Question 1
i. Spread spectrum includes resistance to natural interference, such as noise, jamming, and it also limits power flux density. For wireless communication the spread spectrum technology results in a much greater bandwidth than the signal would have if its signals were not varied.
ii. Spreading uses noise like signals called wideband that are hard to detect or intercept. Spreading is achieved by using two Methods: Direct Sequence Spread Spectrum (DSSS) which refers to a technique whereby the system performs an (XOR) on the user bit stream called a chipping sequence. Many chips results in a higher bandwidth. Frequency Hopping Spread Spectrum (FHSS) is a system whereby the transmitter changes carrier frequency according to a certain hopping pattern. The frequency changes are ultimately determined by a pseudo random number sequence. FHSS comes into two variants called slow hopping and fast hopping.…show more content… Medium Access Control algorithm refers to all the mechanisms that regulate access to the medium such as SDM, TDMA, FDM, or CDM, ALOHA etc. Some of the well known MAC algorithms and Protocols are ALOHA and CSMA. ALOHA wireless MACs define rules for orderly access to a shared medium, which includes fairness and efficient sharing of bandwidth. These protocols avoid packet collisions at the receiver due to interference. Carrier Sense Multiple Access (CSMA) is an algorithm based on the concept of sensing if a channel is free before data transmission. Sensing refers to monitoring the status of the channel to determine whether it is free or busy. If the channel is free/idle the data can be transmitted and if the channel is busy the sending station needs to keep sensing until the channel becomes idle. ALOHA protocols share channel bandwidth in a more brute force manner. ALOHA allows a node that has data to transmit to do so immediately. Collisions are common in such a system. Feedback mechanism such as Automatic Repeat request (ARQ) is needed to ensure packet
