixed constellation including constellation points of at least two of multiple predefined modulation alphabets.

Receiver with multi layer interference cancellation

A receiver is configured to receive a receive signal including a plurality of signal components, each signal component indicating a channel of an antenna port and an associated scrambling sequence, wherein a first one of the channels indicated by a first one of the signal components which is based on a first scrambling sequence is allocated to the receiver for data reception and a second one of the channels indicated by a second one of the signal components which is based on a second scrambling sequence different from the first scrambling sequence is interfering with the allocated channel. The receiver includes an interference reduction unit configured to combine an estimate of the first one of the signal components and an estimate of the second one of the signal components to provide an interference-reduced signal.

Biljana Badic

Papers

MU-MIMO in LTE Systems

Licensed shared access — State-of-the-art and current challenges

Multi-user MIMO and Carrier Aggregation in 4G systems: The SAMURAI approach

Receiver with multi layer interference cancellation

Receiver, receiver circuits and methods for providing an interference-reduced signal