MULTIPLE INPUT MULTIPLE OUTPUT (MIMO)
In MIMO system there is multiple antennas is provided at the transmitter side as well as receiver side. Using multiple antennas at the transmitter and the receiver side could able to increase spectral efficiency, produces higher capacity and provides more data rates for wireless communication. In MIMO system there is SU-MIMO that is called single user MIMO in which when there is data rates need to be increased for single user then it is known as SU-MIMO, and if there is individual stream is allocated to multiple users; then it is called multiuser MIMO (MU-MIMO).
In MIMO system, let’s consider there is Mt transmitting antenna and Mr receive antennas where s= [S1, S2……SM] t is the transmitted data vector,
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Functions of MIMO
The main function of MIMO system includes precoding, spatial multiplexing and diversity coding. Precoding is the process of multi-stream beamforming which process at the transmitter. The main advantage of multi stream beamforming is to increase the received signal input, by making signals emitted from different antennas add up constructively and it is also able to mitigate the multipath fading effect. Precoding requires channel state information at the transmitter. When there is multiple antennas at the receiver, the transmit beamforming cannot simultaneously maximize the signal level at all the receive antennas, and precoding with multiple stream is used. MIMO antenna configuration is requires in spatial multiplexing. In spatial multiplexing the high rate signal is divide into low rate signals and each individual stream is transmitted from different transmit antenna which is having the same frequency channel. Spatial multiplexing is technique which is capable of increasing channel capacity at higher signal to noise
What technique used to by cable provider to enable data and voice on the same cable using different frequencies for video and data
such an IDFT operation. It is such efficient digital realization of the OFDM transmitter that
You are sacrificing a more spread out coverage area for the ability to shoot a narrow RF beam over a greater difference, lending more stability and higher possible speeds to your WLAN. Week2: Relationship Characteristics Checkpoint
Broadcasting and receiving
The paper I read is “Noncooperative Cellular Wireless with Unlimited Numbers of Base Station Antennas” written by Thomas L. Marzetta. This paper was published in IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS, VOL. 9, NO.11, NOVEMBER 2010. The pilot signal is a direct sequence spread spectrum signal continuously sending by the base station. It makes the base station could send data in the forward-link and demodulate cell phone signals in the reverse-link. The pilot signal is known as confessed, like 000000 or 111111. In frequency re-use technology, we divide the space into several cells. Due to the same or correlated pilot sequence re-use in contiguous cells, the base station will inadvertently send data to terminals in other cells or collect and combine reverse-link signals from terminals in other cells when processing. This is called pilot contamination. In this paper, the author mainly talk about the environment of multi-user(MIMO) operation with an infinite number antennas in the base station. He thinks that in this
The rake receiver uses a combination of correlators to separately detect M strongest multipath components, code generators, and delays, or “fingers”, to spread out the individual echo signals of the multipath. Each signal is then delayed according to peaks found in the received signal. The rake receiver uses several "sub-receivers" each delayed slightly in order to tune in to the individual multipath components. Each component is decoded independently, but at a later stage combined using delay compensate combiner and MRC dispreading in order to make the most use of the different transmission characteristics of each
Channel: channel means the media used to transmit to the receiver. It is important that the sender selects the best media to suit his needs and requirements. This is vital because if the wrong medium is selected then the communication won’t be that clear and once again it would be a barrier to the employees in Hirdaramani.
While allowing simultaneous access to multiple users to the medium OFDMA has been shown to reduce multi-path fading, within air interfaces in the IEEE 802.16 standard.
OFDM provides the frequency selective channel which can able to divides the frequency band into multiple sub channels and each sub channel carries a different stream of symbols. There is flat frequency response throughput each sub channel when there is narrow bandwidth of each sub channel. Therefore OFDM able to transform a frequency selective channel into set of multiple flat-fading channels. Simultaneously when M transmit antennas used an OFDM transmitter, and N receive antenna used OFDM front end then L flat fading MIMO channel is formed from MIMO frequency selective channel with having dimensions equals to MxN. Earlier traditional space time codes were not optimal for takeout the additional
(i) Multicasting Segment: It includes one entry for each recipient. The sender may broadcast the message to all the recipients or multicast some recipients. It includes:
In MIMO systems, spatial multiplexing is used for high data rate transmission and spatial diversity is used to achieve reliable communication. However, there is a tradeoff between diversity and
Once the signal is received, these receivers will demodulate the signal – meaning to extract the modulation from the received signal.
A cellular network is a radio network distributed over land areas called “cells”. Each cell is served by one fixed-location transceiver, which is called a “base station”. When cells are joined together, they provide wireless coverage over a large geographic area, within which mobile stations or phones can communicate with base stations and each other. Overlapping coverage areas allows transmission to be maintained even when mobile stations are moving between cells. Assigning a different set of frequencies to neighboring cells avoids wireless signal interference.
Broadcasting also does not require any group management. Multicasting uses group management in order to define networks where at least one host is actually interested in receiving the packet (Tech Differences). While trying to broadcast, bandwidth will be wasted. This occurs when the packet is delivered to all of the hosts even though some are not even interested in receiving that packet. Unlike broadcasting, multicasting effectively utilizes its bandwidth because the packet will only be delivered to the hosts that are actually interested in receiving the packet (Tech Differences).
Most of the case, single, small physical antenna is used (Cutrona, 1990; Kopp, 2007; Adjei-darko, 2017). A SAR image is usually 2D map which is the reflectance of the objects. It includes range dimensions and azimuth (Kopp, 2007). Most SAR uses only a single antenna for signal processing system thus monostatic. Transmitted signals are modulated pulses generated along the radar’s flight path at various positions. Pulse echo timing adjust the ranging of the system. These echo data of different positions and sequential timing are processed to the synthetic aperture length (Cutrona, 1990; Kopp, 2007). Finer azimuth resolution is possible by narrowing the array of beam pattern (Doppler processing) (Kopp, 2007).