dear sirs
what is the main difference between the 4G-LTE and the 5G -LTE , and how we can implement the LTE concept in the 5G new radio?
4G is the branding name for LTE, while 5G is the branding name for NR. Hence, I would say that there is no such thing as implementing 4G/LTE in 5G/NR.
However, the 5G standard builds heavily on 4G standard, to the extent that it can sometimes be deployed as a software upgrade of a 4G base station and where a 4G core network can be used. But it is not backward compatible in the sense that a 4G device cannot connect to a 5G base station.
Emil Björnson thanks a lot for your kindly answer.. I have the subject (Performance enhancement of massive Mimo LTE for 5G wireless communication) is this subject is matched with the current standard for 4G and 5 G? .. I think word LTE in the subject is incorrect
Karrar, LTE is a modulation standard. It is the only modulation used in 4G cellular, and it is also used in 5G cellular for the lower frequency bands. For example, in the US anyway, when 5G is transmitted in the UHF band, it uses LTE.
Looks like LTE will be used in 5G cellular, along with the newer modulation types. And it also looks like 4G and 5G will coexist for quite some time, where 5G phones can use either system.
One good reason being, in the US, 5G cannot be located close to airports!
4G technology (LTE) is based on a time frame structure where every frame has 1-ms and the channel access has to be at the beginning of every 1-ms frame. On the other hand, in Wi-Fi technology, there is no time frame structure where every Wi-Fi node can start the transmission after sensing the channel to be idle for a certain time period by following its own channel access mechanism. As a result, while coexisting LTE with Wi-Fi in unlicensed band, LTE cannot start transmission until the beginning of its next 1-ms frame. For example, if the channel is free, LTE should wait until the beginning of the next frame and a reservation signal method is followed by transmitting a dummy signal that has no information to keep the channel busy and to prevent other Wi-Fi nodes from accessing the channel. This channel access mechanism followed by LTE would waste the spectrum in the case where the transmission of LTE is ready to start at any point other than the beginning of a frame. On the other hand, in 5G NR-U, this synchronization problem is solved by using flexible numerology where a dynamic adjustment for the number of sub-carriers and the duration of mini-slots is possible. In particular, the channel access scheduling in LAA of 5G NR-U can decrease the slot duration from 1-ms down to 125 µs. This means that the dummy signal transmission is not needed to reserve the channel and this would be achieved by following the gap based access mechanism which allows the contention process to start at the right time. Therefore, if the channel is free, the transmission process can start in the next frame without any need to waste time of the remaining 1-ms by a dummy signal as in LTE-LAA. It can be noticed that the spectrum is used more efficiently for LAA in 5G NR-U compared to LTE and this is the main difference. Karrar Haider Al Taai
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