Monday, 30 March 2015

Straight Cable and Cross-over Cable

Common Ethernet network cables are straight and crossover cable. This Ethernet network cable is made of 4 pair high performance cable that consists twisted pair conductors that used for data transmission. Both end of cable is called RJ45 connector.
The cable can be categorized as Cat 5, Cat 5e, Cat 6 UTP cable. Cat 5 UTP cable can support 10/100 Mbps Ethernet network, whereas Cat 5e and Cat 6 UTP cable can support Ethernet network running at 10/100/1000 Mbps. You might heard about Cat 3 UTP cable, it's not popular anymore since it can only support 10 Mbps Ethernet network.Straight and crossover cable can be Cat3, Cat 5, Cat 5e or Cat 6 UTP cable, the only difference is each type will have different wire arrangement in the cable for serving different purposes.
Straight CableYou usually use straight cable to connect different type of devices. This type of cable will be used most of the time and can be used to:

1) Connect a computer to a switch/hub's normal port. 

2) Connect a computer to a cable/DSL modem's LAN port.  

3) Connect a router's WAN port to a cable/DSL modem's LAN port.  

4) Connect a router's LAN port to a switch/hub's uplink port. (normally used for expanding network)  

5) Connect 2 switches/hubs with one of the switch/hub using an uplink port and the other one using normal port.

 In straight cable connectivity is like as followsRJ451 Connected to RJ452                               

Pin1------------------------------------- Pin1    

Pin2------------------------------------- Pin2 

Pin3------------------------------------- Pin3 

Pin4------------------------------------- Pin4 

Pin5------------------------------------- Pin5  

Pin6------------------------------------- Pin6  

Pin7------------------------------------- Pin7 

Pin8------------------------------------- Pin8 

Crossover Cable Sometimes you will use crossover cable, it's usually used to connect same type of devices. A crossover cable can be used to:

1) Connect 2 computers directly.  

2) Connect a router's LAN port to a switch/hub's normal port. (normally used for expanding network) 

3) Connect 2 switches/hubs by using normal port in both switches/hubs.

 RJ451 Connected to RJ452  

Pin1------------------------------------- Pin3

Pin2------------------------------------- Pin6

Pin3------------------------------------- Pin1

Pin4------------------------------------- Pin4

Pin5------------------------------------- Pin5

Pin6------------------------------------- Pin2

Pin7------------------------------------- Pin7

Pin8------------------------------------- Pin8




 

2G Wireless System

2g network concerns with the second generation wireless telecommunication technology. The 2g technology uses digital radio signals, while its predecessor, 1G, was based on analog radio signals.
What the market needs today is the 2g wireless technology, capable of servicing complex commercial relationships and second generation of b-to-b ecommerce systems all across the world. For the future of e-commerce, strategic buying and selling where the action is, there is a growing need to develop dynamic commercial relationships. 2g technologies focus just on that – to unleash the potential of the Internet to transform commercial relationships. 2G mobile technologies allows much greater access enabling different mobile phone networks to offer services like text messages, picture messages and MMS.

About 2G Technology Capacity
The recent technological developments have made it possible for operators to get more value out of 2G technology. The last five years have seen a lot of technological innovations taking place in 2G technology, thus improving the 2g technology capacity. The prime focus of this page is to shed light on the capacity in 2g technologies and the recent developments in this area.
Some of the latest innovations have resulted in delivery of a higher 2g technology system capacity, thus improving on its efficiency and working. Many technological developments have been initiated to increase the capacity of 2g technology, widening the bandwidth of the networks. This also enables the operators to offer new services in these platforms.
The 2g technology capacity between the handsets and the towers can be increased in two ways, by using digital signals.
First, through the use of various codecs the digital voice data can be condensed and multiplexed much more successfully than analog voice encodings. This improves the 2g technology capacity and allows more calls to be packed into the same amount of radio bandwidth.
The second way to increase the capacity of 2g technology is to focus on the cells. As the digital systems are designed to emit less radio power from the handsets, it means that the cells could be smaller. Smaller cells mean that more cells could be placed in the same amount of space. This also made the related equipment to get less expensive.

What Is 2G Technology?

