Wireless IP, The Killer Application !?

My website and thesis captures the essential elements in the convergence path of wireless networks and Internet protocols resulting in the new paradigm of "Wireless IP." It covers all the important 1G/2G cellular technologies that I have seen in the past decade, along with 3G and 4G, Wireless Local Area Network (WLAN) technologies,including modifications required in protocols, architectures, and framework in virtually every area such as QoS, security, mobility, and so on.

The thesis can be useful for anyone who is interested in the convergence of the wireless and IP networks and for them who need to understand how packet data services and IP work in the wireless world. Furthermore, the thesis represents my views and opinions , based on my technical understanding and experience in these areas

Because the increase of higher system capacities and data rates provided by latest and proposed wireless network technologies, and their closer integration with the Internet enabled by the IP technologies used in these wireless networks are enabling many new ways for people to communicate.
Also people on moving vehicles (e.g. cars, trains, boats and airplanes) may access the Internet or their enterprise networks the same way as when they are at their offices or homes. They may be able to surf the Internet, access their corporate networks, download games from the network, play games with remote users, obtain tour guidance information, obtain real-time traffic and route conditions information.

Wireless networks are evolving into wireless IP networks to overcome the limitations of traditional circuit-switched wireless networks. Wireless IP networks are more suitable for supporting the rapidly growing mobile data and multimedia applications.
IP technologies (such as Mobile IP) are the most promising solutions available today for supporting data and multimedia applications over wireless networks. IP-based wireless networks will bring the globally successful Internet service into wireless networks. The mobile or wireless Internet will be an extension to the current Internet.

Advanced mobile data and multimedia applications such as; MMS, play games in real time with remote users, Voice over wireless (VoIP calls) and broadcasting of audio and video advertisements to mobile phone users such as: advertiser supported phone calls, Wireless IP-enabled radio and watch TV, will grow very fast. New IP broadcasting techniques such as DVB-H (Digital Video Broadcasting for Handhelds), will make it possible to bring video broadcasting services to handheld receivers.

In particular, the growth of advanced mobile data and multimedia applications such as Voice-over-IP (VoIP) help increase multimedia traffic over the wireless networks significantly. Thus, Wireless IP can also be a killer sometimes. Therefore future Wireless IP networks can only be able to service those mobile data and multimedia applications without congestions in the Wireless network, if those Wireless IP networks are ready for it. In other words, "those networks need to be controlled (e.g. by QoS parameters or other specific protocols) end must have enough bandwidth to support all this types of services. Wireless networks and the IP technologies within those networks have to be reviewed and evolved constantly.

Remark these words:
The traffic on broadband wireless networks will be increasingly IP

Archive for Thesis


Radio Link Efficiency

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A radio interface is bandwidth constrained because it is bound to use limited spectrum. Although 3G networks claim to provide bit rates up to 2 Mbps, it is still a far cry from the 52.8 Mbps a Very high Data rate Digital Subscriber Line (VDSL) can offer on a single twisted-pair copper loop. Similarly, bit rate of 11 Mbps in WLAN is no comparison to 1 Gbps of the gigabit Ethernet (IEEE 802.3). Therefore, it is highly desired to use the available bandwidth as efficiently as possible, so as to give the user a decent performance for IP compared to the wired world. Cellular operators pay a significant amount of their deployment costs in acquiring a spectrum. Therefore, radio link efficiency is also highly desired for cost savings.

One approach to improving efficiency for some IP protocols is to use header compression. A problem with IP is namely its large header overhead.

Bandwidth efficiency can also be improved by performing compression on IP payloads. Sometimes IP payloads are already compressed (images, audio, video, “zipped” files) by the applications or are already encrypted above the IP layer. For payload compression the best bandwidth efficiency can be achieved if application-level compression techniques are used extensively. The challenge is to ensure that almost all the applications have a compression mechanism and are using them over wireless links.


IP-level dormancy and paging

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Wireless IP networks can be similarly divided into several paging areas. The paging area information can be broadcast with the help of specific radio broadcast capabilities. The mobile node can remain idle within the paging area without needing to perform idle mobility procedures, thus saving power. The mobile node can switch to dormant mode by registering itself as a dormant node to a network element that handles dormancy and paging functions. It needs to wake up only when it crosses the paging area to update its new paging location.

Any downstream traffic toward the mobile node triggers a paging request to wake up the mobile node within that paging area.

The benefit of IP-level dormancy and paging is twofold. It offers these power-saving functions to wireless access technologies like WLAN that do not have such capabilities at the layer 2 level.

Although all cellular technologies do provide these functions, implementing IP-level dormancy offers transparency between the layer 2 functions and the layer 3 functions. Another incentive to IP-level dormancy and paging is due to its access network independence, as discussed in the previous section. Paging when combined with mobility management protocols can provide a very desirable solution for dormancy of mobile hosts in IP networks.

