The present invention relates to the field of coordinated multipoint transmission and reception (CoMP) in wireless communication networks, in particular to methods, an apparatus, and a network node for use in performing coordinated data transmissions in a wireless communication network. A method for use in a network node for coordinating data transmission to user equipments in a wireless communication network, wherein the wireless communication network comprising at least two access nodes each access node having one or more antennas and being arranged to perform coordinated data transmissions to user equipments is provided. The method comprising: obtaining signal strength values associated with the one or more antennas of the at least two access nodes for a number of user equipments; arranging the number of user equipments into one or more groups of user equipments and associating each of the one or more groups of user equipments with a sub-set of the one or more antennas of the at least two access nodes based on the obtained signal strength values; and coordinating data transmission performed by the at least two access nodes to each of the one or more groups of user equipments based on the subset of the one or more antennas of the at least two access nodes associated with each group of user equipments, respectively.

Performing Coordinated Multipoint Transmission and Reception (CoMP) in a Wireless Communication Network

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

In order to satisfy the requirements of future IMT-Advanced mobile systems, the concept of spectrum aggregation is introduced by 3GPP in its new LTE-Advanced (LTE Rel. 10) standards. While spectrum aggregation allows aggregation of carrier components (CCs) dispersed within and across different bands (intra/inter-band) as well as combination of CCs having different bandwidths, spectrum aggregation is expected to provide a powerful boost to the user throughput in LTE-Advanced (LTE-A). However, introduction of spectrum aggregation or carrier aggregation (CA) as referred to in LTE Rel. 10, has required some changes from the baseline LTE Rel. 8 although each CC in LTE-A remains backward compatible with LTE Rel. 8. This article provides a review of spectrum aggregation techniques, followed by requirements on radio resource management (RRM) functionality in support of CA. On-going research on the different RRM aspects and algorithms to support CA in LTE-Advanced are surveyed. Technical challenges for future research on aggregation in LTE-Advanced systems are also outlined.

A Survey of Radio Resource Management for Spectrum Aggregation in LTE-Advanced

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)

A base station does not transmit any reference signal (RS) for channel measurement in a subframe in which transmission of an RS collides with transmission of a synchronization signal or a broadcast signal or in a resource block including the synchronization signal or the broadcast signal in the subframe. A user equipment assumes that any RS for channel measurement is not transmitted in a subframe or in a resource block when transmission of an RS collides with transmission of a synchronization signal or a broadcast signal in the subframe or in the resource block.

Method and base station for receiving reference signal, and method and user equipment for receiving reference signal

The coexistence of macro eNodeBs and the additional low power nodes (LPNs) may lead to much higher interference in LTE-Advanced Heterogeneous Networks (HetNets) In Macro Pico scenario, Range Extension (RE) is a promising scheme to utilize the LPN resources more effectively and improve the cell edge performance However, it may introduce more interference if the bias value is not properly set In this paper, an adaptive bias configuration strategy for RE is proposed In this strategy, the bias value is set adaptively according to the environment variability, which contains three stages including bias initialization, system performance feedback and dynamic bias value setting The proposed scheme aims to make the RE scheme adaptive and improve the cell edge users' performance through cell load balance Simulation results show that the proposed scheme can improve the cell edge performance compared with the static bias setting strategies, while maintaining the overall cell performance

An adaptive bias configuration strategy for range extension in LTE-advanced heterogeneous networks

In order to meet the requirement of wider bandwidth in IMT-Advanced, carrier aggregation (CA) is introduced by 3GPP to support bandwidth up to 100MHz in its LTE-Advanced standards. An LTE Rel.10 UE can aggregate up to 5 component carriers (CCs) simultaneously, but may be assigned only part of the total available CCs depending on its capability or traffic load. Thus, a proper CC selection method is necessary. First, two traditional CC selection methods respectively named Random and Round Robin CC selection are investigated, which can well balance the load across different CCs. However, neither of them is suitable for non-continuous CA scenarios through our analysis. To solve this problem, an improved CC selection method for non-continuous CA is proposed in this paper. Simulation results demonstrate that the proposed method outperforms both of the traditional ones.

Improved Component Carrier Selection Method for Non-Continuous Carrier Aggregation in LTE-Advanced Systems

The discontinuous reception (DRX) mechanism is adopted by the Third Generation Partner Project (3GPP) Long Term Evolution (LTE) as a promising technology to extend the user equipment's (UE's) battery lifetime. From our simulation, it can be found that the decrease in power consumption resulted from LTE DRX is always at the price of deteriorated system utility. Thus, this paper focuses on the design of an improved DRX configuration method to provide higher power efficiency. The single threshold adaptive configuration DRX mechanism (S-ADRX) is proposed to guarantee the system utility at the cost of extra energy consumption. Based on S-ADRX, a novel multi-threshold adaptive configuration DRX mechanism (M-ADRX) is presented, which is able to save as much power as possible while maintaining the system utility without any additional signaling overhead. Simulation results indicate that the proposed M-ADRX mechanism outperforms the current LTE DRX.

A More Power-Efficient Adaptive Discontinuous Reception Mechanism in LTE

Embodiments of the present invention include a method and base station for obtaining Channel Quality Indicator (CQI) information One embodiment of the method includes: receiving, by a base station, quantized channel information, quantization error, Inter-Cell Interference (ICI) power and noise power fed back by each User Equipment (UE) after channel estimation; and estimating, by the base station, a CQI corresponding to each UE to obtain an estimated CQI value corresponding to each UE according to the quantized channel information, the quantization error, the ICI power and the noise power which are fed back by the UE as well as an instantaneous precoding vector or matrix of each UE Through the embodiments, the base station can obtain more precise CQI information of each UE so as to select a precise modulation and coding scheme and to increase system throughput

Method and base station for obtaining channel quality indicator information

PROBLEM TO BE SOLVED: To proivde a method and an apparatus for adaptive precoding in codebook-based MIMO system. SOLUTION: The method includes the following steps: obtaining a switching threshold or a switching threshold table corresponding to the transmission space correlation according to prior values measured and obtained under different conditions; selecting and performing one or more of the following switchings according to the switching threshold or the switching threshold table in combination with the transmission correlation: switching according to user number information between a single user system and a multi-user system performed on the basis of the user numberin formation; switching between unitary precoding and ZF BF precoding; switching between a Discrete Fourier Transform codebook and a Grassmannian codebook; switching performed according to user number information between a large codebook and a small codebook. According to the present invention, switching can be made between different MIMO modes, precoding methods, codebooks and codebook size according to the change of the environment and an optimal one can be selected and adopted. COPYRIGHT: (C)2009,JPO&INPIT

Jianchi Zhu

Papers

An adaptive bias configuration strategy for range extension in LTE-advanced heterogeneous networks

Improved Component Carrier Selection Method for Non-Continuous Carrier Aggregation in LTE-Advanced Systems

A More Power-Efficient Adaptive Discontinuous Reception Mechanism in LTE

Method and base station for obtaining channel quality indicator information

Method and apparatus for adaptive precoding in codebook-based MIMO system