2g technologies are based on what type of multiplexing is employed, for instance, the procedure of merging multiple digital data streams into one signal. Classified by whether they are based on time division multiple access (TDMA) or code division multiple access (CDMA), the 2G standards may include the following: Integrated Digital Enhanced Network (IDEN) or Global System for Mobile communications (GSM), used worldwide. Digital Advanced Mobile Phone System (D-AMPS) is used in North and South America, while Personal Digital Cellular (PDC) is used in Japan.
2G telecom networks were commercially launched in 1991 on the GSM standard in Finland. The 2G systems were found to be considerably more efficient on the spectrum, allowing far greater mobile phone penetration levels. Moreover, the phone conversations were digitally encrypted.
Getting on with the meaning of 2g technology, 2G makes use of a CODEC or compression-decompression algorithm for compressing and to multiplex digital voice data. Using this technology, it is possible for a 2G network to bundle more calls per amount of bandwidth. As the data is transmitted through digital signals, 2G also offers extra services such as SMS and e-mail. Moreover the battery lasts longer due to the lower-powered radio signals. Digital voice encoding, offering a feature of error checking, also improves the sound quality by reducing dynamic and lowering the noise floor.
Although 2g technologies have much more benefits to offer over its predecessors, it has a few disadvantages as well. The 2G's digital signals are very dependent on location and proximity. A call made from far away may not allow the digital signal to be strong enough to reach it. Moreover, the digital signals used in 2g technologies have a jagged, angular curve, which can fail completely under unsuitable conditions.

How 2G Technology Works?

The 2G technology or Second generation technology was launched in Finland in 1991.In this article, we will focus on the working of 2g technologies and the technology of 2g. The technology behind 2g is based on GSM or in other words global system for communication.
Depending on the type of multiplexing used, the 2G technologies are divided into TDMA-based (time division multiple access) and CDMA-based standards (code division multiple access). While the TDMA allows for the division of signal into time slots, the CDMA on the other hand allocates each user a special code to communicate over a multiplex physical channel. TDMA assigns each call a certain portion of time on a designated frequency and the CDMA gives a unique code to each call, thus spreading it over the available frequencies. The last part of each name, which is multiple access, simply means that more than one user can make use of each cell.
The main standards for technology behind 2g are:
GSM 
TDMA-based, although it originated in Europe, this is used in almost all countries on all the main continents. Accounting for more than 80% of all subscribers around the world, CDMA2000 in the 450 MHz frequency is used by over 60 GSM operators.
IS-95 aka cdmaOne
CDMA-based, this technology of 2g is used in parts of America and Asia. Used by about 17% of all subscribers globally, one sees many CDMA operators migrating to GSM in countries like Mexico, India, Australia and South Korea.
PDC
TDMA-based, this is used exclusively in Japan
iDEN
TDMA-based, this proprietary network is in use by Nextel in the United States and Telus Mobility in Canada.
IS-136 aka D-AMPS
TDMA-based, it was once widespread in the America but today most operators have migrated to GSM.
The working of 2g technologies in GSM helped it to first establish international roaming. This facilitated all the mobile subscribers to use their mobile phone connections in many different countries across the world. Unlike 1G technology, GSM technology is based on digital signals. This technology behind 2g is advantageous to both the network operators and the users at the same time.

Disadvantages Of 2G Technologies

Although the 2G technology is widespread and popular in use, there do exist some disadvantages of 2g technologies, which you may not be familiar with. The reason is that these drawbacks of 2g technology are often not well publicized.
Here are the main disadvantages of 2g technologies:
Weaker digital signal
Some areas which are less populated, if the digital signals are weak, they will not be sufficient enough to reach a cell tower. This particular problem is more often on 2G systems positioned on higher frequencies. For 2G systems deployed on lower frequencies, this is not a problem. Regulations about where 2G can be deployed may vary from country to country. However, this is looked upon as one of the main disadvantage of 2g technology.
Angular decay curve
One of the other disadvantages of 2g technologies is due to the fact that the digital signal has jagged decay curve, unlike the Analog, which has a smooth decay curve. Under unfavorable conditions, digital will have occasional dropouts, and may fail completely if the conditions worsen.
Reduced range of sound
The digital calls, although are free of static and background noise, the use of lossy compression by the codec’s takes a toll and the range of sound that they transmit is reduced. You may hear less of the tonality of someone's voice conversing on a digital cellphone, which is one of the drawbacks of 2g technology.
Some of the other disadvantages of 2g technologies are that the pulse nature of TDMA transmission used here often interferes with some electronics, like certain audio amplifiers. Moreover, as the intellectual property is concerted among a few industry members, it creates obstacles for new entrants. This in turn limits the competition among phone manufacturers. Another disadvantage of 2g technology is that GSM has a fixed maximum cell site range of 35 km, which is imposed by technical limitations.


