Instead of directly diving into 5G first we should know how communications occurs and from what technology 5G has evolved. So lets dive into basics , how multiplexing allows multi users to access to network. What is multiplexing ? It is basically when a lot ot of users data is passed through a common channel and when multiple users connect with a network using common channel is called a multiple access. For example multiple users can be connected to same Wifi and the wifi will provide each user a frequency band within its range to transfer or receive data ,in form of packets. Now there are some techniques using which a network differentiate its users , first is FDMA(Frequency division multiple access) ,in this lets say to a station multiple users are connected ,then the radio waves frequency would be different for each connected user and there will be guard bands to prevent interference of information.
Second is TDMA(Time Division Multiplexing Access) in which multiple users transfer data along a single common frequency band by allocating different time slots. We can say each user is given N seconds of the time slots .Now this technology is used in 2G ,GPRS and GSM . But in this ,the channel only support 8 slots that is only 8 users can be connected at once .Though using dynamic allocation, channel was increased but still each channel can only support 8 users at a time.
Then came the CDMA , in this the signals were spread across a large frequency band .In this our data is mixed with some pseudo code or we can say our data bits are modulated by high orthogonal frequency bits .Now the data from the other user is also modulated by a pseudo random code ,thus spreading over large frequency band . At last they both are transmitted through a same frequency band. This technology is called as 3G, basically W-cdma which spreads signal in more bandwidth .
Now the question is why we are not satisfied with the existing techniques ? whats the need to evolve? Its i because he number of users are increasing by day ,so need to evolve from 1G,2G,3G to 4g and radio part from GSM to HSPA+ as gsm has low data bandwidth (25khz). Also need to improve our modulation techniques and spectral efficiency , we moved from QPSK TO 64QAm.
From CDMA we move on to OFDMA for high data rates and spectral efficiency.Which is our 4G , now as the name suggests. OFDMA (Orthogonal frequency division multiplexing) uses orthogonal sub carriers equally spaced at 15khz and each user is provide subset of these carries for data transmission and unlike previous techniques there are no time slots or frequency slots , user is allocated available bandwidth according to the resource availibility. Also there are no guard bands , the sub carriers overlaps with each other in the same frequency domain but are arranged in orthogonal way that they never interferes.Then there is LTE which is a kind of 4G that provides fastest connection to mobile Internet experience ten times faster than 3G.
Now with the strong internet services and million of users we move form world of LTE Advanced to the next Generation communication system which is 5th Generation. Features have been planned to be added in the 5th Generation are firstly : Pervasive networks :,where a user can concurrently be connected to several wireless access technologies and seamlessly move between them. Secondly ,Group cooperative relay, a technique that is being considered to make the high data rates available over a wider area of the cell. Third is the Cognitive radio technology that would enable the user equipment or handset to look at the radio landscape in which it is located and choose the optimum radio access network, modulation scheme and other parameters to configure itself to gain the best connection and optimum performance. Lastly Smart antennas which is ans another major element of any 5G cellular system . Using these it will be possible to alter the beam direction to enable more direct communications and limit interference and increase overall cell capacity.
Shristi uniyal 