Optimal Linear Transmit Beam Forming Techniques for Multi-User MIMO (original) (raw)

Effective Beamforming Technique Amid Optimal Value for Wireless Communication

Electronics

In the notion of communication system resource provision specifically, beam-forming is a concept of proficient utilization of the power of transmission. Network densification and massive MIMO allows us to control the power efficiency and can be effectively distributed among different users by reducing cost. We presented a practical scenario for the performance of massive MIMO and multi-small cell system to analyze the overall performance of the system. Our work is based on the resource allocation with optimal structural constraints to maintain the cost effectiveness while considering economic implications. The base stations located far away from the users receive attenuated signals and give rise to path loss, whereas the problems of inter cell interference also arise due to transmission from a base station to others cells. The performance of the cellular system can be enhanced with the combination of massive Mimo and small cells, where we simulate and also provide an analysis on pra...

On the Pareto-Optimal Beam Structure and Design for Multi-User MIMO Interference Channels

IEEE Transactions on Signal Processing, 2013

In this paper, the Pareto-optimal beam structure for multiuser multiple-input multiple-output (MIMO) interference channels is investigated and a necessary condition for any Pareto-optimal transmit signal covariance matrix is presented for the K-pair Gaussian (N, M 1 , • • • , M K) interference channel. It is shown that any Pareto-optimal transmit signal covariance matrix at a transmitter should have its column space contained in the union of the eigen-spaces of the channel matrices from the transmitter to all receivers. Based on this necessary condition, an efficient parameterization for the beam search space is proposed. The proposed parameterization is given by the product manifold of a Stiefel manifold and a subset of a hyperplane and enables us to construct a very efficient beam design algorithm by exploiting its rich geometrical structure and existing tools for optimization on Stiefel manifolds. Reduction in the beam search space dimension and computational complexity by the proposed parameterization and the proposed beam design approach is significant when the number of transmit antennas is larger than the sum of the numbers of receive antennas, as in upcoming cellular networks adopting massive MIMO technologies. Numerical results validate the proposed parameterization and the proposed cooperative beam design method based on the parameterization for MIMO interference channels.

Multiuser Downlink MIMO Beamforming Using an Iterative Optimization Approach

2006

Multiple antennas at the transmitter and the receiver have the potential to either increase the data rate through spatial multiplexing or enhance the quality of transmission through exploitation of diversity. In this paper, we address the problem of multi-user multiplexing using spatial diversity techniques for a MU-MIMO-OFDM system so that a basestation could serve multiple users in the same frequency band making huge saving in bandwidth utilization. In particular, we have proposed various techniques to improve substantially the performance of a recently proposed signal-to-leakage maximization based algorithm. Our simulation results reveal a lower error floor and improvement in BER performance and system throughput for various coding rates.

Joint Beamforming and Power Control In Downlink Multiuser MIMO Systems

ece.odu.edu

In this paper we discuss joint beamforming and power control for downlink multiuser MIMO systems with target signal-to-interference+noise ratios (SINR) constraints. We derive necessary conditions for minimizing total interference at downlink receivers and present an algorithm which adapts the beamforming vectors and powers incrementally to meet specified SINR targets with minimum powers. The proposed algorithm is illustrated with numerical examples obtained from simulations.

INTERFERENCE SUPPRESSION IN MULTIUSER DOWNLINK MIMO BEAMFORMING USING AN ITERATIVE OPTIMIZATION APPROACH

2006

Multiple antennas at the transmitter and the receiver have the potential to either increase the data rate through spatial multiplexing or enhance the quality of transmission through exploitation of diversity. In this paper, we address the problem of multi-user multiplexing using spatial diversity techniques so that a base station could serve multiple users in the same frequency band making huge saving in bandwidth utilization. In particular, we have proposed various techniques to improve substantially the performance of a recently proposed signal-to-leakage maximization based algorithm. Our simulation results reveal a lower error floor and more than 10 dB improvement in BER performance.

