Tuesday, January 19, 2010

4G Wireless Systems

Fourth generation wireless system is a packet switched wireless system with wide area coverage and high throughput. It is designed to be cost effective and to provide high spectral efficiency . The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB),and Millimeter wireless. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.The high performance is achieved by the use of long term channel prediction, in both time and frequency, scheduling among users and smart antennas combined with adaptive modulation and power control. Frequency band is 2-8 GHz. it gives the ability for world wide roaming to access cell anywhere.

Wireless mobile communications systems are uniquely identified by "generation designations. Introduced in the early 1980s, first generation (1G) systems were marked by analog frequency modulation and used primarily for voice communications. Second generation (2G) wireless communications systems, which made their appearance in the late 1980s, were also used mainly for voice transmission and reception The wireless system in widespread use today goes by the name of 2.5G-an "in between " service that serves as a stepping stone to 3G. Whereby 2G communications is generally associated with Global System for Mobile (GSM) service, 2.5G is usually identified as being "fueled " by General Packet Radio Services (GPRS) along with GSM. In 3G systems, making their appearance in late 2002 and in 2003, are designed for voice and paging services, as well as interactive media use such as teleconferencing, Internet access, and other services. The problem with 3G wireless systems is bandwidth-these systems provide only WAN coverage ranging from 144 kbps (for vehicle mobility applications) to 2 Mbps (for indoor static applications). Segue to 4G, the "next dimension " of wireless communication. The 4g wireless uses Orthogonal Frequency Division Multiplexing (OFDM), Ultra Wide Radio Band (UWB), and Millimeter wireless and smart antenna. Data rate of 20mbps is employed. Mobile speed will be up to 200km/hr.Frequency band is 2 ]8 GHz. it gives the ability for world wide roaming to access cell anywhere.

Monday, January 11, 2010

Thursday, January 7, 2010

Configure TCP/IP from the Command Prompt

In order to configure TCP/IP settings such as the IP address, Subnet Mask, Default Gateway, DNS and WINS addresses and many other options you can use Netsh.exe.

Netsh.exe is a command-line scripting utility that allows you to, either locally or remotely, display or modify the network configuration of a computer that is currently running. Netsh.exe also provides a scripting feature that allows you to run a group of commands in batch mode against a specified computer. Netsh.exe can also save a configuration script in a text file for archival purposes or to help you configure other servers.

Netsh.exe is available on Windows 2000, Windows XP and Windows Server 2003.

You can use the Netsh.exe tool to perform the following tasks:

  • Configure interfaces
  • Configure routing protocols
  • Configure filters
  • Configure routes
  • Configure remote access behavior for Windows-based remote access routers that are running the Routing and Remote Access Server (RRAS) Service
  • Display the configuration of a currently running router on any computer
  • Use the scripting feature to run a collection of commands in batch mode against a specified router.

What can we do with Netsh.exe?

With Netsh.exe you can easily view your TCP/IP settings. Type the following command in a Command Prompt window (CMD.EXE):

netsh interface ip show config

With Netsh.exe, you can easily configure your computer's IP address and other TCP/IP related settings. For example:

The following command configures the interface named Local Area Connection with the static IP address 192.168.0.100, the subnet mask of 255.255.255.0, and a default gateway of 192.168.0.1:

netsh interface ip set address name="Local Area Connection"

static 192.168.0.100 255.255.255.0 192.168.0.1 1

(The above line is one long line, copy paste it as one line)

Netsh.exe can be also useful in certain scenarios such as when you have a portable computer that needs to be relocated between 2 or more office locations, while still maintaining a specific and static IP address configuration. With Netsh.exe, you can easily save and restore the appropriate network configuration.

First, connect your portable computer to location #1, and then manually configure the required settings (such as the IP address, Subnet Mask, Default Gateway, DNS and WINS addresses).

Now, you need to export your current IP settings to a text file. Use the following command:

netsh -c interface dump > c:'location1.txt

When you reach location #2, do the same thing, only keep the new settings to a different file:

netsh -c interface dump > c:'location2.txt

You can go on with any other location you may need, but we'll keep it simple and only use 2 examples.

Now, whenever you need to quickly import your IP settings and change them between location #1 and location #2, just enter the following command in a Command Prompt window (CMD.EXE):

netsh -f c:'location1.txt

or

netsh -f c:'location2.txt

and so on.

You can also use the global EXEC switch instead of -F:

netsh exec c:'location2.txt

Netsh.exe can also be used to configure your NIC to automatically obtain an IP address from a DHCP server:

netsh interface ip set address

"Local Area Connection" dhcp

Would you like to configure DNS and WINS addresses from the Command Prompt? You can. See this example for DNS:

netsh interface ip set dns "Local Area Connection" static 192.168.0.200

and this one for WINS:

netsh interface ip set wins "Local Area Connection"

static 192.168.0.200

Or, if you want, you can configure your NIC to dynamically obtain it's DNS settings:

netsh interface ip set dns"Local Area Connection" dhcp

BTW, if you want to set a primary and secondary DNS address, add index=1 and index=2 respectively to the lines of Netsh command.

As you now see, Netsh.exe has many features you might find useful, and that goes beyond saying even without looking into the other valuable options that exist in the command.


Wednesday, January 6, 2010

Change Ip Address Of Ur Computer

1. Click on "Start" in the bottom left hand corner of screen
2. Click on "Run"
3. Type in "command" and hit ok

You should now be at an MSDOS prompt screen.

4. Type "ipconfig /release" just like that, and hit "enter"
5. Type "exit" and leave the prompt
6. Right-click on "Network Places" or "My Network Places" on your desktop.
7. Click on "properties"

You should now be on a screen with something titled "Local Area Connection", or something close to that, and, if you have a network hooked up, all of your other networks.

8. Right click on "Local Area Connection" and click "properties"
9. Double-click on the "Internet Protocol (TCP/IP)" from the list under the "General" tab
10. Click on "Use the following IP address" under the "General" tab
11. Create an IP address (It doesn't matter what it is. I just type 1 and 2 until i fill the area up).
12. Press "Tab" and it should automatically fill in the "Subnet Mask" section with default numbers.
13. Hit the "Ok" button here
14. Hit the "Ok" button again

You should now be back to the "Local Area Connection" screen.[/B]
15. Right-click back on "Local Area Connection" and go to properties again.
16. Go back to the "TCP/IP" settings
17. This time, select "Obtain an IP address automatically"
18. Hit "Ok"
19. Hit "Ok" again
20. You now have a new IP address