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. The three classes of multiple access protocols are, random access, taking-turns and channel partitioning. With random access protocol, each node tries to randomly to use the complete broadcast link, without any regard to the other nodes. Taking-turns protocol uses some type of turning mechanism, which designates which node is allowed to transmit. Channel partitioning protocol divides the channel (time slots, frequency, code) and assigns them evenly between all the nodes in the
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TDM divides time into time frames and further divides each time frame into time slots. Each time slot is then assigned to one of the nodes. Whenever a node has a packet to send, it transmits the packet’s during its assigned time slot in the revolving TDM frame. (Kurose 448) Advantage of TDM is no collisions and each node gets dedicate transmission rate during each time frame. A disadvantage is nodes must always wait for its turn in the transmission sequence even if it is the only device with a frame to transmit. FDM divides the channel into different frequencies and assigns each frequency to a node. FDM thus creates smaller channels of out of the single, larger channel. FDM shares both the advantages and disadvantages of TDM. While TDM and FDM assign time slots and frequencies, to the nodes, CDMA assigns a different code to each node. Each node, then uses its unique code to encode the data bits it sends. In CDMA networks different nodes can transmit simultaneously and their respective receivers correctly receive a sender’s encoded data in spite of interfering transmissions by other nodes. (Kurose 449) CDMA was first used during World War II by English allies to stop German attempts at jamming transmissions by transmitting over several frequencies, making it difficult for the Germans to pick up the complete signal. The company Qualcomm created communication chips for CDMA technology, and were the first to commercialize it. CDMA is widely used in cellular networks. CDMA main competitor cellular networks is GSM (Global System for Mobile communication). CDMAis prevalent in most parts of North America, while GSM is widespread in Western Europe and other parts of the world. CDMA has several advantages, encrypted communication channels, simultaneously transmit numerous conversations. Disadvantages are
TDM divides time into time frames and further divides each time frame into time slots. Each time slot is then assigned to one of the nodes. Whenever a node has a packet to send, it transmits the packet’s during its assigned time slot in the revolving TDM frame. (Kurose 448) Advantage of TDM is no collisions and each node gets dedicate transmission rate during each time frame. A disadvantage is nodes must always wait for its turn in the transmission sequence even if it is the only device with a frame to transmit. FDM divides the channel into different frequencies and assigns each frequency to a node. FDM thus creates smaller channels of out of the single, larger channel. FDM shares both the advantages and disadvantages of TDM. While TDM and FDM assign time slots and frequencies, to the nodes, CDMA assigns a different code to each node. Each node, then uses its unique code to encode the data bits it sends. In CDMA networks different nodes can transmit simultaneously and their respective receivers correctly receive a sender’s encoded data in spite of interfering transmissions by other nodes. (Kurose 449) CDMA was first used during World War II by English allies to stop German attempts at jamming transmissions by transmitting over several frequencies, making it difficult for the Germans to pick up the complete signal. The company Qualcomm created communication chips for CDMA technology, and were the first to commercialize it. CDMA is widely used in cellular networks. CDMA main competitor cellular networks is GSM (Global System for Mobile communication). CDMAis prevalent in most parts of North America, while GSM is widespread in Western Europe and other parts of the world. CDMA has several advantages, encrypted communication channels, simultaneously transmit numerous conversations. Disadvantages are