The Infona portal uses cookies, i.e. strings of text saved by a browser on the user's device. The portal can access those files and use them to remember the user's data, such as their chosen settings (screen view, interface language, etc.), or their login data. By using the Infona portal the user accepts automatic saving and using this information for portal operation purposes. More information on the subject can be found in the Privacy Policy and Terms of Service. By closing this window the user confirms that they have read the information on cookie usage, and they accept the privacy policy and the way cookies are used by the portal. You can change the cookie settings in your browser.
This paper investigates the performance of underwater visible light communications (UVLC) systems employing multiple transmitters and/or multiple receivers to exploit the advantage of spatial diversity. Experimental results are further provided to evaluate the error performance of single input multiple outputs (SIMO), multiple inputs single output (MISO) and multiple inputs multiple outputs (MIMO)...
In this paper, codebook design for massive MIMO systems with 32/64Tx transmit branches is investigated. Using the same parameterized codebook framework of LTE Rel-13 for 16Tx, 32/64Tx codebooks are discussed and evaluated through system level simulations. In addition, to deal with the larger feedback overhead, three codebook sub-sampling methods are discussed. These methods aim to achieve a tradeoff...
In this paper, CSI feedback for massive MIMO system with planar antenna array is studied. A hybrid channel state information feedback mechanism is proposed. The proposed mechanism is based on combination of beamformed CSI-RS and non-beamformed CSI-RS transmission. Each codeword in the codebook for feedback regarding the non-beamformed CSI-RS is associated with a beamformed CSI-RS. By utilizing this...
In this paper, we propose a novel secure transmission scheme for multiple-input multiple- output (MIMO) Two-Way relay channels, where multi- pair communication partners exchange information securely with the help of relay. By utilizing the properties of transmission medium in physical layer, our scheme can achieve high transmission efficiency as well as information theoretic security. With the secrecy...
This paper deals with the pilot contamination problem for multi-cell massive multiple-input and multiple-output (MIMO) mobile communication systems. The pilot contamination effect constitutes a major bottleneck for overall performance. Most of researches on pilot decontamination ignore the fact that different users can be distinguished by the direction of arrivals (DoA), even the users in different...
Pattern reconfigurability is a desirable feature of mobile handset antennas, as it enables the antennas to adapt to non-stationary propagation environments. However, it is difficult to vary the radiation pattern of a handset antenna at frequencies below 1 GHz because the entire chassis commonly acts as the main radiator. Hence, designing pattern reconfigurability based on the antenna element (secondary...
The increased number of antennas for massive MIMO system implies that the quantization codebook size needs to be significantly larger, which increases precoder search complexity accordingly. This paper compares the vertical/horizontal channel characteristics and finds that the vertical channel has a much longer coherence time than the horizontal channel. Based on these results, a two-dimension CSI...
Evaluating SAR for multi-antennas is difficult and impractical due to the arbitrary power allocation and phase of the electric fields from different antennas causing the total field to change randomly. In this context, a simple approach was recently proposed for assessing SAR when more than one antenna is transmitting simultaneously. The metric of time averaged simultaneous peak SAR (TASPS) was derived...
In this paper, practical CSI acquisition methods for massive MIMO systems are investigated. The implementation issues of channel reciprocity based feedback in TDD are discussed, and a two-dimension feedback mechanism for FDD is proposed where the horizontal and vertical domain channels are reported separately. System level evaluation results demonstrate that massive MIMO with the two-dimensional feedback...
Designing multiple antennas in small terminals at frequency bands below 1 GHz is challenging due to severe mutual coupling among antenna elements. The severe coupling is often the result of simultaneous excitation of the fundamental characteristic mode of the terminal chassis by more than one antenna element. In this work, we propose to solve the coupling problem by manipulating the chassis structure...
Conventional antennas in single-antenna terminals that resonate at frequencies lower than 1 GHz usually rely on the chassis as the main radiator. To effectively exploit chassis excitation for MIMO terminals, each of the multiple antennas is required to excite one distinct chassis mode. However, in today's terminals, there is typically only one chassis mode that can radiate efficiently at frequencies...
In this paper, we perform transmit antenna selection to improve the energy efficiency of large scale MIMO systems. We first derive a good approximation of the distribution of the mutual information in this antenna selection system. It shows that channel hardening phenomenon is still retained as full complexity with a large number of available antennas, though the number of actually used antennas can...
In this paper, we consider K-user multiple input and multiple output (MIMO) Y channel where each user is equipped with M antennas and the relay N antennas. A scheme that each user exchanges d pairs of messages with each of the other users simultaneously via an intermediate relay is proposed. It is accomplished by utilizing signal space alignment for network coding and interference nulling beam forming...
A new multi-user two-way transmission network is considered to fully utilize wireless system resource, and ensure transmission reliability, with assistant of an amplify-and-forward relay. In multiple access channel (MAC) phase, signal space alignment technique is employed, which cancel the multi-user interference. In broadcast channel (BC) phase, a new multiple-input multiple-output (MIMO) precoding...
This paper proposed an adaptive codebook design method based on codebook rotation, without changing the existing base matrix of the codebook,and according to the statistics and estimation results of the BER and SINR, to generate a new set of rotation matrix codebook. Moreover, combing with the overhead of the feedback and the original base codebook matrix, to constitute a matrix of pairs of codebook...
A time-frequency synchronization method using shift-orthogonal constant amplitude zero auto correlation (CAZAC) sequences constructing the synchronization preamble is designed for multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) shortwave systems. The timing synchronization and integral frequency offset is accomplished by using the good correlation properties...
The inhabited environments are MIMO, uncertainly, and nonlinear complex systems. This paper presents a novel intelligent fuzzy agent(IFA) based on input-output associational algorithm for intelligent inhabited environments. An input-output dynamic associational algorithm based on Hebb learning is proposed, which can divide a complex system into multiple simple systems and eliminate the irrelevant...
In this work, we present a built-in filter method to enhance the isolation level between closely packed MIMO antennas. The built-in filter is composed of several slits etched on the ground of the antenna structure. The number and length of slits depend on both the resonance frequency and the structure of the MIMO antenna system. To illustrate its usefulness, two designs of compact planar four-port...
In this paper, an iteration interference cancellation detector for multi-user MIMO uplink transmission system is proposed, which utilizes the special property of Orthogonal Space Time Block Code(OSTBC) equivalent channel of each user to simplify the decoding at the base station. With the proposed algorithm the number of receive antennas is significantly reduced as much as the number of users, and...
Set the date range to filter the displayed results. You can set a starting date, ending date or both. You can enter the dates manually or choose them from the calendar.