Comparative analysis of new high data rate wireless ... analysis of new high data rate wireless communication technologies “From Wi-Fi ... GSM) and the arrival of ... new high data

Comparative analysis of new high data rate wireless communication technologies “From Wi-Fi to WiMAX”

Nicolas Fourty, Thierry Val, Philippe Fraisse, Jean-Jacques Mercier

Research Team ICARE EA 3050 1, Place Georges Brassens – BP 60073 - 31703 Blagnac

FRANCE

E-mail: {fourty, val, mercier}@iut-blagnac.fr ; [email protected]

Abstract The aim of this paper is, by a precise description of the

different existing and developing wireless networks, to determine how all these networks may collaborate together. The example taken is WiMAX which has been able to examine advantages and weaknesses of existing WLAN in order to determine a specific application type. The confrontation of WiMAX and Wi-Fi characteristics will highlight evolutions in wireless networking and will give us keywords of what new networks are attended for.

1 Introduction

Nowadays numbers of wireless standards are available. There is no perfect technology and each one represents a compromise between different factors like range, data rate, temporal constraints… The choice of one particular technology depends on what we want to do with it. Recent studies have significantly increased network efficiency and new networks show the way for new users and possibilities. In the first part of this paper, we will examine and try to classify wireless networks in order to underline progress in both technologies and concepts. Then, we will confront the new WiMAX standard to a well known WLAN, Wi-Fi. The analysis results should help us understand what has motivated the apparition of these technologies and how new kinds of networks may converge with older ones. The last part concludes and presents our laboratory’s WiMAX project in collaboration with Interactive Device.

2 Wireless network classification

The first distinction between wireless networks is their range. Four network types are defined according to their range:

WPAN, Wireless Personal Area Network; WLAN, Wireless Local Area Network; WMAN, Wireless Metropolitan Area Network;

WWAN, Wireless Wide Area Network. The current architecture which authorizes connections

between personal equipment and the worldwide network is composed of different network types. At each level, from personal to global, data can be sent through wired or wireless networks. In addition, range depends on the power that the emitter can deliver however this power is limited. The limitation isn’t limited by the technology but is a political will. It may vary from one country to another. In France, for example, it’s the Telecommunications Regulation Authority (ART) which determines the maximal power in each frequency band.

In order to perfectly understand the differences between network types, it’s important to make a second distinction, between with or without signalization protocol networks:

Networks with signalization protocol have been implemented by telecommunications operators for telephony. This kind of network today grants us, for example, to trade data between cell phones (3G);

Local area networks, like Ethernet are called networks without signalization. Internet is the perfect example of the utilization of this kind of networks. Networks with signalization protocol can ensure a

fixed bandwidth in a circuit switching mechanism and give the possibility to get a fixed QoS for packet transmission. Once a connection has been established, a circuit switching mechanism connection is fully dedicated for exchanges between the source and the receiver whereas, in a packet transmission network, the connection is often a virtual circuit. In networks without signalization, the packets exchanged share the same bandwidth. The advantages of this kind of network are simplicity and the easy way to implement and deploy the network.

A third and last distinction to be made in wireless networks, which should take an increasing importance in the next years is cell switching. It concerns the topology needed for a network or a user to go through one cell to another. There are three cell interconnection methods:

Proceedings of the Joint International Conference on Autonomic and Autonomous Systems and International Conference on Networking and Services (ICAS/ICNS 2005) 0-7695-2450-8/05 $20.00 © 2005 IEEE

Networks with infrastructure require another technology (often wired) to interconnect each access point for each cell. This makes it possible to constitute a wider network;

In the “Mesh” networks, the access points are sufficiently close “to be seen” and can communicate with one another without requiring additional infrastructures;

Lastly, in “Ad hoc” networks, there are no more access points. The different equipment can be used as relays to propagate information from one cell to another. Each piece of equipment constitutes its own cell which communicates with the others.

2.1 Wireless Personal Area Network (WPAN)

Personal networks are used to connect various devices in a small area. Today, the most known of WPAN is Bluetooth (IEEE 802.15.1). Two new technologies are on the industrial starting line: one allowing a high data rate UWB, and the other Zigbee, allowing low cost, low power device interconnections.

2.1.1 Bluetooth. The technology, firstly developed by the Sweden Ericsson makes it possible to make a master device communicate with 7 other slave devices. It is mainly designed to replace the wires which connect devices and peripherals. It is possible to constitute a maximum of 10 groups (80 devices in theory) in the same area. This kind of connection is dedicated to replace point-to-point connections or to interconnect two devices (personal assistant, telephone, microcomputer...).

