Mobile World Congress MWC 2009 WIMA Forum for NFC Near Field Communications

Moving to a Unified Wireless Switch Topology Mike Powell, Senior Product Line Manager at Broadcom investigates the advantages of using a single or unified topology for all wireless services. Wireless access is quickly becoming an essential function of the enterprise network. With the arrival of 802.11n and its capacity of hundreds of megabits per access point, the value of wireless access has increased dramatically and the wireless domain is now able to extend to new applications beyond laptops – such as VoIP handsets, dual-mode smartphones, and desktop PCs – delivering a far more capable network with full mobility. As enterprises become more reliant on the wireless domain for delivery of mission-critical applications, network administrators will need to determine how to distribute this capacity without reducing network efficiency or straining their budgets. Initial enterprise wireless LAN (WLAN) deployments have offered, at best, modest bandwidth and poor security that has significantly hindered wireless usage in the enterprise. As a result, deployment has been limited to a small set of critical applications. In this scenario, IT professionals were using an overlaid architecture as a minimally-disruptive way to quickly graft WLANs onto their existing wired networks. With this approach, all WLAN traffic is tunneled to a centralized access controller where it is de-encapsulated and authenticated before entering the wired network. While 802.11n improves wireless performance, the overlay approach suffers from a network bottleneck due to inefficiencies, and it also treats wireless operations as a special service running over the network rather than being implemented as an essential, inherent feature. This leads to inefficiencies that prevent cost-effective scaling as the user base for wireless services increases. Network administrators contemplating the migration to 802.11n need to ask whether a new network architecture will be required to realize all the benefits enabled by wireless access. This article outlines the need for a new architecture, and reviews the characteristics and benefits of a solution based upon a new building block: the unified wireless/wireline switch. Making the Case for a Unified Wireless Switch Topology As WLAN traffic increases, a centralized approach multiplies the amount of loading on the network to the point that the functionality of the network is compromised for all the traffic it supports. The areas most affected include: Cost: Bandwidth increases in cost the closer it is to the core. Scalability: New controllers must be deployed in a linear relationship to the number of access points supported. This centralized approach cannot scale to 802.11n data rates without negatively impacting the network as a whole. Performance: Network latency and congestion packet loss increases. Security: As access points are added, security requirements become more difficult to meet cost-effectively. Resiliency: Centralized control creates a single point of failure. The pervasive, high bandwidth wireless enterprise demands a new unified wireless/wireline architecture that eliminates the bottlenecks and inefficiencies that arise from centralized control. Instead of handling wireless traffic as an exception, a unified network integrates wireless with traditional wired LAN services to provide a seamless interface between the two. Specifically, wireless data and management is moved from the core of the network to the network edge by terminating secure tunnels at the edge switches instead of at the access controllers in the core. Rather than routing wireless traffic to the core and back to the edge, backbone bandwidth is conserved by terminating traffic at the edge and routing traffic directly to its destination. In addition, security processing is moved to the edge, guaranteeing optimal performance that scales to meet user demands while maintaining network resiliency. New Enabling Technologies Required The move to a unified wireless switch topology is an expected evolutionary step for wireless, as emerging network technologies are commonly introduced in the core and moved to the edge as they mature. To enable the unified wireless switch network, several new technologies will be required. Leaders in the networking industry have already begun development of these technologies, with silicon and software for both switches and wireless access points expected to be ready well before large scale 802.11n deployments. The key enabling technologies include: Open, Hardware-based Encapsulation: Rather than continue with the proprietary encapsulation technologies used to backhaul wireless traffic today, the unified network will utilize new open standards such as the Internet Engineering Task Force’s (IETF’s) control and provisioning wireless access point (CAPWAP) specification that securely communicates between switches and access points. To realize the performance and cost benefits of 802.11n, the encapsulation/de-encapsulation and switching functions should be integrated with the switch silicon. Fragmentation and Reassembly: Encapsulation headers can increase packet size beyond Ethernet’s 1518-byte limit. In this instance, CAPWAP support for fragmentation and reassembly of packets solves the problem of buffering fragments without undue latency with an elegant two-fragment limit, therefore facilitating efficient silicon implementations. Distributed Access Point Management: With a centralized network, a single controller could manage anywhere between ten and hundreds of access points. In a unified network, each access point may be managed by a different edge switch. Therefore, switch clustering software will be required to form self-organizing, configuration-aware unified switches. Access rights and policy databases also need to be propagated and managed by each unified switch. Reaping the Benefits of the Unified Wireless Network The unified wireless network enables many capabilities beyond reducing installation and operational expenses that bring substantial value to the enterprise. Some of the benefits network administrators and users will experience include: Significantly improved scalability: Appropriate security capacity is introduced with each increase in bandwidth, for each access point deployed, supporting a more aligned, pay-as-you-grow investment outlay when compared to centralized wireless controllers. Simplified network management: Using a homogeneous topology will enable network administrators to view access points and switches from a single management point rather than a series of distinct wired and wireless devices. Substantially improved performance: Standardization enables wireless tunneling and other features to be implemented in silicon rather than software. Automated management: Features such as auto-configuration and dynamic radio management can be better managed on a per-device basis when compared to centralized implementations. Faster authentication: Moving client and policy enforcement to the edge increases responsiveness by reducing turnaround time. More efficient bandwidth utilization: Reducing the load over the network backbone will result in increased performance throughout the network. Reduced Latency: Users will also experience reduced latency, as well as increased network resiliency, as switching will occur at the edge versus backhauling all wireless traffic to the core and back to the edge again. Future for Unified Wireless LAN Topology Wireless services are becoming an every day, critical need for businesses, and as such, high bandwidth wireless access must be an integrated part of the enterprise network. With a unified wireless network, all of the performance, scalability and expense benefits of the traditional network are now available to support wireless traffic. Without this unification, backhauling and scaling limitations will prove cost-prohibitive while restricting the outstanding potential of high bandwidth enterprise WLANs. Source : Megazine Electronics Design

