Challenges for Future 4G Networks

We have established that 4G convergence is expected to deal with several environments, including short range networks, which, in general, involve devices with capabilities subject to CPU, memory and disk limitations. Thus, with regard to routing, the next generation network should consider strategies that conserve battery power not only from a device survival point of view but more importantly in an attempt to use greener environment friendly solutions. These are also known as power-aware routing. For example, these devices should avoid the use of highly demanding table updates.

Routing mechanisms using location information have been proposed in order to improve energy consumption and data delivery. Note that the excessive use of location information from devices such as GPS for routing decisions can lead to a considerable increase in energy consumption when compared to location agnostic solutions. Moreover, vehicular networks are also expected to maintain location servers for vehicles to help in information routing.

In existing 2G and 3G networks, there is the horizontal cell connectivity handoff, one that involves cell changes by a terminal within the same type of network. 4G introduces also the vertical handoff. Here devices are expected to change networks they attach to. Hence, the challenge is to design routing protocols that are capable of handling vertical handoffs between pairs of different types of networks, while maintaining QoS requirements and optimizing common radio resources availability.

Under 4G networks, security is also seen as a paramount concern. Traditional attacks on existing IP networks will certainly migrate to 4G networks encouraged by both the heterogeneity and the open air interfaces of such networks. Routing information may be targeted in such attacks on system security, there is a need to design secure routing approaches to ensure the integrity of routing in 4G systems. This is not however the object of this chapter.

In summary, among the many routing-related challenges this work has identified, we mentioned QoS, security, energy and location information. The following section will present the details of new routing algorithms, with new network metrics and routing mechanisms, which motivate the extension of traditional classification to include epidemic, biological and social class of routing ideas, one expects to see in 4G networks.

CHALLENGES TO 4G VISION

Simplicity and security are the main challenges for the consumers of wireless devices. All consumers have different needs but they all want simplicity i.e. use of their wireless device at any place any time. Corporate houses also want to ensure that their employees are accessing confidential data in a secure way. 4G technology will require massive innovation and substantial investment. It requires multiple changes in technology and network infrastructure, in handsets and software. A huge amount of innovation is necessary to deliver this kind of promise. As discussed the 4G network will be fully Internet protocol (IP) wireless infrastructure and thus this will give the ability to exploit the capabilities of Internet. The major challenges in realizing the 4G visions are:

