Spatial Multiplexing In 4G Wireless Communications

Spatial Multiplexing In 4G Wireless Communications

4G Communications

Introduction:

availability of radio frequency spectrum and transmission problems
caused by such factors as fading and multipath distortion. Meanwhile, there is increasing demand for higher data rates, better quality service, fewer dropped calls, and higher network capacity. Meeting these needs requires new techniques that improve spectral efficiency and network links‘ operational reliability. Multiple-input-multiple-output (MIMO) technology promises a cost-effective way to provide these capabilities. 

MIMO technique is able to:

High data rate wireless communications links with transmission rates nearing 1 Gigabit/second.

Good Quality of Service (QoS)
Used to increase spectral capacity.
Use method called spatial multiplexing to transmit data streams
Using MIMO in any system as CDMA and whatever there is a lot of flexibility

How we get on high data rate?

Shannon’s Capacity (C)

Given a unit of BW (Hz), the max error-free transmission rate is

C = W log2 (1+SNR) bits/s/Hz ,W: allotted BW (Hz)

Spatial Multiplexing:

Spatial multiplexing offers a linear increase in the transmission rate 

(or capacity) for the same bandwidth and with no additional power expenditure. Spatial multiplexing allows transmitting different streams of data simultaneously on the same resource block(s).

a)V-BLAST–Spatial-Multiplexing

(Vertical Bell Labs Layered Space-Time Architecture):

This is the only architecture that goes all out for maximum rate. Hope the 

channel helps me out by ‘splitting’ my info streams.

b)D-BLAST– a little-of-both

(Diagonal Bell Labs Layered Space-Time Architecture):

In D-BLAST, the input data stream is divided into sub streams which are

coded, each of which is transmitted on different antennas time slots in a diagonal fashion

Comparison

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