The further integration of telecommunications and industry has been consider⁃able and is expected to bring significant benefits to society and economics in 6G.It also forms some evolution trends for next-generation communication systems,including further rises in machine-type communications(MTC),uplink-dominated systems,and decentral⁃ized structures.However,the existing access protocols are not friendly to these trends.This paper analyzes the problems of existing access protocols and provides novel access technologies to solve them.These technologies include contention-based non-orthogonal multiple access(NOMA),data features,enhanced pilot design and successive interference cancellation(SIC)of diversity.With these key enablers,truly grant-free access can be re⁃alized,and some potential modifications of protocols are then analyzed.Finally,this paper uses massive and critical scenarios in digital transformations to show the great necessity of introducing novel access technologies into future communication protocols.
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