FREQUENCY DIVISION MULTIPLE ACCESS

Jun 23 • Notes • 3509 Views • 1 Comment on FREQUENCY DIVISION MULTIPLE ACCESS

 

Frequency Division Multiple Acess

Frequency Division Multiple Access

 

 

 

 

 

FREQUENCY DIVISION MULTIPLE ACCESS

FREQUENCY DIVISION MULTIPLEXING

The Frequency division multiple access also known as  FDMA  are basically a medium access method used for multiple access program as a channelization protocol.

An individual allocation is given to the uses having one or many frequency bands by the FDMA.

The FDMA as stated as Frequency division multiple access is particularly a hub in the satellite communication system as the multiple access sub system which has a multiple use for the coordination access.

Many other types of multiple access systems are TDMA, CDMA as well as the SDMA.

These are the protocols which have different functions at different levels according to the OSI model.

The FDMA protocol has a disadvantage which is due to the crosstalk basically is the reason for the interrupted transmission network.

Another disadvantage of the FDMA is that even if there is a facility to share the satellite communication by the users, it can transmit one user at a single frequency.

The FDMA system also has filters which has tremendous performance and is used for radio hardware the FDMA is not exposed towards problems related to time but TDMA has this issue.

The time slot gives a facility of having multiple station and can avail sharing of similar transmission medium with a single channel capability.

The TDMA has various applications and one of its most important application is the digital 2G cellular system for example the GSM,IS-136,PDC and also the I DEN which is vital part of digital enhanced cordless. The most vital application of TDMA is in the field of telecommunication used for portable phones.

The sensitivity of FDMA towards the near-far problem is very less which is due to the frequency filtering and every user get a unique code having its unique frequency set.

TIME DIVISION MULTIPLE ACCESS

The TDMA is a mode access method which is used for networks in the medium range. The pros of the TDMA network is that it can be used to be many users and can share between the same range of frequency, it does so by dividing the range of the frequency into different time intervals and the time slot provided to each user varies rapidly according to limit of time provided.

CODE DIVISION MULTIPLE ACCESS

The CDMA is a mode access method used for the radio communication methods or the radio series. These cannot be used for the mobile communication range which is CDRNA One, CDMA 2000 as well as the WCDMA which is now called CDMA and this is basically used as the channel feasibility method.

The CDMA has the approach to allow many transmitters to transmit the message to several users at the same time. And the same frequency band is used at the same time by all the users which is why it is called multiple access.

ETHERNET

Combination of different channels of computer networking technology is known as Ethernet.

Ethernet was first found in 1980 and the standardized in the year 1985 as said by IEEE 802.3.

But presently Ethernet has a substitute having better pros the LAN system. As the Ethernet system consist of various wirings having a span of OSI physical layer.

The sharing medium is accessed by the coaxial is wires or cables.

After further technological advancement these coaxial pairs are replaced by twisted ones and later new links that are the fiber optic links having hubs and switches.

The data rate of this system rises from 10 megabits per sec to 100 gigabits per sec.

A shorter span of the data division takes place in case of the system communication of Ethernet.

This means that the single span of data is divided into shorter spans called the frames.

And these frames contain both the source address as well as destination address.

These frames also contain the error checking data’s too.

There error checking data’s facilitate the error checking by checking the data’s if problem persist then the data’s are retransmitted. The data link layer of the OSI model includes the services provided by Ethernet.

Ethernet persist of good span of compatibility featured as 48 bit addressability against MAC.

These have influence the other protocols to further technical advancement.

FAST ETHERNET

It is one of the technical advancement of Ethernet and has a natural capability to carry the traffic that is a rate of 100 M bits/s which is 10 times higher than the original Ethernet is used by the year 2010.

 

ADDRESSING MECHANISM

The internet addressing mechanism comprises of message fragmentation i.e. it means sedimenting of messages for the carrying three messages to object.

This mechanism is usually encompassed by

  1. Contexts:  the context is a logical bucket space which comprises of objects existing together in a single memory providing they have an effective communication between them.
  2. Handle: this basically denotes and intimates effective transfer of the data’s as the endpoint address of any message denotes the handle which is always specific. The combination of the class and handle is a message known as static message.

PHYSICAL LAYER

The OSI model consists of 7 layers and out of which the physical layer is considered the first one and is termed as PHY. The initial concepts are networking transmission technologies are used in case of the physical layer.

The physical layer is not economical in use due to unavailability of varying hardware technologies. The work of the physical layer is transmission of raw bits but has a transmitted the logical data packets.

The method of transmission of the raw bits is by converting them into data code by grouping certain bits into code word. These code words or symbols are then converted

GIGABIT ETHERNET

The Ethernet frames that transmit data’s at a rate of gigabit per second is called gigabit Ethernet. If first came into existence in the year 1999 and then converted in the form of simple wired connections having faster accessibility. The gigabit Ethernet has better speed and economical to the signal known as the physical signal and this physical signal uses the hardware transmission system as the mode of channel to transmit the codes.

The transmission of the codes be done in the electrical or mechanical medium also.

RADIO LAYER

A radio layer is an interfacing unit towards the hardware such as radios and modem. It is basically considered to be an operating system having a span of varieties like –

  1. Android layer
  2. Mobile layer
  3. Windows layer

 

 

BASE BAND LAYERS

Any signal having a range of 0 hertz to the cut-off-frequency is considered as the base band layer.

This is also considered as a low pass signal or non-modulating signal.

LOGICAL LINK CONTROL AND ADOPTION PROTOCOL (L2CAP)

The layer present above the base band layer is the logical link control and adoption protocol layer. It is a resident of the data link layer.

It has the ability to provide accessibility to service to both connectionless data and the connection oriented data.

QUESTION AND ANSWER

Q1. What are the organizations involved in standard creation committee?

Ans:  1. ISO

2. ITU-T

3. ANSI

4. IEEE

5. EIA

Q2. What do you refer ISOC as?

Ans : internet society is the reference protocol for ISOC.

Q3. Who is IAB?

Ans : internet architective board.

Q4. Why do we need proxy?

Ans:  proxy is a type of pc which keeps responses recent request of the present settings.

GATE Syllabus-

1. Gate syllabus for Electronics and Communication Engineering

IES Syllabus-

1. IES Syllabus for Electronics and Telecomm

2. IES Syllabus for General Ability

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