What is 4G? Abbreviation of fourth generation wireless technology It will provide a comprehensive IP solution wherevoice , data and multimedia can be given to user on an“anytime , anywhere” basis. It includes several types of broadband wirelesscommunication system access including cellular telephone system.
Why 4G is required? Due to substantial growth in overall number of subscribers. Due to massive demand of new services like data , audio , image or video .
Features of 4G TECHNOLOGY Support for multimedia services like teleconferencing and wireless internet. Wider bandwidths and higher bitrates. Entirely packet-switched network. Global mobility and service portability. Support for previous wireless technologies. High internet speed. Tight network security.
Technology used in 4G OFDM UWB Smart antennas IPv6
OFDM(orthogonal frequency division multiplexing) IT transmits large amounts of digital data over a radio wave. OFDM works by splitting the radio signal into multiple smaller sub- signals that are then transmitted simultaneously at different frequencies to the receiver . By inserting a cyclic prefix between adjacent OFDM signal inter signal interference is virtually eliminated if the max. channel delay spread is less than the time interval of cyclic prefix. In OFDM the subcarrier pulse used for transmission is rectangular. Here modulation can performed by an IDFT ,which can be generated very efficiently as an IFFT . so, receiver only needs a FFT to reverse this process.
UWB(ultra wide band) .An advanced technology that can be used in 4G technology. It is typically detected as noise. It can use any part of the frequency spectrum, which means that it can use frequencies that are currently in use by other radio frequency devices . It uses a frequency of 3.1 to 10.6 Hz. It uses less power , since it transmits pulse instead of continuous signal. Special antennas are needed to tune and aim the signal.
IPv6 . IPv6 means Internet Protocol Version 6 . The Internet Protocol (IP) is the method or protocol which data is sent from one computer to another on the internet. Each computer (known as a host) on the Internet has at least one IP that uniquely identifies it from all other computers on the Internet. It includes128 bits, which is 4 times more than 32bits IP address in IPv4. Understanding of IPv6 in 4G- - 32 bits IP address looks like this 188.8.131.52 - all 4 sets are defined in different functions and usages. - the first set of the IP address (184.108.40.206) can be defined to be the“home address” purpose.
IPv6 continue…… The second set of the IP address (220.127.116.11) can be declared as the “care-of address” After these addresses from cell and PC established a link, care-of address will work instead of home address; it means that communication channel will switch from the first set to to the second set of the IPv6 address. The third set of the IP address (18.104.22.168) can be signed as mobile IP address. It is the communication channel to wire-line network and wireless network. An agent between the cell phones and PC will use this mobile IP address to establish a channel to cell phones. The last set of IP address (192.168.5.120) can be local network address for virtual private network (VPN) sharing purpose.
QOS(quality of service) In wireless networks, Quality of Service (QOS) refers to the measure of the performance for a system reflecting its transmission quality and service availability. 4G is expected to have at least a reliability of 99.99%). In 4G QOS may be divided in following ways- Transaction-level QOS describes both the time it takes to complete a transaction and the packet loss rate. Circuit-level QOS includes call blocking for new as well as existing calls . User-level QoS depends on user mobility and application type .
Software defined ratio(SDR) A software defined radio is one that can be configured to any radio or frequency standard through the use of software. The phone should automatically switch from operating on a CDMA frequency to a TDMA frequency whenever it is required. Roaming can be an issue with different standards, but with a software defined radio, users can just download the interface upon entering new territory, or the software could just download automatically.
Application In traffic control. Multimedia – video services Telemedicine. Crisis Management Virtual Navigation
Limitations Interoperability between the signaling techniques that are planned for use in 4G. Cost is another factor that could hamper the progress of 4G technology.The equipment required to implement the next- generation network are still very expensive. A Key challenge facing deployment of 4G technologies is how to make the network architectures compatible with each other. This was one of the unmet goals of 3G. As regards the operating area, rural areas and many buildings in metropolitan areas are not being served well by existing wireless networks.