ted into multi- ple fragments. In this case, a fragment number is assigned to each segment. When a packet is segmented into multiple MAC frames, those fragmented frames are assigned the same sequence number and different values for the fragment number. IEEE 802.11 can transmit a maximum of 2304 bytes of higher layer data. 8.1.4 LTE and NR Solutions for Operation in Unlicensed Spectrum The traditional methods of interworking between cellular networks and Wi-Fi have proved to be cumbersome, with practical limitations in handling the mobility of the IP flows 866 Chapter 8 Backoff following delayed transmission Source Destination Contention window Others NAV (RTS) NAV (CTS) Defer Access Source Frag 0 Frag 1 Frag 2 Destination Others NAV (RTS) NAV (Frag 0) NAV (Frag 1) NAV (CTS) NAV (ACK0) NAV (ACK 1) Defer Access Figure 8.9 Medium access and contention control in IEEE 802.11 [30]. between cellular and Wi-Fi networks. All these schemes have suffered from complexity to define which Wi-Fi networks can be selected for traffic offload, and in which condition a Wi-Fi network should be selected SO that it provides the best performance. For these needs, 3GPP has specified access network discovery and selection function (ANDSF), where an ANDSF server in the operator network controls the connection manager at the device. The ANDSF may have location-dependent network selection policies, defining how and in which priority order to select Wi-Fi networks. It is noted that the UE local operating envi- ronment and user preferences are important. The ANDSF has recently included comparative signal and load thresholds to instruct the UE when it should use the cellular base station and when to use the selected Wi-Fi access points for any given flow. Due to the lack of commercial interest in ANDSF, 3GPP has decided to integrate Wi-Fi into cellular networks by RAN-level features, which can provide scalability as a Wi-Fi access node acts in a simi- lar manner as an eNB does, rather in the packet data network. A Wi-Fi access point may be in