Some current wireless networks, 3G, and future cellular networks are capable of providing high rates over radio connections. Thus, they will have communication bandwidth capabilities similar to the fixed hosts and therefore will be capable of using voice over IP and digital audio and video streaming.

3G cellular networks have already defined QoS classes as part of the radio link layer, but these definitions are limited from the mobile node over the cellular radio up to some core network element that terminates these QoS levels. These networks employ native technology for QoS resource management and admission control to admit or reject any QoS requests from users based on subscription profile and available resources. Additionally, interworking between the QoS classes defined in terms of end-to-end service levels must be mapped to QoS classes over the radio.


The QoS Challenge

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The challenge of QoS is not introduced by wireless networks alone, but it was realized with the introduction of new high-bandwidth applications on the Internet. Normal IP data services, referred to as background or best-effort services, like email, Web browsing, FTP, and telnet sessions can work fine without a need for QoS. As new applications like voice over IP, multimedia streaming, and other bandwidth-hungry applications come into existence, the need to manage, control, differentiate, and guarantee the desired service levels has become an important issue. The user perception of quality is determined by end-to-end factors like latency, jitter, throughput, bit-error rate, and bandwidth.

The details of the mobility mechanisms in each of the cellular networks at the radio level and roaming across different networks are dependent on the protocols used for that specific cellular technology. Users can roam only to the networks that support the same cellular technology.

For example, GSM users can roam only to similar GSM networks. When other non-cellular access technologies (e.g., WLAN) are considered, it is even worse since currently there is no common network infrastructure and protocol exchange to support roaming between these access networks.


Idle Mobility

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Cellular networks are operated by different service providers, and each service provider manages the network by dividing the network into manageable network areas in a hierarchical fashion, all the way down to the cell level. Mobile nodes are identified by location based on which cell the user is presently in.

Cellular networks perform location management by continuously tracking the location of mobile nodes with the help information received from the mobile nodes. The location information determines the cell (or a larger network area) where the mobile node is currently located. The location information is broadcast to all the mobile nodes in the network or cell area.


The Mobility Challenge

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Mobility is an important feature in cellular networks and in any wireless network. Hence, it has been a key design element and an integrated part of current cellular network architectures. However, this is not the case with IP networks, and hence mobility can be considered as one of the biggest challenges for IP.

Without support for mobility, the applicability of IP to cellular networks is quite limited and may result in wireless-specific solutions to handle mobility.


The Radio Link Challenge

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Although IP and its application protocols are designed as link generic to accommodate a very wide range of data link networks, there was an implicit assumption in the designs that the network is a wired network.

Now that the wireless is adopting these protocols, it is realized that the radio links have their own characteristics, which impact the performance of the IP protocols.

These impacts are more significant in the case of Wireless Wide Area Networks (e.g. cellular networks) and Wireless Personal Area Network (e.g. Bluetooth), compared to the Wireless LAN (IEEE 802.11).

This is because WWAN and WPAN offer more latency and limited bandwidth. Thus the limitations of IP applicability to wireless networks are also based on the characteristics of radio links for IP.

What this points out is that :
• There is the Non-Line-Of-Sight (NLOS),WiFi sort of service, where a small antenna on your computer connects to the tower. In this mode, WiMAX uses a lower frequency range, 2 GHz to 11 GHz (similar to WiFi). Lower-wavelength transmissions are not as easily disrupted by physical obstructions — they are better able to diffract, or bend, around obstacles.

• There is Line-Of-Sight (LOS) service, where a fixed dish antenna points straight at the WiMAX tower from a rooftop or pole. The line-of-sight connection is stronger and more stable, so it’s able to send a lot of data with fewer errors. Line-of-sight transmissions use higher frequencies, with ranges reaching a possible 66 GHz. At higher frequencies, there is less interference and lots more bandwidth.


What can WiMAX do?

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WiMAX operates on the same general principles as WiFi, it sends data from one computer to another via radio signals. A computer (either a desktop or a laptop) equipped with WiMAX would receive data from the WiMAX transmitting station, probably using encrypted data keys to prevent unauthorized users from stealing access.

WiMAX should be able to handle up to 70 megabits per second. Even once that 70 megabits is split up between several dozen businesses or a few hundred home users, it will provide at least the equivalent of cable-modem transfer rates to each user. WiMAX outdistances WiFi by miles.
WiMAX will blanket a radius of 30 miles (~50 km) with wireless access. The increased range is due to the frequencies used and the power of the transmitter. Of course, at that distance, terrain, weather and large buildings will act to reduce the maximum range in some circumstances, but the potential is there to cover huge tracts of land.