Today standardized under the name IEEE 802.15.1, in its last version 2.0+EDR it allows data rates up to 3Mb/s with up to 100 meters range. It uses the 2,4 GHz ISM unlicensed band also used by Wi-Fi.

2.1.2 Ultra Wide Band – UWB. The new Ultra Wide Band standard uses a great part of the spectrum to exchange data. Signal for each frequency band is thus very weak and does not disturb the other signals which are on their own band (Wi-Fi, etc.). The UWB is standardized under the name IEEE 802.15.3 and makes it possible to transmit several hundreds of Mb/s on a few tens of meters (when 6 UWB systems are interacting together in the same area, with a 50 Mb/s maximum capacity each).Recent work should permits to extend the range of UWB allowing it to compete with wireless LAN.

2.1.3 Zigbee. Zigbee is a network to mainly transmit commands but no important data streams. It allows WPAN very low-cost implementation. There are two versions of Zigbee:

IEEE 802.15.4 which allows to communicate at 250 Kb/s up to 10 meters to interconnect a maximum of 255 devices (2,4 GHz unlicensed band);

IEEE 802.15.4a which is limited at 20 Kb/s but allows an increased range until a maximum of 75 meters to interconnect up to 65 000 devices (900 kHz band). Zigbee is particularly adapted to the communication

from object to object which does not require great data rates but whose cost must allow its integration in a great number of devices. Autonomy can be two years with standard alkaline piles. The objective of Zigbee is to make it profitable to make a simple bulb communicating.

2.1.4 RFID. Although RF chips have only very little computing power in general, RFID however allows extremely low price communications between objects. RFID chips don’t have any IP stack, but transmit a simple identifier. However in the long term we could see the fusion of the two protocols with the rise in power of the RFID chips and price decrease of Zigbee networks. RFID technology allows a range of 3 m in the case of passive chips (not requiring power amplifiers).

RFID are in the course of standardization in the EPC global consortium with the first EPC 1.0 standard published in September 2003 (Electronic Product Codes).

2.2 Wireless local area network (WLAN)

These last years, the explosion of Wi-Fi devices made discover the wireless network world. In the WLAN field, only Hiperlan II tries to compete with it. However rise in power of personal networks, until now limited to a few meters, shows inclinations to break the barriers (it was the case with the advertisements of Bluetooth 2.0 only published in November 2004 or more recently with the evolutions of UWB). Controversially, Wi-Fi was used at the metropolitan level because of the lack of more suitable wireless networks until now.

The Wi-Fi standard family allows to establish wireless network on short distances. These standards are sometimes associated with directional antennas to establish point-to-point connections (for example to interconnect Wi-Fi hot spots while waiting for the arrival of WiMAX).

Wi-Fi network types, well adapted for itinerancy, are badly adapted for mobile networks (moving devices). Beyond a few kilometers per hour, they take down.

It exists several types of Wi-Fi networks: IEEE 802.11 the first standard of the series in

frequency hopping spread spectrum (theoretical data rate 2 Mb/s);

IEEE 802.11b: theoretical data rate 11 Mb/s - range of 100 m to a maximum of a few hundreds meters - 2,4 GHz unlicensed band. This standard has allowed the rising of wireless networks these last years;

IEEE 802.11a: theoretical data rate 54 Mb/s (but decrease with the distance more quickly than 802.11b)


- range of about thirty meters - 5 GHz band; IEEE 802.11g: theoretical data rate 54 Mb/s - range of

a hundred meters - 2,4 GHz unlicensed band; IEEE 802.11n: theoretical data rate 320 Mb/s - about

thirty meters range - uses two bands 2,4 and 5 GHz. QoS is included in the standard 802.11n just (standard IEEE 802.11e). This standard should appear during 2005.

Extensions: IEEE 802.11e: QoS extension; IEEE 802.11f: extension for managing handover

(passage from one cell to another without cut); IEEE 802.11i: security extension.

2.3 Wireless metropolitan area networks (WMAN) and 3G mobile networks

Wireless networks adapted for covering cities and villages, arrived a few years after the Wi-Fi type WLAN. Three large families must or have already taken off:

2.3.1 WiMAX. WiMAX (World Interoperability for Microwave Access) is the name of a mark intended for labeling compatible equipment with American IEEE 802.16 standard and European ETSI HiperMAN standard. Its theoretical data rate is 70 Mb/s with a range of up to a maximum of 50 km. The first tests have been done in 2004 and availability in volume should be for 2005. WiMAX protocol makes the study of a detailed description in the third section of this paper.

