lite links), bearing in mind that the equator is around 40 000 km long and its half-length gives a delay of 20 000 km/3 X 108 ms-Superscript(1) = 67 ms, while the full length of the equator requires 2 X 67 ms = 134 ms. Therefore, the require- ment for end-to-end delay for voice below 150 ms (specified in ITU-T recommendation G.114) can be satisfied in CS mobile (and fixed) networks. However, PS networking principles result in increased total delay and delay variation due to packetization, cod- ing/decoding, buffering at networks nodes (switches, routers), etc. Therefore mobile network architectures have also evolved to accommodate specific characteristics of IP transfer end-to-end, which is always higher than in CS networks for the same distance (in CS networks the path is established before any call/session by using signaling, such as SS7) [2]. 5.1.1 3G Network Architecture Initially, the 3GPP mobile IP network architectures were introduced in GPRS, with two main gateway nodes, the central node SGSN (serving general packet radio service sup- port node) and the network edge node GGSN (gateway general packet radio service support node). The same two nodes defined the main core network (CN) architectures in UMTS, which was 3GPP's 3G standard (note that there were different 3G standards in the 2000s, such as cdma2000 in Americas, Mobile WiMAX 1.0, and several others [3]). The bitrates of UMTS increased in both downlink and uplink, with better modulation and coding schemes in later 3GPP releases during the 2000s, which resulted in stan- dardization of HSPA (high speed packet access), also noted globally as 3.5G. 5 QoS for Mobile Ultra-Broadband The 3GPP mobile network evolution started during the 3G era, which transformed the hierarchical mobile architecture (with a radio network controller (RNC) between the base stations, i.e. eNodeBs, and SGSN) into a flat architecture, with UTRAN (Uni- versal Mobile Telecommunication System Radio Access Network) which consisted only of NodeBs (base stations in UMTS) and centralize