Editing Medium access control (section)

== Cellular networks ==
[[Cellular network]]s, such as [[GSM]], [[UMTS]] or [[LTE (telecommunication)|LTE]] networks, also use a MAC layer. The MAC protocol in cellular networks is designed to maximize the utilization of the expensive licensed spectrum.<ref name=Miao>{{cite book|author1=Guowang Miao|author2=Jens Zander|author3=Ki Won Sung|author4=Ben Slimane|title=Fundamentals of Mobile Data Networks|publisher=[[Cambridge University Press]]|isbn=978-1107143210|year=2016|author1-link=Guowang Miao}}</ref> The [[air interface]] of a cellular network is at layers 1 and 2 of the OSI model; at layer 2, it is divided into multiple protocol layers. In UMTS and LTE, those protocols are the [[Packet Data Convergence Protocol]] (PDCP), the [[Radio Link Control]] (RLC) protocol, and the MAC protocol. The base station has absolute control over the air interface and schedules the downlink access as well as the uplink access of all devices. The MAC protocol is specified by [[3GPP]] in TS 25.321<ref>[http://www.3gpp.org/ftp/Specs/html-info/25321.htm  3GPP TS 25.321 Medium Access Control (MAC) protocol specification]</ref> for UMTS, TS 36.321<ref>[http://www.3gpp.org/ftp/Specs/html-info/36321.htm  3GPP TS 36.321 Evolved Universal Terrestrial Radio Access (E-UTRA); Medium Access Control (MAC) protocol specification]</ref> for LTE and TS 38.321<ref>[http://www.3gpp.org/ftp/Specs/html-info/38321.htm  3GPP TS 38.321 NR; Medium Access Control (MAC) protocol specification]</ref> for [[5G]].