[With the 4G telecommunications systems now starting to be deployed,people are looking towards the development of 5th generation or 5G technology services.Although the deployment of any wireless or cellular system take years,development of the 5G technology systems is being investigated.The new 5G technologies will need to be chosen developed and perfected to enable timely and reliable deployment. The new 5th generation,5G technology for cellular systems will probably start to come to fruition around 2020.

The current status of the 5G technology for cellular systems is very much in the early development stages.Many companies are looking into the technologies that could be used to become part of the system.In addition to this,a number of universities have set up 5G research units focused on developing the technologies for 5G. In addition, the standards bodies,particularly 3GPP are aware of the development but are not actively planing the 5G systems yet.Many of the technologies to be used for 5G will start to appear in the systems used for 4G and then as the new 5G cellular system starts to formulate in a more concrete manner,they will be incorporated into the new 5G cellular system.

The major issue with 5G technology is that there is such an enormously wide variation in the requirements:super fast downloads to small data requirements for IoT than any one system will not be able to meet these needs.Accordingly a layer approach is likely to be adopted.As one commentator stated:5G is not just a mobile technology.It is ubiquitous access to high & low data rate services.]

Based on the paragraph above,at present,5G technology for cellular systems（  ）, many of the technologies to be used for 5G（  ）in the systems used for 4G,the major issue facing with 5G technology is（  ）.