Resource allocation for QoS multiuser MIMO with zero forcing and MMSE beamforming

2010 IEEE 18th International Workshop on Quality of Service (IWQoS), 2010

To enable ubiquitous end-to-end quality of service over IP networks expanding to rural areas, we examine resource allocation problems of a MAC layer for an OFDM MIMO wireless base station (BS) using multiuser beamforming. We compare two linear beamforming techniques, zero-forcing (ZF-BF) and minimum mean square error (MMSE-BF). To guarantee minimum bandwidth and low packet delay in an environment where the number of users is much larger than the number of BS antennas, one needs to partition the users into several sets and combine space division multiple access (SDMA) with time division multiple access (TDMA). We study the impact on the optimal transmission power resulting from selecting the following design parameters: (i) ZF-BF vs. MMSE-BF; (ii) the number of user sets multiplexed by TDMA; and (iii) the number of BS antennas. Two notable results are observed: (1) power wise, ZF-BF is far more superior to MMSE-ZF; (2) substantial power can be saved by increasing the number of BS antennas; however, only by large increments, e.g., from 6 to 9 and further to 21.

An Overview on Resource Allocation Techniques for Multi-User MIMO Systems

IEEE Communications Surveys & Tutorials, 2017

Remarkable research activities and major advances have been occurred over the past decade in multiuser multipleinput multiple-output (MU-MIMO) systems. Several transmission technologies and precoding techniques have been developed in order to exploit the spatial dimension so that simultaneous transmission of independent data streams reuse the same radio resources. The achievable performance of such techniques heavily depends on the channel characteristics of the selected users, the amount of channel knowledge, and how efficiently interference is mitigated. In systems where the total number of receivers is larger than the number of total transmit antennas, user selection becomes a key approach to benefit from multiuser diversity and achieve full multiplexing gain. The overall performance of MU-MIMO systems is a complex joint multi-objective optimization problem since many variables and parameters have to be optimized, including the number of users, the number of antennas, spatial signaling, rate and power allocation, and transmission technique. The objective of this literature survey is to provide a comprehensive overview of the various methodologies used to approach the aforementioned joint optimization task in the downlink of MU-MIMO communication systems.

Random Beamforming for Spatial Multiplexing in Downlink Multiuser MIMO Systems

2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications, 2005

Optimization of beamforming in broadcast MIMO channels is severely hampered by the amount of feedback. In this paper we propose to reduce the feedback when employing a random beamforming where multiple streams can be linearly precoded before being transmitted on the antenna array and the users with channel/interference matched to the beamforming configurations are scheduled at each time. In MIMO system the users can further improve the overall throughput by minimizing the inter-stream interference. The feedback necessary to employ the spatial multiplexing can be limited to the signal to interference ratios for a sub-set of users that are compatible for the random beamforming configuration. In spite of the simplicity, this scheduling strategy can take advantage of the multiuser diversity for a large number of independent channels (or users) as in OFDMA system. The numerical analysis validate the strategy for the selection of compatible users and the spectral efficiency for this opportunistic spatial multiplexing scheme.

User selection schemes for maximizing throughput of multiuser MIMO systems using Zero Forcing Beamforming

2011

The performance of a multiuser MIMO broadcast system depends highly on how the users being served are selected from the pool of users requesting service. Though dirty paper coding can obtain the optimal capacity of multiuser MIMO Broadcast systems, the computational complexity is high. We examine this problem in the context of systems using Zero Forcing Beamforming (ZFBF) which have low complexity and reasonable throughput. The channels of the selected users may not be orthogonal to each other resulting in harmful interference and reduction in the performance of the system. This work identifies and thoroughly investigates the main factors affecting the performance and proposes some mitigating schemes to fully exploit multiuser diversity. In particular, we develop improved user selection schemes designed to maximize the sum rate that offer a range of complexity to performance tradeoff. Simulation results show that the selection schemes developed compare favorably with existing techniques.