2.3.2 3rd generation mobile networks. This time, the objective is to allow the use of the network in a mobility situation (in displacement) whatever the speed of the vehicle or almost. 3rd generation mobile networks (3G) are national networks but whose cell size requires the installation of equipment in each city concerned.

After the first generation (analogical mobile phones), the second generation (numerical mobile phones such as GSM) and the arrival of data transmission with the GPRS (sometimes called 2,5G), 3G mobile networks combine at the same time voice and data transport with high data rate. The standardization of 3G mobile systems is coordinated within the whole of IMT-2000 standards from the International Union of Telecommunications.

There are several 3G standards for mobile telephony: UMTS, followed by the 3GPP consortium (3rd

Generation Partnership Project), with a theoretical data rate up to 2 Mb/s even if the first deployments are done at 384 Kb/s. There are in fact two great types of UMTS, according to the radio interface used: W-CDMA or TD-CDMA. Unfortunately, the choices of Europe and Japan on the one hand and of China on the other are incompatible;

CDMA 2000, followed by consortium 3GPP2, also

allows a maximum theoretical data rate of 2 Mb/s. It exists several evolutions such as 1X RTT and the 3X, but it is especially the versions which take better into account the mobile Internet which are the most promising: CDMA2000 EV-DO (EVolution - Data Only) and EV-DV (EVolution – Data and Voice);

EDGE (Enhanced Data rates for Global Evolutions) is an evolution of the GPRS which allows data rates of 384 or 200 Kb/s according to the version with a maximum of 474 Kb/s. It makes it possible to preserve upward compatibility GSM/GPRS in its version “EDGE Classic”. “EDGE Compact” version enables to use reduced frequency bands (lower than 1 MHz).

2.3.3 MBWA. “Mobile Broadband Wireless Access” is a standard under development: IEEE 802.20. It should allow the installation of mobile metropolitan networks with speeds going up to 250 km/h.

MBWA uses frequency bands with license below 3,5 GHz. It allows maximal data rates by users of 1 Mb/s downlink and 300 Kb/s uplink with cells of a maximum range of 2,5 km. A version using a 5 MHz channel could allow data rates of 4 Mb/s downlink and 1,2 Mb/s uplink for each user. MBWA is well adapted to mobility voice and data with terminals focused on data (compared to 3G mobile networks which are focused on the voice). The standard allows a short latency for the data. It should use well controlled technologies (frequency hopping, OFDM, adaptive antennas...).

Compared to MBWA, WiMAX is limited to a lower mobility (60 km/h against 250 km/h). Compared to the projects of mobile telephony (3GPP based on GSM interface and 3GPP2 based on the IS-41 interface used for example in CDMA1), MBWA is optimized for IP data. One of the objectives of MBWA is to propose a better spectral effectiveness, higher than 2 bits/sec/Hz/cell at 3 km/h and higher than 1,5 bits/sec/Hz/cell at 120 km/h downlink, the uplink with a lower effectiveness of 25 %. That is to say much more than 3G mobile system effectiveness (0,5 bit/sec/Hz/cell for CDMA EV-DO). The QoS will be integrated in the standard and a “pure IP” logic should facilitate voice and data transport.

However, IEEE 802.20 standard which will be used by MBWA is still at a preliminary stage. It was initialized in March 2002. Last discussions on the planning of the project envisage a first vote in July or October 2005 and a standard published in May or December 2006.

2.4 Wireless Wide Area Network

Satellite allows cells with the size of several countries and facilitates the access to the Internet in the non accessible rural zones.

According to the satellite altitude, several types of


networks can be defined: Geostationary satellites (GEO), located at 35 800 km

of the ground, they remain in the same position in the sky. Now, it exists satellites allowing a bidirectional access using DVB-S standard downlink and more and more often DVB-RCS standard uplink. The equipment prices and band-width are variable according to technology used;

Low orbit satellites (LEO) require sending a “constellation” of satellite in order to have a complete cover of the ground surface. After a difficult beginning, constellations of satellites, found commercial applications like telephony for example;

Satellites in average orbit (MEO) could in the long term constitute a good compromise between the need for a reduced number of satellites and the proximity of the ground which allows less power consumption and reduced latency times.

3 A wireless network web The interconnection between all the types of networks

presented is announcing the will to offer “seamless networks”. Handover (passage without cut of a cell to adjacent one) and roaming (agreement between operators to reach their respective networks) allow to constitute this network web. This web permits, whatever the technology used on all the scales, to be able to reach the network everywhere and whenever you want. It is precisely the objective of the new working group IEEE 802.21 “Media Independent Handover Interoperability” which aims at the standardization of these handovers that one called “vertical handovers” and whose first meeting took place in March 2004. In this point of view, the various types of networks presented previously would have to cohabit to be complementary and try to carry out the objective of a total wireless Internet.

