The WiMAX e Advantage

Transcription

1 The WiMAX e Advantage An analysis of WiFi a/b/g/n and WiMAX e technologies for license-exempt, outdoor broadband wireless applications. White Paper

2 2

3 Objective WiMAX and WiFi are technologies utilized for outdoor wireless applications. Both technology standards have evolved throughout the years, offering wider coverage, higher throughput and better interference mitigation. The inherent characteristics of, and thus differentiators between WiMAX and WiFi, stem from the fact that WiMAX, as a technology, was originally designed for outdoor implementations, while WiFi was meant for indoor usage. This paper will discuss the history of these technologies and assess their differences and advantages. WiMAX and WiFi Technology Evolution IEEE is a set of standards for Wireless Local Area Network (WLAN) communication in the 2.4, 3.6 and 5 GHz frequency bands Overview The family includes over-the-air modulation techniques that use the same basic protocol. The most popular protocol versions, in terms of usage, are the b (released in October 1999) and g (released in June 2003), which are amendments to the original standard (the first wireless networking standard). The a standard (also released in October 1999) operates in 5 GHz. This carrier frequency is not as popular as the previous ones for access applications. The n group was formed in January The main objective was to achieve higher data rates in a multipath fading channel n is a recent amendment which improves upon the previous standards by adding Multiple-Input Multiple-Output (MIMO) and other new features technology performance results are commonly presented by the theoretical maximum net bit rate; quoted as 11 Mbps for b, 54 Mbps for a/g and 270 Mbps for n (MIMO 40 MHz). The actual throughput is 25-50% of the theoretical rate in an indoor environment; and in an outdoor environment, the performance is significantly reduced (depending on the topology, deployment scenario LOS/ NLOS) The indoor protocol performance also degrades as the number of users increase. IEEE , a series of broadband wireless standards, operates in licensed and license-exempt frequencies. The standard was originally designed to support Wide Area Networks (WAN), describing how wireline technologies such as Ethernet, ATM and IP are encapsulated on the air interface, and how data is classified. 3

4 Overview IEEE standardizes the air interface and related functions associated with Broadband Wireless Access systems, a key feature of is that it is a connection-oriented technology. The Subscriber Station (SS) cannot transmit data until it has been allocated a channel by the Base Station (BS). This allows e to provide strong support for Quality of Service (QoS) and the ability to support large number of users simultaneously while maintaining high service quality. The latest IEEE standard is , incorporating the IEEE e, which addresses mobile broadband wireless. This implemented a number of enhancements to , including better support for QoS, the use of scalable OFDMA, MIMO antennas and HARQ support. This standard is also called Mobile WiMAX, as its enhanced technology supports inherent mobility, enabling the subscriber to transparently roam from one base station to another. The enhanced radio features that enable mobility support also significantly increase general performance especially in high interference conditions resulting in an optimum wireless broadband solution for fixed and nomadic license-exempt networks. Technical Differences WiFi a/b/g/n WiMAX e Comments Technology Design Target Designed for (WLAN) mainly for indoor applications and small networks Designed for WAN, for outdoor applications and large networks to support fixed, nomadic and mobile applications Target Application Characteristics Indoor wireless 5 access Short distance Small network High capacity Outdoor wireless access Long distance Small/mid/large networks High capacity Mobile applications 4 (vehicular for 5 GHz) The technology can support additional applications to those mentioned here; however the performance is significantly reduced when an application has requirements out of the scope of the technology design, e.g. large number of subscribers, long distance, etc. Channel BW 5/10/20/40 MHz 5/10/20 (2X10) MHz A 40 MHz channel has limited contribution in an outdoor license-exempt deployment. In most outdoor scenarios using a 40 MHz channel will cause performance degradation when compared to a 20 MHz channel due to increased interference exposure. 4

5 Technical Differences WiFi a/b/g/n WiMAX e Comments Maximum Capacity a: 54 Mbps (20 MHz) b: 11 Mbps (20 MHz) g: 54 Mbps (20 MHz) n: 130 Mbps (20 MHz) 270 Mbps (40 MHz) e: *45 Mbps (10+10 MHz) MIMO A *80 Mbps (10+10 MHz) MIMO B *BreezeMAX Extreme 3650/5000 This is not an apple to apple comparison statistics quote the modem rate while e statistics quote user data rate n presents theoretical modem rate e incorporates more features for handling interference mitigation which reduce the total available e bit rate. The e actual bit rate is actually expected to be higher than n in most deployments scenarios due to its superior interference mitigation In general, n quotes refer to indoor performance, while e to outdoor deployments. 40 MHz cannot be implemented in most outdoor deployments due to license-exempt interference Coverage Related Features MIMO A: only in n MIMO A HARQ CTC The e link budget is better in 5 db compared to n, thus wider coverage is supported OFDM OFDMA The e OFDMA support handles NLOS in a more efficient manner and enables wider coverage when compared to

