“…Paper Year Network type Cross-layers parameters Observations [16] 2012 CR network physical layer: power allocation, AMC this design demonstrated effective improvement in TCP throughput, as well as increase in average network lifetime MAC layer: frame size functionalities transport layer: best relay selection [17] 2016 CRAHNs physical layer: spectrum sensing this improved design eliminated the frequent slow start and mostly had a large TCP congestion window which enhanced overall the transmission efficiency MAC layer: channel switching transport layer: TCP-improved algorithm [18] 2010 CR networks physical layer: spectrum sensing, modulation and coding, access decision low-layer design parameters can significantly impact on the TCP throughput over CR networks, which were improved through cross-layer approach in their work MAC layer: frame size transport layer: TCP [19] 2013 IEEE 802.22 WRAN based CR networks physical layer: spectrum sensing proposed solutions perform close interaction between the transport and MAC/PHY layers to enhance TCP performance MAC layer: scheduling transport layer: TCP [20] 2015 CR network MAC layer: resource allocation demonstrated higher traffic load and lower delay for CR network network layer: routing [21] 2015 CRAHNs MAC layer: scheduling and random channel access high utilisation of unused spectrum by SU and throughput maximisation among coexisting peer nodes network layer: routing [22] 2017 CRAHNs MAC layer: TDMA scheduling collision among SUs is avoided by incorporating distributed TDMA MAC and location aware forwarding protocol network layer: channel selection [23] 2012 CRAHSN physical + MAC layer: modulation, channel coding, propagation, power transmission, channel estimation, hole detection, horizontal handover, hardware temperature monitoring reduced energy consumption by CR nodes and optimisation of spectrum resources network + transport layer: standards recognition, vertical handover, inter/ intra network handover, link load analysis application layer: user profile attribute control (sound, video, speed, indoor/outdoor, operator etc.) [43] 2018 CRAHNs physical layer: power control achieved optimal transmit power and optimal data rate for upstream SUs transport layer: congestion control, rate control [44] 2018 underlay CRN physical layer: dynamic spectrum access, SINR achieved improved video quality and efficient load balancing of transmitted packets network layer: routing, queue management, resource allocation IET Commun., 2020, Vol. 14 Iss.…”