Multiplexing

Multiplexing CHAPTER 4 Outline * Frequency Division Multiplexing(FDM) * Synchronous Time Division Multiplexing * Statistical Time Division Multiplexing * Asymmetric Digital Subscriber Line(ADSL) Multiplexing * Set of techniques that allows the simultaneous transmission of multiple signals across a single link * allows several transmission sources to share a larger transmission capacity Link = physical path Channel = portion of a link that carries a transmission

Orthogonal Frequency Division Multiplexing or OFDM is a modulation format that is being used for many of the latest wireless and telecommunications standards. OFDM has been adopted in the Wi-Fi arena where the standards like 802.11a, 802.11n, 802.11ac and more. It has also been chosen for the cellular telecommunications standard LTE / LTE-A, and in addition to this it has been adopted by other standards such as WiMAX and many more. Orthogonal frequency division multiplexing has also been adopted for

Abstract multiple carriers are simultaneously modulated using Orthogonal frequency-division multiplexing (OFDM) which is a transmission technique. Since the OFDM-based system has high spectral efficiency and is robust against intersymbol interference and frequency-selective fading channels. The major problem of this system is high peak-to-average power ratio (PAPR) of transmitted signal which causes distortion of signal. At the Receiver, to reduce PAPR in removing weight with no distortion PAPR

The one with the Minimum Mean Square Error (MMSE) among Ortogonal Frequancy Division Multiplexing candidate signals is selected for transmission. From the results, it can be seen that a proposed scheme based iterative partial transmit sequence can be easily implemented with low combining complexity, still maintaining a better BER performance and peak to average power ratio reduction, compared to the conventional partial transmit sequence approach. In mobile communication environment due to fading

communicate. Multiplexing: transmitting multiple information in a single medium has been made easier by the process called multiplexing. Using this technique the total bandwidth is divided and a portion is given to each signal. Multiplexer and demultiplexer are the devices used in multiplexing. The multiplexer combines the data from multiple source and sends via the single channel and demultiplexer separates the individual lines and transmits to corresponding output lines. Multiplexing is of four types

major techniques that allocate capacity for wireless WAN communications. These techniques are Time Division Multiple Access (TDMA), Frequency Division Multiple Access (FDMA), Code Division Multiple Access (CDMA), and Orthogonal Frequency Division Multiplexing (OFDM). (Goleniewski, L. 2007) Each technique has pros and cons when compared amongst each other. The following is a summary of why each technique has a need, and some of the challenges that come with that technique. Radio Frequency Radio Frequency

Downlink Multiplexing The multiplexing chain in the downlink is largely comparable to that in the uplink however there are also certain functions that are done in a different way. As like in the uplink, the interleaving is executed in two components, covering both intra-frame and inter-frame interleaving. In addition, the rate matching permits one to stabilise the necessary channel symbol energy for various service qualities. The services can be mapped to more than one code additionally, which is

the maintaining cost. Two key technologies are used in passive optical network: the first one known as TDM-PON uses Time Division Multiplexing to multiplex traffic from/to multiple ONUs onto the upstream/downstream wavelength. It requires complex scheduling algorithms and framing technology to support a variety of services. The second is Wavelength division multiplexing passive optical network “WDM PON”. This technology comes to extend the

as before. 1.2.2 Second Generation Optical Networks These networks were made capable of using multiple carrier wavelengths that were multiplexed onto a single fiber thus offering increased bandwidth. The technique is called wavelength division multiplexing. From technological point of view, incorporating the switching and routing functionality in the optical domain and allowing for the transparency of data format, protocol and bit rates are the achievements of second generation over

In data communication, they are always striving to increase throughput, this would include allowing nodes to transmit information over a single broadcast link without interfering with each other. To achieve this, multiple access protocols coordinate the transmission. There are three classes of multiple access protocols, random access, taking-turns and channel partitioning. With random access protocol, each node tries to randomly to access the complete broadcast link, without any regard to the other