4G Networks—Adoption and Dangers

4G is short for fourth-generation cellular communication system. There is no set definition for the specifics of 4G. The 4G will be a fully IP-based integrated system of systems and network of networks, achieved after the convergence of wired and wireless networks as well as computer, consumer electronics, communication technology, and several other convergences. These will be capable of providing 100 Mbps and 1Gbps, respectively, in outdoor and indoor environments with end-to-end QoS and high security, offering any kind of services anytime, anywhere, at affordable cost and one billing. The Wireless World Research Forum (WWRF) defines 4G as a network that operates on Internet technology, combines it with other applications and technologies such as Wi-Fi and WiMAX, and runs at speeds ranging from 100 Mbps (in cell-phone networks) to 1 Gbps (in local Wi-Fi networks). 4G is not just one defined technology or standard, but rather a collection of technologies and protocols to enable the highest throughput and lowest cost wireless network possible

Fourth generation networks are likely to use a combination of WiMAX and WiFi. Technologies employed by 4G may include SDR (Software-Defined Radio) receivers, OFDM (Orthogonal Frequency Division Multiplexing). OFDMA (Orthogonal Frequency Division Multiple Access). MIMO (multiple input/multiple output) technologies, UMTS (Universal Mobile Telecommunications Service) and TD-SCDMA (Time Division Synchronous Code Division Multiple Access). All of these delivery methods are typified by high rates of data transmission and packet-switched transmission protocols. 3G technologies, by contrast, are a mix of packet and circuit-switched networks. When fully implemented, 4G is expected to enable pervasive computing in which simultaneous connections to multiple high-speed networks provide seamless handoffs throughout a geographical area. Network operators may employ technologies such as cognitive radio and wireless mesh networks to ensure connectivity and efficiently distribute both network traffic and spectrum

Moreover, the objective to 4G is to offer seamless multimedia services to users accessing an all IP-based infrastructure through heterogeneous access technologies. IP is assumed to act as an adhesive for providing global connectivity and mobility among networks. 4G will more resemble a conglomerate of the existing technologies rather than an entirely new standard. An all IP-based 4G wireless network has inherent advantages over its predecessors. It is compatible with, and independent of the actual radio access technology. With IP, one basically gets rid of the lock-in between the core networking protocol and the radio protocol. IP tolerates a variety of radio protocols. It lets one design a core network that gives complete flexibility in the access network type.

The goal of this chapter is to study development, transition, and challenges in 4G implementation and mobility management issues. Mobility management has been recognized as one of the most important and challenges problems for a seamless access to wireless network and mobile service. It is the fundamental technology used to automatically support mobile terminals and join their services while simultaneously roaming freely without the disruption of communication. Mobility management operations are introduced, along with the discussions of key research issues and possible solutions.

Consequences for Handover Strategies

The auditory results help to answer the research questions raised at the beginning of this section:

1. The most important network characteristic is the packet loss rate. The second most important characteristic is the audio bandwidth. Switching the audio bandwidth is roughly equivalent to the quality degradation of 5-10% packet loss, in both narrowband and wideband conditions. The degradations due to network handover (make-before-break) alone - without codec switching - are negligible in comparison to packet loss and bandwidth switching.
2. Switching codecs is advantageous if the packet loss rate is high, and if the changeover helps to reduce the packet loss impact. Switching codecs in order to take profit of a larger audio bandwidth is advantageous only if a sufficiently long period of WB speech transmission remains. From the limited results of our tests, it seems that this minimal length is around 30 seconds. Unfortunately, it is not possible to know the remaining length of a call. As a workaround, handover strategies could consider the perceived quality and use this value to estimate multiple scenarios (using different remaining lengths), and then select the most beneficial for the user, assuming past and current conditions. An interaction could be observed between packet-loss and audio-bandwidth degradations:
   • If packet loss is high (low basic quality), the impact of audio bandwidth on perceived quality is low.
   • If packet loss is low (high basic quality), the impact of audio bandwidth on overall call quality is high.
3. Parametric quality prediction models like the E-model are not yet able to estimate the speech quality resulting from codec changeovers. Signal-based models like WB-PESQ do a better job, but do not always perform as well on in-scope data.

The results may help to design efficient network handover and codec changeover strategies. In bad network conditions (high packet loss rate), a handover should be made if the packet loss rate can be reduced by this step. In this situation, it is not important whether the audio bandwidth can be maintained or not; the reduction of packet loss should be the ultimate goal. In contrast to this, a handover can also be fruitful in good network conditions (low packet loss rate). In this case, switching to a higher audio bandwidth can help to significantly improve quality. The improvement is most effective if it occurs early in the call; the remaining call duration should be more than 30 seconds. Changing from WB to NB is always linked to a loss in quality; the pure network handover without codec changeover, however, does not significantly impact the perceived quality.