TCP/IP reference model has four layer They are Network Interface layer, Network layer, Transport layer and Application layer.
(1) Network Interface layer:
1. It is the bottom most level layer. It is comparable are being used in this to that of the OSI physical and data link layers. Different TCP/IP protocols are being used in this layer.
2. Ethernet and Token Ring for LAN
3. x - 25, frame relay, and ATM for wide area networks (WAN)
4. It is assumed to be an unreliable layer.
(2) Network layer:
1. It is the layer where data is addressed, packaged, and routed among networks.
2. Protocols are: Internet protocol, address resolution protocol, Internet control/message protocol,
3. Internet Group management protocol.
Internet Protocol: (IP)
1. Routable protocol which uses IP addresses to deliver packets. It is an unreliable protocol, does not guarantee delivery of information.
2. Address Resolution Protocol (ARP)
3. Resolves IP address to MAC addresses ie, map IP network addresses to the hardware addresses.
4. Internet Control Message Protocol (ICMP):
5. Used by network devices to send error messages and operational information.
6. Internet Group Management Protocol (IGMP)
7. It is a communication protocol used by hosts and routers to send multiple IP address at once.
(3) Transport layer:
1. The sessions are recognized and data packets are swapped between hosts in this layer. Two main protocol are.
2. Transmission Control Protocol (TCP): provides reliable connection oriented transmission between two hosts, It ensures delivery of packets between the hosts.
3. User Datagram Protocol (UDP): provides connectionless, unreliable, one to one, one to many delivery.
(4) Application layer:
1. It is similar to session, presentation and application layers of the OSI model. The application protocols are
2. Hyper Text Transfer Protocol (HTTP): The core protocol of the world wide seb.
3. File Transfer Protocol (FTP): enables a client to send and receive complete files from a server
4. Telnet: Connect to another computer on the Internet
5. Simple Mail Transfer Protocol (SMTP): provide email services,
6. Domain Name System (DNS): Refer to other host computers by using names rather than numbers.

Merits:
1. It operated independently
2. It is scalable.
3. Client/server architecture.
4. Supports a number of routing protocols.
5. can be used to established a connection between two computers.
Demerits:
1. Transport layer does not guarantee delivery of packets.
2. The model cannot be used in any other application.
3. Replacing Protocol is not easy.
4. It has not clearly separated its services, interfaces and protocols.

TCP/IP:
(i) Transmission Control Protocol/Internet Protocol, TCP/IP is a set of protocols which governs communications among all computers on the Internet. TCP/IP protocol tells how information should be packaged. sent, and received, as well as how to get to its destination.
(ii) TCP WORKING: TCP/IP is a combination of two protocols: Transmission Control Protocol (TCP) and Internet Protocol (IP).
(iii) The Internet Protocol typically specifies the logistics of the packets that are sent out over networks; it specifies the packets which have to go, where to go and how to get there.
(iv) The Transmission Control Protocol is accountable for guaranteeing the trustworthy transmission of data. It checks if any packet is not transmitted and submits it again.
Frequent TCP/IP Protocols :
(i) HTTP - It is used between a web client and a web server and it guarantees non-secure data transmissions.
(ii) HTTPS – It is used between a web client and a web server ensures secure data transmissions.
(iii) FTP - It is used between computers for sending and receiving file.
Domain Names and TCP/IP Addresses :
The address for any website is not as easy as to remember, domain name are used instead. For example, 216.58.216.164 is one of the IP address for Google and google.com is the domain name.

RFID stands for Radio Frequency Identification, RFID uses RF wireless technology. RFID used for radio waves to read and capture information stored on a tag attached to an object. Tag can be read from several feet away and does not need to be in direct line of sight of the reader to be tracked. RFID has been made up of two parts a reader and tag or a label. RFID tags are installed with a transmitter and a receiver. RFID component on the tags has two parts: a micro which stores and processes the information, and the antenna to receive and transmit a signal. The tag replies the information from its memory bank. The reader will transmit to read the result to RFID computer program.
There are two types of RFID system
(i) Active RFID
(ii) Passive RFID
(i) Active RFID system: The tag has its own power source. These systems used for larger distances and to track high value goods like vehicles.