GSM History

Today the GSM cell or mobile phone system is the most popular in the world. GSM handsets are widely available at good prices and the networks are robust and reliable. The GSM system is also feature-rich with applications such as SMS text messaging, international roaming, SIM cards and the like. It is also being enhanced with technologies including GPRS and EDGE. To achieve this level of success has taken many years and is the result of both technical development and international cooperation. The GSM history can be seen to be a story of cooperation across Europe, and one that nobody thought would lead to the success that GSM is today. The first cell phone systems that were developed were analogue systems. Typically they used frequency-modulated carriers for the voice channels and data was carried on a separate shared control channel. When compared to the systems employed today these systems were comparatively straightforward and as a result a vast number of systems appeared. Two of the major systems that were in existence were the AMPS (Advanced Mobile Phone System) that was used in the USA and many other countries and TACS (Total Access Communications System) that was used in the UK as well as many other countries around the world. Another system that was employed, and was in fact the first system to be commercially deployed was the Nordic Mobile Telephone system (NMT). This was developed by a consortium of companies in Scandinavia and proved that international cooperation was possible. The success of these systems proved to be their downfall. The use of all the systems installed around the globe increased dramatically and the effects of the limited frequency allocations were soon noticed. To overcome these a number of actions were taken. A system known as E-TACS or Extended-TACS was introduced giving the TACS system further channels. In the USA another system known as Narrowband AMPS (NAMPS) was developed. New approaches