Friday, 27 March 2015

1G Wireless System

The First generation of wireless telecommunication technology is known as 1G was introduced in 1980. The main difference between then existing systems and 1G was invent of cellular technology and hence it is also known as First generation of analog cellular telephone. In 1G or First generation of wireless telecommunication technology the network contains  many cells (Land area was divided into small sectors, each sector is known as cell, a cell is covered by a radio network with one transceiver) and so same frequency can be reused many times which results in great spectrum usage and thus increased the system capacity i.e. large number of users could be accommodated easily.
Use of cellular system in 1G or First generation of wireless telecommunication technology resulted in great spectrum usage.  The First generation of wireless telecommunication technology used analog transmission techniques which were basically used for transmitting voice signals. 1G or  first generation of wireless telecommunication technology also consist of various standards among which most popular were Advance Mobile Phone Service (AMPS), Nordic Mobile Telephone (NMT), Total Access Communication System (TACS). All of the standards in 1G use frequency modulation techniques for voice signals and all the handover decisions were taken at the Base Stations (BS). The spectrum within cell was divided into number of channels and every call is allotted a dedicated pair of channels. Data transmission between the wire part of connection and PSTN (Packet Switched Telephone Network) was done using packet-switched network.
Different standards of 1G were used worldwide like:
In 1982 Advance Mobile Phone Service (AMPS) was employed in United States and later it was used in Canada, Central America, South America, Australia,  Argentina, Brazil, Burma, Brunei, Bangladesh, China ,Cambodia, Georgia, Hong Kong, Indonesia, Malaysia, Kazakhstan, Mexico, Mongolia, Nauru, New Zealand, Pakistan, Guinea, Philippines, Russia, Singapore, South Korea, Sri lanka, Tajikistan, Taiwan, Thailand, Vietnam, Western Samoa.
Total Access Communication System (TACS) / Extended Total Access Communication System (ETACS) was employed in United Kingdom, United Arab Emirates, Kuwait, Macao, Bahrain, Malta, Singapore.
Nordic Mobile Telephone-450 (NMT-450) was employed in Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Hungary, Poland, Russia, Spain, Sweden, Thailand, turkey and Ukraine.
Nordic Mobile Telephone-900 (NMT-900) was employed in Cyprus, Denmark, Finland, France, Greenland, Netherlands, Norway, Switzerland and Thailand.
C-NETZ (C-NETZ in German refers to C Network which was the first cellular wireless telephone network in Germany) was employed in Germany, Portugal and South Africa.
Radiocom2000 was employed in France.
Radio Telephone Mobile System (RTMS) was employed in Italy
Nippon Telephone and Telegraph (NTT) was first employed in Japan and later NTACS (Narrowband Total Access Communications System) and JTACS (Japanese Total Access Communication System) were also employed.
Use of Analog signals for data (in this case voice) transmission led to many problems those are:
1. Analog Signals does not allow advance encryption methods hence there is no security of data i.e. anybody could listen to the conversion easily by simple techniques. The user identification number could be stolen easily and which could be used to make any call and the user whose identification number was stolen had to pay the call charges.
2. Analog signals can easily be affected by interference and the call quality decreases.
3. Poor Voice quality
4. Poor Battery Life
5. Large phone size
6. No Security
7. Limited Capacity - It allows voice call in one country.
8. Poor Handoff Reliability
9. It's speed was up to 2.4 kbps

