channel design. 2.2 Coherent Optical OFDM The application of OFDM to optical communications used surprisingly late and relatively compared with RF complement, although the first paper on optical OFDM in the open literature was created by Pan and Green in 1996 and also in this year’s some research was happen. However, the fundamental advantages of OFDM against optical channel dispersion was not recognized in optical communication until 2001, when OFDM to combat model model dispersion in multimode
frequency-division multiplexing(OFDM) waveform and attains a maximum data rate of around 54 Mbps. It was one of the most widely used protocols for wireless systems. However, 802.11g operated at 2.4 GHz band and used the same OFDM waveform as that of 802.11a. It was revised in 2003 and came into public use with a maximum possible bit rate of about 54 Mbps. IEEE 802.11n wireless protocol was not just a revision but some revol... ... middle of paper ... ... 802.11n standard like MIMO, OFDM, channel bonding and
G in 1G, 2G, 3G and 4G stands for the “Generation” of the mobile network. Today, mobile operators have started offering 4G services a higher number before the ‘G’ means more power to send out and receive more information and therefore the ability to achieve a higher efficiency through the wireless network. During the time of 1G, radio signals were transmitted in ‘Analogue’ form. 2G networks on the other hand, were based on narrow band digital networks. The 3rd generation of mobile networks has become
such as closed subscriber group, self-organising networks, location services, enhancement cell ID and Multimedia Broadcast services this is a standard which pretty much became the norm. Technologies such as Orthogonal Frequency Division Multiplexing (OFDM) and Multiple-Input Multiple-Output(MIMO) which were instrumental in the evolution to the LTE-Advanced are also discussed. scalable multiple transmission bandwidths are supported by LTE including one for the packet-switching (PS) mode. Whereby, all
which are ways of combining multiple signals. The four main techniques include: frequency division multiple access (FDMA), time division multiple access (TDMA), code division multiple access (CDMA), and orthogonal frequency division multiplexing (OFDM). FDMA was used in 1G mobile systems (and still used in combination with other techniques today) and assigned one subchannel to each frequency. TDMA was invented in the second generation of mobile phones when the technology switched from analog to
6. Practical Applications of PM and FM 1. Radio Transmitting Radio is device that use technology of using radio waves to transfer information, such as sound, by using the properties of electromagnetic energy waves transmitted through space, such as their phase, amplitude, frequency, or pulse width. If radio waves passing an electrical conductor, the oscillating fields induce an alternating current in the conductor. The information in the waves can be get back into its original form. Radio
Data Center: Data center, in the context of big data, is not only for data storage but it plays significant role to acquire, manage and organize the big data. Big data has uncompromising requirement for storage and processing capacity. Hence the data center development should be the focus for effective and rapid processing capacity. With the increasing scale of data centers, the operational cost should be reduced for the development of data centers. Today’s data centers are application-centric, powering
Dense wavelength division multiplexing (DWDM) is a technology that puts data from different sources together on an optical fiber, with each signal carried at the same time on its own separate light wavelength. Using DWDM, up to 80 (and theoretically more) separate wavelengths or channels of data can be multiplexed into a light stream transmitted on a single optical fiber. Each channel carries a time division multiplexed (TDM) signal. In a system with each channel carrying 2.5 Gbps (billion bits per
Getting in touch with anyone anywhere in the world is not a problem anymore. We can contact anyone on the move anytime. The basic concept of cellular phone was developed in the 1940s. Mobile phones were the beginning of the wireless communication. They are the used extensively now days. From year to year the number of mobile phones subscribers increases. According to the data in the International Institute of Communications (IIC), World Bank, Britain ranked second position of having the largest mobile
1. Introduction • Wi-Fi also common spell with Wifi or interCap word WiFi, is one of the most popular wireless communication standards on the market that exchange data or internet by wirelessly using radio waves. Wi-Fi is technically a trademarked brand name for the wireless standard owned by the Wi-Fi Alliance, much like Bluetooth® is trademarked by the Bluetooth Special Interest Group. The Wi-Fi Alliance also defines Wi-Fi as any WLAN product that based on the IEEE 802.11 standard. However, only
Figure 6: WiMAX vs WIFI coverage Figure 6 shows the WiMAX and WiFi coverage. Once can clearly see how large is the coverage of WiMAX. Wi-Fi and WiMAX are corresponding. WiMAX networks usually provides a WiMAX subscriber unit which links to the metropolitan WiMAX network gives Wi-Fi located in homes or business for local devises for example Laptops, Wi-Fi Handsets and iPhones for connections (Xiao, 2008). This makes the users to put the WiMAX Subscriber Unit in the areas, which it can be received
a. What does the network layer do? What is interior routing and what is exterior routing? In the Open Systems interconnection Model (OSI Model), the network layer lies in the third level and for network communication it provides paths for data routing. It is considered as the backbone of the OSI model because for the purpose for the data transfer between nodes, network layer performs selection and management of the best logical path. Switches, firewalls, bridges and routers are some hardware devices
crowding problem by introducing the opportunistic usage of frequency bands. Which are not heavily occupied by licensed users since they cannot be utilizing by the users other than the licensed owner at moment. Orthogonal Frequency Division Multiplexing (OFDM) is one of the widely used technologies in wireless communication systems which have the potential of fulfilling the requirements of cognitive radios inherently or with minor changes. 1.2 Basic of Cognitive Radio (CR) Cognitive radio (CR) concept
Analog and Digital Technologies To understand the technologies of analog and digital conversions we must first understand what analog and digital transmissions are. Analog transmissions are a continuous variable in amplitude and frequency. The frequency band that they operate over defines analog circuits. People generally produce a bandwidth of 9,900Hz with frequencies in the range of 100Hz to 10,000Hz. Speech that falls between 250Hz and 3,400Hz is considered intelligible speech and therefore the