1. Power consumption: Multiple processing and communication elements will increase the current drain. Managing power use in the infrastructure will play a vital role in achieving 4G technology. Additional hardware acceleration technology is required to manage power. OFDM based technology is crucial to manage some of the process streams and power challenges in such kinds of applications and devices. Some form of management of current drain and reduced battery drain is required for better battery life.
2. Spectrum efficiency: More spectrum is required to be made available. For this we have to refurbish existing spectrum. Use of cognitive radio can improve the spectral efficiency. Even with these steps, the 4G radio access network will need to provide significantly better spectral efficiency.
3. Cost: This is not only about infrastructure, operating or handset costs but also the cost of deployed services too. To deliver the spectral efficiency, the coverage is required. And for coverage there will be a dramatic growth in the number of base stations. Three times more base stations will be required to deliver a ten fold increase in data rate. Deployment of advanced antenna techniques such as MIMO and Space-Time Coding (STC) can improve spectrum efficiency, as well as reduction in growth rate of base stations; thus the capital cost will be reduced. On the handset side, there are significant challenges in continuing to drive down the cost of integrating greater and greater processing capability in multi mode RF technology.
4. Miniaturization and Processing Challenges: Miniaturization challenges include power reduction, cost, size and product development cycle. Multimode technology in 4G means availability of different types of radio access technologies in a seamless way. There are significant software, billing, carrier interoperability and enterprise carrier interoperability challenges. For bulk CMOS (Complementary Metal Oxide Semiconductor) process technologies, various companies are trying to provide higher performance at lower power as the semiconductor industry migrates from 90nm to 65nm to 45nm to 32nm technology. It is expected that in next five to ten years the evolving bulk CMOS technologies will completely resolved these complications. RF CMOS are continuing to scale for high-speed high-resolution A/D converters, and isolation techniques are being developed in the industry for multiple radio operation and single-chip die integration.
5. Advanced Architectures for 4G: In WCDMA, there are two variables -coding and time. With OFDM-based 4G, frequency, space and time are being used as variables to extract the data. With OFDM, information is separated into small sub-bands, and the information in each of these bands can be signal-processed independently in a parallel fashion. As consumers expect continuous service, so parallel processing is being increased so that the net result is that a high-speed, low-power drain OFDM engine architecture which can be developed to support 4G data throughput requirements. OFDM is typically discussed as being a WiMAX technology. WiMAX is an important technology as base business model behind broadband wireless access.
6. Business Challenges: 4G is not going to be driven by a single entity or organisation. It will require a tremendous number of partnerships and a robust ecosystem which can exploit the capabilities that are available in wireless technologies. Multiple standards bodies, corporations and government entities are required to come together to drive standards-based interoperability and the opportunity to deliver 4G networks. Governments will have to manage the spectrum in different parts of the world, and this will have a dramatic impact on how we can exploit the capabilities available to us in wireless technologies. To enable triple-play merged services delivered over wired and wireless networks, the issue of equipment has also to be taken into account for affordability, simplicity, interoperability and reliability.
7. Miscellaneous challenges: As we move from circuit-switched networks to IP networks, some of the challenges include packet acceleration, traffic management, data integrity, security and quality of service, which all represent different challenges for us on the infrastructure side compared to the traditional network infrastructure. This notion of high performance in a very constrained power envelope continues to be a significant challenge open standards continue to be another issue.
8. Challenges in IP Network Security and Traffic Control: Wireline internet access is increasingly being challenged to improve security. Security has multiple elements, much more than just moving encrypted traffic at faster and faster rates across the network. Security is also about denial of service attacks and digital rights management. These are all becoming carrier problems. Improved security and quality of service require providers to be able to identify video packets and prioritize them so that viewers get an uninterrupted stream of video content, if they are watching a movie or TV show on demand. These security / quality of service capabilities are the key elements of managing the network in both wireless and wireline infrastructure. From the processor perspective, the network processor has been exceptionally efficient at driving performance at layers 2 and 3, but suffers a significant drop-off in performance in layer 4-7 protocols. A general-purpose microprocessor does not deliver the kind of performance networks require at layer 2, and does little better at layers 4-7. Today's communications processors use hardware acceleration techniques to achieve better performance in the lower levels and do slightly better in the higher levels. But there is still a significant content processing gap in terms of microprocessor, network processor and communications processor technologies. Clearly one of the requirements is the ability to provide a solution that does not just forward headers and IP packets. We need to inspect those packets; connect those packets and carry out stream processing instead of packet processing. In terms of base station size and cost constraints, there is a trend towards more base stations covering smaller areas while managing multiple power output limits, frequencies and standards.
9. Financial Challenges: There are various financial challenges in reducing the cost of power amplifier in the base station which manifests as a largest expense. Other financial challenges are cost of components, software or services providers or carriers; significant investment is required to enable the next generation 4G network

EPC Challenges | LTE AND IPV6

The EPC changes key networking paradigms for previous mobile generations (2G/3G) core networks and the integration of EPC is expected to address a number of technological challenges successfully.

The radio side in LTE (eNodeB) has undergone significant technological advances to provide wider spectral bands and efficient use of the spectrum, which are reserved for LTE, which results greater performance and system capacity. At the same pace, the mobile core is required to change and to provide higher throughput while maintaining low latency; both due to the improved and simplified flat all-IP network architecture.

The important aspect of LTE is the introduction of new technologies and the delivery of the high performance LTE solution, which are both involved on the radio side.

The EPC needs to address the following key aspects of IP for the LTE deployment:

1. Distributed versus centralized network architectures, including; SGW, PGW, and MME deployment.
2. Network addressing and IP routing, and realtime management for large IP domains.
3. The introduction, strategy, and coordination of IPv6 and its interoperability with IPv4.
4. End-to-end deployment for QoS and underlying transport coordination.
5. Data and control plane end-to-end security.
6. Layer 2 versus Layer 3 transport layer connectivity (eNodeB, PGW, SGW, MME).
7. External networks and VPNs interconnectivity.
8. Lawful Interception and Deep Packet Inspection (DPI).

There is a set of stringent requirements for scalability, reliability, and high-performance elements because of LTE's dynamic nature of user mobility, which are coupled with the large-scale deployment targets and short duration of multiple data sessions for each UE.

To satisfy these requirements, the EPC elements must have the best classification with high IP performance. In order to address all these fundamental aspects of EPC's and according to the network element and product level, a new generation of scalable mobile core equipment, purpose-built, and strong IP expertise are required.

It is important to integrate all these elements together to deliver the needed carrier-grade features for LTE. The EPC elements must fully interwork harmoniously while in both control and user planes, the fairly complex network procedures involve all EPC elements. The EPC is expected to address the demanding requirements for dynamic and multi-dimensional mobility management, policies and data bearers. This should be done in an orchestrated manner to enable the highest LTE performance, while offering interoperability and interworking with the legacy 3G/2G systems.