Wireless Network Concepts

Running head: WIRELESS NETWORK CONCEPTS
Wireless Network Concepts
[Name of the Student]
[Name of the University]
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Q1. Why is spread spectrum transmission used? Comparison between two common methods
used for spread spectrum transmission.
Ans. Spread spectrum refers to the form of wireless communication where the transmitted
signal’s frequency is varied deliberately, which ultimately results in the formation of a
bandwidth which is much greater than the bandwidth which the signal would be having when the
frequency was not varied. The signal transmitted occupies a much higher bandwidth than the
systems which are used in the conventional modulation methods (Torrieri, 2015). The spreading
of the band is achieved my selecting waveforms of appropriate bandwidth which generally
consists of waveforms with wide bandwidth. One of the most popular way is by multiplying the
data signals of the user with a fast code sequence and this is mostly independent of the data
message which has been already transmitted (Rappaport et al., 2013). For this case the radio
portion that is shared by the users is same but the code used is different so as to distinguish the
transmissions made by them.
There exists mainly methods for implementation of multiple access and they are namely
FDMA or Frequency Division Multiple access, TDMA or Time Division Multiple Access and
lastly CDMA or Code Division Multiple Access.
Time Division Multiple Access is the method which generally comes under the process
of modulation. This method is associated with providing of users at a larger rate so as to access
the single radio frequency channel or RF channel without the involvement of any type of
interference and is associated with allocating each user with an independent time slot (Sha, Qiu
& Mei, 2012). In this method different types of users communicate with each other which means
listening and speaking in accordance to the time slots that has been allocate to them. It is mainly
used in the digital cellular telephones and is associated with dividing each and every cellular

channels into three time slots for the purpose of increase the data that is to be carried. TDMA
was firstly identified as the standard in the EIA/TIA Interim Standard 54 or IS-54. This later
evolved to Interim Standard-136 or IS-136 and is used by US standards for the TDMA for
cellular as well as the personal communication services spectrum which is having an frequency
of around 850MHz and 1.9GHz.the TDMA is also used for the DECT or Digital Enhances
Cordless Telecommunication. The mobile stations radio components are allowed to listen and
broadcast by the TDMA only in the time slot assigned to them. Along with this during rest of the
time the mobile stations might apply the network measurements by the detection of the different
transmitters that surrounds it having different frequencies.
Code Division Multiple Access generally refers to the different types of protocols which
are generally used in the second generation or 2G and the third generation or 3G wireless
communication. According to the term it can be stated that is one of the form of multiplexing and
is generally associated with allowing several signals to occupy a single channel responsible for
transmission. This also optimizes the use of the bandwidth which is available. This technology is
generally used in the ultrahigh frequencies cellular telephone system which has a frequency
range of around 899MHz and 1.9 GHz. Conversion of the analog to digital signal is also
employed by the CDMA (Kaddoum, Richardson & Gagnon, 2013). This is associated with
sharing of the channels for the purpose of transmitting information of different type which is
generally having a definite RF bandwidth which is mainly associated with the other users
instantaneously and also with the interference of each other. This is initially responsible for
providing flexibility at larger amounts and overall system capacity which is high with respect to
the Cellular systems. Each digital packet in the CDMA is sent along with a unique key and the
responsible receiver which possess the key to that code is capable of picking up those signals

quickly and then demodulate that for this reason a special type of coding scheme is followed in
order to allow numerous users to be multiplexed over same channels.
Fig 1: CDMA Spread Spectrum Generation
Fig 2: CDMA Spread Spectrum Decoding
Q2. Different components of a radio system. What are different mixers? Explain different types
of Mixers with diagram?
Ans: Different types of radio components are available for appropriate platform installation
(Sadegh Amiri et al., 2013). The different components of a radio spectrum are listed below:
 Filter and Multi-coupler
 Power amplifiers
 Antenna tuning units
 Remote control units
 Power suppliers