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OFDM is a most attractive fast growing multi-carrier modulation technology enabling high capacity of data transmission over a single path. The major problem in OFDM is its high peak-to-average power ratio with respect to independent subcarrier. Transmitter containing non-linear components distorts the signal due to presence of large PAPR there by increasing the complexity and reducing the efficiency...
This paper explores limited feedback nullforming techniques based on random vector quantization (RVQ) with and without receiver coordination. The availability of receiver coordination affects the type and amount of feedback required to select an appropriate precoding vector. Approximate upper and lower bounds are developed for the mean received power at primary receivers with and without receiver...
We study and analyze coverage region for MIMO amplify-and-forward (AF) relay network. We consider the network geometry in which L relays are placed uniformly around the source, and assume that there is no direct link between source and destination. We analyze desired transmission rate with the purpose of maximizing coverage region. Using Monte Carlo simulations the impact of number of transceiver...
A 4-elements PIFA array antenna is designed for the laptop Wi-Fi application. The proposed array antenna elements are optimized for 2.45 GHz. It is a wide band antenna. It is embedded on the back side of the laptop screen. These array elements are excited simultaneously. The performance of this antenna is analyzed and the interaction between this antenna array and user (phantom) of the laptop is studied...
A novel scheme of unitary space-time constellations generation based on zero vectors adding are proposed for the multiple-antenna communication system. In the scheme, T2 zero row vectors are added into conventional unitary matrices directly, and the number of new unitary matrices obtained by different positions of the added zero vectors in T symbol duration is ⌊T/T2|⌋ times larger than that of conventional...
Long Term Evolution (LTE) is a standard for wireless communication of high speed data for mobile phones and data terminals. LTE is capable of delivering large data rate on the order of several megabits per second, which is even larger than the current 3G systems. This is very challenging as the wireless networks are subjected to interference, multipath and poor propagation channel characteristics...
This paper addresses the designing a pragmatic appliance of multi-antenna, 2.437GHz ISM band multiple-input multiple-output (MIMO) testbed systems developed for evaluating wireless MIMO algorithms. Since using Sundance demo package for the development of a flexible field-programmable gate array (FPGA) processing system. The objective of this contribution is to provide an understanding of basic MIMO-LTE...
In this paper, we elaborated on a new interference alignment technique for downlink multi-user system in a MIMO-X channel with multiple antennas. We considered two transmitters, each equipped with M antennas, and L users, each equipped with K antennas. Here, we consider a MIMO-X scenario that some users are receiving transmissions from both transmitters. The proposed approach is focused on rank-1...
In this paper, we present a method which jointly performs robust channel estimation and signal detection over rank-deficient MIMO links. This technique achieves an excellent estimation of the channel matrix by using all detected symbols within a data frame. Symbol detection is achieved by means of a sphere decoding algorithm. The proposed scheme is equivalent to having the training preamble occupy...
Sparse space codes (SSC) are proposed as a novel transmission scheme for an under-determined MIMO channel. Each SSC codeword is a sparse vector of the size of the number of transmit antennas. The information is imparted through: (i) uncertainty in the positions of non-zero elements, and (ii) uncertainty in the symbol-space of non-zero elements. Basis-pursuit (BPD) and LASSO detectors are used with...
This paper investigates the performance enhancements using radio-frequency (RF) beamforming on closely spaced antennas in multiple-input multiple-output (MIMO) communication system. Of specific interest is the case of a array of extremely closely spaced antennas with complexity constraints, here implemented being restricted to a single RF chain. Our system model is developed in context of closely...
In this paper, the information extracted from Single-Input Multiple-Output sounding measurements is used to study the effect of several aspects of the receive antenna arrays on system performance. The extracted multipath parameters are used to synthesize the MIMO channel matrices of a hypothesized communication system having a fixed microcellular base-station and a handheld terminal moving throughout...
Multiple input multiple output (MIMO) communication architecture has spectral efficiencies far beyond those offered by conventional techniques, and is greatly to increase the channel capacity. In this paper, we investigate the MIMO channel capacity in correlated channels using the uniform angular distribution, numerical simulations are performed with Matlab to verify the proposed formula. We prove...
MIMO antenna design is one of biggest issues in the LTE deployment. The multiple antennas should be designed compactly without sacrificing radiation efficiency and spatial correlation. Such multiple antennas can be achieved with polarization antennas or decoupling elements. Conventionally, these antenna parameters are designed empirically. In this paper, a method to optimize multiple antenna directivities...
The compactness of mobile terminals complicates the design of multiple antennas, since coupling among the antennas increases when they are placed in proximity of one another. While it is possible to mitigate coupling between closely spaced antennas, a tradeoff in bandwidth is required. In this paper, we highlight ground plane excitation as an additional dimension to consider in the design of multiple...
This paper presents the method to minimize the inter-element mutual coupling in a pair of suspended plate antennas by optimization of the orientation and feed configuration of antenna elements. By reducing the interelement mutual coupling, the envelope correlation coefficient can be suppressed for multiple-input multiple-output (MIMO) antenna systems.
In this paper, a Multi-Input Multi-Output (MIMO) antenna is proposed. The isolation characteristic of proposed MIMO antenna between two radiating elements is improved by using a Split Ring Resonator (SRR) array structure. The fabricated antenna satisfied the 10 dB return loss requirement and the isolation between the two radiating elements was higher than 15 dB in the Mobile-WiMAX frequency band....
Planar Inverted F Antennas (PIFAs) are commonly used in portable applications due to their attractive features. There exists a huge demand to use these PIFAs as MIMO or diversity antennas to allow for an increase in data rates or signal quality and to combat the shallow fading minima that exist in a multipath propagation environment with a non line of sight path. Recently, two new single element dual...
The handling of the radio channel is an important aspect that determines the working capability of a mobile communication system. Since the channel behavior is influenced by the environment, which leads to a different behavior in different environment, the antenna design (synthesis) becomes environment dependent (time-variant) as well. In this paper, a capacity maximizing approach to design antenna...
Being an important wireless communication technique, multiple input multiple output (MIMO) system can effectively increase channel throughput by spatial multiplexing. However, the performance of a MIMO system can be further improved through adaptive modulation and intelligence antenna techniques. The affiliation of a controller can save power and diminish mechanical consumption with a guaranteed bit...
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