History of WiMax

The idea for what is now known as WiMax began in the mid 1990's. At that time, the technology industry was seeing tremendous growth and new, exciting ideas were being found everywhere. It was clear to telecommunications service providers that there was a huge desire for broadband Internet access. This desire was coming from both home users and corporate users. Many telecommunications companies began planning and designing distribution networks that would be capable of handling the high traffic volumes expected. In most cases, their answer was fibre optic cables.The need to use fibre optic cables to provide widespread broadband Internet access came at a huge cost. Some estimates put this cost at about $300 per foot of fibre. As you can imagine this type of network would get very expensive very quickly. As this was being done, some industry players were busy looking for an alternative which could provide the widespread broadband Internet access without costing an arm and a leg. Their solution was to use a wireless technology.In the early days of this wireless broadband access, and still today actually, its biggest cheerleader was Intel. Intel was in the midst of a prolonged slump in sales and saw an opportunity in this type of wireless access, and for good reason. Up until this point Intel had been a key player, a very successful player I might add, in the emerging WiFi market. Intel had been involved with WiFi since the beginning and even integrated WiFi capability into their popular Centrino line of processors. Since Intel had the expertise and the experience in WiFi wireless access they were hoping that they could leverage that into success in another type of wireless access.
Of course, Intel had some challenges. Firstly, in North America many service providers were already implementing fibre optic networks for the delivery of broadband Internet access so many business leaders felt that the market for wireless broadband Internet access may be limited to developing markets. Secondly, some service providers had already begun experimenting with their own wireless broadband solutions.
In these early days there was a real patchwork of technologies which didn't adhere to any agreed upon standard. Without an agreed upon industry standard many users were hesitant to purchase the required hardware for fear of being "locked-in" to a particular service provider. Or worse, that the technology would prove unpopular and would quickly become obsolete. This fear by consumers is perfectly rational and has been previously shown to be justified (just look at the VHS / Beta fiasco). So, with consumers hesitant to purchase the required hardware it is understandable that hardware manufacturers would be hesitant to even make the devices and risk low sale volumes. Intel recognized the problems of not having an agreed upon standard and set about to convince others. It didn't take a lot of convincing.

Wednesday, 18 March 2015

Ad-Hoc network with 2 PC's

Connect Two PC With WiFi Setup for PC-1:
1. Open 'Properties' of 'My computer'.
My computer>Properties
2. Click on 'Computer Name' Tab, and then click on 'Change' Button. Give it a name; here we are using 'PC-1'.
My computer>Properties>Computer Name
3. Also change 'Workgroup', provided at the bottom of same dialog box. Give it any name as 'Howtix'.
My computer>Properties>Computer Name>Workgroup
4. Now, goto 'Network Connections' & open 'Properties' of your 'Wireless Network adapter'
Network Connections>Wireless Network adapter>Properties
5. Goto 'Wireless Network' Tab & click on 'Advanced' button. Select Computer to Computer (Ad-Hoc) connection option. Now click on add preffered networks & specify details as:
o Network name (SSID) - WiFi 
o Network Authentication - Open
o Data Encryption - Disabled
6. Tick this connection if it’s not already done.
7. Now configure TCP/IP connection settings. Goto 'General' Tab & select 
'Internet protocol (TCP/IP) & click properties. Enter following values:
o IP Address - 192.168.0.1
o Subnet Mask - 255.255.255.0
o Default Gateway - 192.168.0.2
8. Click 'OK' &  save the changes.


Connect Two PC With WiFi Setup for PC-2:
9. Open 'Properties' of 'My computer'.
My computer>Properties
10. Click on 'Computer Name' Tab, then click on 'Change' Button. Give it a  name, here we are using 'PC-2'.
My computer>Properties>Computer Name 
11. Also change 'Workgroup', provided at the bottom of same dialog box. Give it any name as 'Howtix'.
My computer>Properties>Computer Name>Workgroup
12.  Now, goto 'Network Connections' & open 'Properties' of your 'Wireless Network adapter'
Network Connections>Wireless Network adapter>Properties
13. Goto 'Wireless Network' Tab & click on 'Advanced' button. Select Computer to Computer (Ad-Hoc) connection option. Now click on add preffered networks & specify details as:
o Network name (SSID) - WiFi 
o Network Authentication - Open
o Data Encryption - Disabled
14. Tick this connection if its not already done.
15. Now configure TCP/IP connection settings. Goto 'General' Tab & select 'Internet protocol (TCP/IP) & click properties. Enter following values:
o IP Address - 192.168.0.2
o Subnet Mask - 255.255.255.0
o Default Gateway - 192.168.0.1
16. Click 'OK' &  save the changes.
Now open your Network Adapters & connect. Note that the paths for various operating systems may vary, but process will be the same.