6 Technical Differences WiFi a/b/g/n WiMAX e Comments Interference Mitigation MIMO A: only in n, and not implemented on most chipsets available (as they are designed for indoor) OFDM Overcoming short range multipath FFT 64 (3.2µsec), Guard Interval 0.8µsec MIMO A OFDMA Overcoming long range multipath FFT 1024 (90µsec), Guard Interval 11µsec HARQ Scheduled protocol OFDMA provides each user best performance according to the link quality (location and propagation characteristics), thus overcoming fading and interference challenges based on each user while maintaining its maximal performance As e is targeted for outdoor deployments it supports 13 times multipath distance comparing to n HARQ is a state-of-the-art error detection and correction method that significantly improves the link performance and reliability The e scheduled protocol significantly increases interference resistance compared to the CSMA protocol QoS Limited to AP s local QoS WMM/WME 4 access categories: voice, video, best effort, and background Limited MIR/CIR support Network-wide advanced QoS Connection-oriented Centralized control Scheduled protocol 5 QoS classes: UGS, ertps, rtps, nrtps, BE CIR/MIR support The e QoS is a network wide mechanism taking into consideration the load and prioritization in the entire network The QoS mechanism is local to the AP and to the subscribers connected to it. The QoS mechanism considers the complete network The 02.16e QoS performance is expected to perform better in an outdoor license-exempt deployment challenged by high traffic, mixed applications and interference 6

7 Technical Differences WiFi a/b/g/n WiMAX e Comments Number of Subscribers Limited High In an network, aggregated throughput is expected to be decreased as more subscribers are added due to packet collisions In an e network traffic is centrally managed and scheduled. Adding more subscribers does not degrade the total aggregated throughput Conclusion e and n are examples of two leading wireless technologies evolving and improving with the addition of new features and enhanced radio techniques. The core technology and its original target applications greatly influence the performance that can be achieved in different scenarios n, which was originally designed for indoor applications, offers higher potential bit rate. The benefit of this high bit rate can be achieved only in small, indoor wireless networks. Performance is expected to be significantly reduced in a large, outdoor deployment e was originally designed for large, outdoor deployments by reserving more bandwidth to overcome the outdoor challenges. Its superior radio techniques and QoS mechanism enable maintaining high performance and better control of network traffic. Theoretically n may present higher performance than e, but actual deployments indicate that high throughput can only be achieved in an indoor deployment or in limited scenarios of outdoor deployments. In standard and complex outdoor deployments, e technology is designed to provide better performance utilizing its enhanced radio and QoS capabilities that were originally designed for the more challenging, outdoor deployments. 7

8 Headquarters International Corporate Headquarters North America Headquarters Sales Contacts Australia: Brazil: Canada: Caribbean: China: Czech Republic: France: Germany: Italy: Ireland: Japan: Latin America: Mexico: Nigeria: Philippines: Poland: Portugal: alvarion.com Romania: Russia: Singapore: South Africa: Spain: U.K.: Uruguay: For the latest contact information in your area, please visit: About Alvarion Alvarion (NASDAQ:ALVR) is a global leader in 4G wireless communications with the industry s most extensive customer base with hundreds of commercial WiMAX deployments. Alvarion s industry leading solutions enable true open 4G and vertical applications for service providers and enterprises. Through an OPEN WiMAX strategy, superior IP and OFDMA know-how, and ability to deploy large scale end-to-end turnkey networks, Alvarion is delivering the true 4G broadband experience today ( Copyright 2010 Alvarion Ltd. All rights reserved. Alvarion its logo and all names, product and service names referenced herein are either registered trademarks, trademarks, tradenames or service marks of Alvarion Ltd. in certain jurisdictions. All other names are or may be the trademarks of their respective owners. The content herein is subject to change without further notice. WiMAX Forum is a registered trademark of the WiMAX Forum. WiMAX, the WiMAX Forum logo, WiMAX Forum Certified and the WiMAX Forum Certified logo are trademarks of the WiMAX Forum rev.a