(ii) Passive RFID system: The tag gets power through power from a reader antenna to the tag antenna, they are used for shorter range transmission.
1. Passive RFID tag will induced the reader to receive radio wave energy and restored the information back to the reader.
2. Battery powered RFID tag is installed with small battery that powers the broadcast of information.

Wi-fi stands for wireless fidelity. It is a wireless network technology that permits computers and alternative devices to be connected to every alternative in to a local area network and to the net without wires and cables. Wi-fi uses radio frequencies for data transmission. wi-fi is additionally stated as wireless local area network that stands for wireless local area network and 802.11 that is that the technical code for the protocol.
Advantages:
(i) It provides mobility
(ii) It provides connection to internet
(iii) Flexibility of LAN
(iv) Ensures connectivity
(v) It allows places that are remote to benefit from connectivity
(vi) Low cost, high benefits

(i) SG is the stage succeeds the 4G (LTE/WiMAx), 3G(umts) and 2G(GSM)syetems.
(ii) SG targets to performance the high data rate, reduced latency, energy saving, cost reduction, higher system, capacity, and massive device connectivity.
(iii) The two phasesof SG,First one will be Release-1S complete by March 2019, Second one Release- 16is expected to complete at March2020, for submission to the ITU (International Telecommunication Union) as a candidate IMT- 2020 technology.
(iv)  The ITU IMT - 2020 provides speeds up to 20 gigabits per second it has been demonstrated with millimeter waves of lS giga hertz and higher frequency. 3 GPPstandards includes any network using the New Radio software. SGNew Radio can accessat lower frequencies from 600 MHzto 6 GHz.
(v) Speed in the lower frequencies are only modest higher than 4G systems, estimated at lS% to SO%faster

 (i) 4G is at the research stage. 4G was based on an adhoc networking model where there was no need for a fixed infrastructure operation.
(ii)  Adhoc networking requires global mobility features (e.g. Mobile IP) and connectivity to a global IPv6 network to support an IP addressfor each mobile device. Logicallyroaming in assorted IP networks (for example: 802.11 WLAN,
(iii) GPRSand UMTS) were be possible with higher data rates, from 2Mbit/s to 10-100Mbit/s, offering reduced delays and newly services.
(iv) Mobile devices will not expect on a fixed infrastructure, they will require enhanced intelligence to self-configure in adhoc networks and having routing capabilities to route over packets switched network.

(i) Third generation of mobile systems merges different mobile technology standards, and uses higher frequency bands for transmission and Code Division Multiple Access to delivery data rates of up to 2Mbit/s supports multimedia services (MMS: voice, video and data) .
(ii) European standard is UMTS(Universal Mobile Telecommunication Systems).
(iii)  Mobile phones systems continue to use digital transmission with SIM authentication for billing systems and for data incorruption.
(iv) Data transmission used a WCDMA. WCDMA stands for (Wideband Code Division Multiple Access).
(v) One technique to obtain data rates between 384kbit/s and 2048kbit/s. Few 3G suppliers use ATM (Asynchronous Transfer Mode) for their 'over the air' network with in MPLS(Multiprotocol Label Switching) or IP for theirs backbone network.
(vi) Mobility still supported at layer2, and hence like 2G it still prohibits seamless roaming beyond heterogeneous access networks and routing domains.
(vii) The transmission were band frequencies are between 1900 and 2200 MHz. All UMTS license holders at the UK holds a 20-year license with the condition that 80% population coverage is achieved by 31 December 2007.
(viii) The present third generation licensed operators in the UK can be seen below as at August 2004.

(i)  The second generation of mobile systems was placed on digital transmission with GSM.
(ii) GSM stands for (Global System for Mobile communication) was most popular standard which is used in second generation, using 900MHl and 1800MHz for the frequency bands.
(iii) GSM mobile systems grown digital transmission using SIM. SIM stands for (Subscriber Identity Module) technology to authenticate a user for identification and bllling purposes and to encrypt the data to prevent listen without permission (eaves dropping).
(iv)  The transmission used as TDMA. TMDA stands for (Time Division Multiple Access) and CDMA One stands for (Code Division MultipleAccess ) method to increase the amount of information transported on the network.
(v) Mobility is supported at layer 2, which stops seamless roaming across assorted access networks and routing domains. This means each operator must cover the entire area or have agreements in place to permit roaming.