Neither of these approaches proved to be the long-term solution as cellular technology needed to be more efficient. With the experience gained from the NMT system, showing that it was possible to develop a system across national boundaries, and with the political situation in Europe lending itself to international cooperation it was decided to develop a new Pan-European System. Furthermore it was realized that economies of scale would bring significant benefits. This was the beginnings of the GSM system. To achieve the basic definition of a new system a meeting was held in 1982 under the auspices of the Conference of European Posts and Telegraphs (CEPT). They formed a study group called the Groupe Special Mobile ( GSM ) to study and develop a pan-European public land mobile system. Several basic criteria that the new cellular technology would have to meet were set down for the new GSM system to meet. These included: good subjective speech quality, low terminal and service cost, support for international roaming, ability to support handheld terminals, support for range of new services and facilities, spectral efficiency, and finally ISDN compatibility. With the levels of under-capacity being projected for the analogue systems, this gave a real sense of urgency to the GSM development. Although decisions about the exact nature of the cellular technology were not taken at an early stage, all parties involved had been working toward a digital system. This decision was finally made in February 1987. This gave a variety of advantages. Greater levels of spectral efficiency could be gained, and in addition to this the use of digital circuitry would allow for higher levels of integration in the circuitry. This in turn would result in cheaper handsets with more features. Nevertheless significant hurdles still needed to be overcome. For example, many of the methods for encoding the speech within a sufficiently narrow bandwidth needed to be developed, and this posed a significant risk to the project. Nevertheless the GSM system had been started. Launch dates

Work continued and a launch date for the new GSM system of 1991 was set for an initial launch of a service using the new cellular technology with limited coverage and capability to be followed by a complete roll out of the service in major European cities by 1993 and linking of the areas by 1995. Meanwhile technical development was taking place. Initial trials had shown that time division multiple access techniques offered the best performance with the technology that would be available. This approach had the support of the major manufacturing companies which would ensure that with them on board sufficient equipment both in terms of handsets, base stations and the network infrastructure for GSM would be available. Further impetus was given to the GSM project when in 1989 the responsibility was passed to the newly formed European Telecommunications Standards Institute (ETSI). Under the auspices of ETSI the specification took place. It provided functional and interface descriptions for each of the functional entities defined in the system. The aim was to provide sufficient guidance for manufacturers that equipment from different manufacturers would be interoperable, while not stopping innovation. The result of the specification work was a set of documents extending to more than 6000 pages. Nevertheless the resultant phone system provided a robust, feature-rich system. The first roaming agreement was signed between Telecom Finland and Vodafone in the UK. Thus the vision of a pan-European network was fast becoming a reality. However this took place before any networks went live. The aim to launch GSM by 1991 proved to be a target that was too tough to meet. Terminals started to become available in mid 1992 and the real launch took place in the latter part of that year. With such a new service many were sceptical as the analogue systems were still in widespread use. Nevertheless by the end of 1993 GSM had attracted over a million subscribers and there were 25 roaming agreements in place. The growth continued and the next million subscribers were soon attracted. Global usage

Originally GSM had been planned as a European system. However the first indication that the success of GSM was spreading further a field occurred when the Australian network provider, Telstra signed the GSM Memorandum of Understanding. Frequencies

Originally it had been intended that GSM would operate on frequencies in the 900 MHz cellular band. In September 1993, the British operator Mercury One-to-One launched a network. Termed DCS 1800 it operated at frequencies in a new 1800 MHz band. By adopting new frequencies new operators and further competition was introduced into the market apart from allowing additional spectrum to be used and further increasing the overall capacity. This trend was followed in many countries, and soon the term DCS 1800 was dropped in favour of calling it GSM as it was purely the same cellular technology but operating on a different frequency band. In view of the higher frequency used the distances the signals travelled was slightly shorter but this was compensated for by additional base stations. In the USA as well a portion of spectrum at 1900 MHz was allocated for cellular usage in 1994. The licensing body, the FCC, did not legislate which technology should be used, and accordingly this enabled GSM to gain a foothold in the US market. This system was known as PCS 1900 (Personal Communication System). A great success

With GSM being used in many countries outside Europe this reflected the true nature of the name which had been changed from Groupe Special Mobile to Global System for Mobile communications. The number of subscribers grew rapidly and by the beginning of 2004 the total number of GSM subscribers reached 1 billion. Attaining this figure was celebrated at the Cannes 3GSM conference held that year. Figures continued to rise, reaching and then well exceeding the 3 billion mark. In this way the history of GSM has shown it to be a great success.

Source : www.radio-electronics.com