Question 1: The spectral efficiency of a transmission scheme, denoted as h is de

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Question 1: The spectral efficiency of a transmission scheme, denoted as h is defined as the data rate that can be supported in 1 Hz of bandwidth and it is measured in bps/Hz. Show how you will calculate the spectral efficiencies of all of the 2G cellular systems and the early wide area data systems discussed in class.

Question 2:Consider a CDMA system with three users – Alice, Bob, and Cara. They are assigned the following orthogonal codes respectively: [1 1 1 1], [1 -1 1 -1] and [1 -1 -1 1]. Alice sends two zeros, Bob sends a zero and a 1 and Cara sends a one and a zero. Show the composite baseband signal if all three users are perfectly synchronized. Assume NRZ signaling with a chip duration of 1 s

Explanation / Answer

1.

Spectral efficiency, range proficiency or data transfer capacity productivity alludes to the data rate that can be transmitted over a given transmission capacity in a particular correspondence system.It is a measure of how productively a constrained recurrence range is used by the physical layer convention, and now and then by the media get to control (the channel get to convention).

The link spectral efficiency :

The link spectral efficiency of a computerized correspondence framework is measured in bit/s/Hz,or, less often yet unambiguously, in (bit/s)/Hz.It is the net bitrate (valuable data rate barring blunder amending codes) or greatest throughput separated by the transmission capacity in hertz of a correspondence channel or an information link.Alternatively, the ghostly proficiency might be measured in bit/image, which is comparable to bits per channel utilize (bpcu), suggesting that the net piece rate is partitioned by the image rate (balance rate) or line code beat rate.

Connection ghastly proficiency is ordinarily used to dissect the productivity of a computerized balance strategy or line code, here and there in mix with a forward blunder amendment (FEC) code and other physical layer overhead.In the last case, a "bit" alludes to a client information bit; FEC overhead is dependably excluded.The tweak effectiveness in bit/s is the gross bitrate (counting any mistake rectifying code) separated by the data transfer capacity.

Illustration: A transmission procedure utilizing one kilohertz of transfer speed to transmit 1,000 bits for every second has an adjustment productivity of 1 (bit/s)/Hz.

Area spectral efficiency:

In advanced remote systems, the framework phantom productivity or Area spectral efficiency is commonly measured in (bit/s)/Hz per unit range, in (bit/s)/Hz per cell, or in (bit/s)/Hz per site.It is a measure of the amount of clients or administrations that can be at the same time bolstered by a restricted radio recurrence data transfer capacity in a characterized geographic area.It may for instance be characterized as the most extreme collected throughput or goodput, i.e. summed over all clients in the framework, partitioned by the channel bandwidth.This measure is influenced by the single client transmission procedure, as well as by different access plans and radio asset administration strategies utilized.It can be significantly enhanced by powerful radio asset management.If it is characterized as a measure of the greatest goodput, retransmissions because of co-channel impedance and crashes are excluded.Higher-layer convention overhead (over the media get to control sublayer) is ordinarily disregarded.

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