The transparent passage from one network to another represents less a technical objective than a marketing one: the strategies which will be chosen by operators will determine the user’s ability to pass from one local area

network to a metropolitan or long distance network in more or less a transparent way.

3.1 The WiMAX study case

An example of the will to take into consideration the advantages and the weaknesses of each network in order to mesh networks together is WiMax.

3.1.1 Detailed description of WiMAX. IEEE 802.16 standard and the HiperMAN network developed in Europe by the ETSI (European Telecommunications Standards Institute) are pushing towards a convergence and inter-working between the two standards.

It mainly does not act to allow the direct access but rather to interconnect the various access points on a city scale: for example, Wi-Fi hot spots or residential DSL. WiMAX makes it possible to obtain a connectivity of the same type as the rented lines used by telecommunications operators for the Internet or telephony transport: T1 (for the American suppliers or Japanese 1,544 Mb/s) or E1 (for the European suppliers 2 Mb/s, 50 km maximum). WiMAX, with a theoretical data rate of 70 Mb/s in 20 MHz channels, allows a few hundreds of DSL connections. The maximum range envisaged is about 50 km. It will be necessary in practice to envisage rather 20 km and even 8 km when there are obstacles

It exists 3 frequency bands which can be used in WiMAX

Fig. 2. Spectral representation of WiMAX bands. ISM: Industrial, Scientific and Medical Band UNII: Unlicensed National Information infrastructure band.

Fig. 1. Example of a WiMAX deployment.

TABLE I COMPARATIVE ANALISIS OF AVAILABLE WIRELESS NETWORKS

Commercial name Standard Theoretical

data rates Max

Range Frequency

(GHz)

RFID EPC 1.0 -ISO 10536 and ISO 14443 106 Kb/s 3 m several

Bluetooth IEEE 802.15.1 2 Mb/s 100 m 2,4 UWB IEEE 802.15.3 Up to50 Mb/s 10m Zigbee IEEE 802.15.4 250 Kb/s 10 m 2,4 Zigbee IEEE 802.15.4a 20 Kb/s 75 m 0,9 Wi-Fi IEEE 802.11b 11 Mb/s 100m 2,4 Wi-Fi IEEE 802.11a 54 Mb/s 30 m 5,5 Wi-Fi IEEE 802.11g 54 Mb/s 100 m 2,4 Wi-Fi IEEE 802.11n 320 Mb/s 30 m 2,4 - 5,5

WiMAX IEEE 802.16a 70 Mb/s 50 km 2,5 - 3,5 -5,8 MBWA IEEE 802.20 1 Mb/s 100m <3,5


(lower than 11 GHz as described in standard IEEE 802.16-2004):

5,86 GHz (unlicensed band); 2,5 and 3,5 GHz (bands requiring a license); A 2,4 GHz unlicensed band should be added

3.1.2 Wi-Fi versus WiMAX. WiMAX and Wi-Fi are not addressed to the same market but are very complementary:

Wi-Fi allows implementing a wireless local area network for a house or a small building. It can also be used to carry out a public hot spot allowing mobile points to connect in a hotel, an airport, etc.;

WiMAX is a metropolitan technology whose objective is to interconnect houses, buildings or even hot spots to allow communication between them and with the remainder of networks (Internet, etc). Although not being targeted on the same use, more

recent WiMAX technology, have several advantages compared to Wi-Fi. It denotes progress carried out in a few years in the wireless networks:

A better reflection tolerance; A better penetration of obstacles; An increased number of interconnections (a few

hundreds of equipment rather than some tens of equipment for Wi-Fi). The MAC layer (Medium Access Control) used by

WiMAX is based on a slotted time division mechanism to allow a homogeneous distribution of the bandwidth between all the devices (TDMA) which is more effective and support several channels compared to the mechanism used by Wi-Fi (CSMA-CA very close to the CSMA-CD used by Ethernet networks). This makes it possible to obtain a better occupation optimization of the radio spectrum: it is said that its effectiveness (bits/seconds and by Hertz) is better. Thus, WiMAX has an effectiveness of 5 Bps/Hz compared to the 3,2 Bps/Hz of MBWA or 2,7 Bps/Hz of Wi-Fi. Thanks to this excellent effectiveness and associated with an adapted coding and modulation, it becomes possible to transmit 100 Mb/s in a channel of only 20 MHz.

3.2 Wi-Fi and WiMAX differences

3.2.1 PHY layer. Already on the PHY layer, 802.16 allows adaptive RF channel bandwidths and reuse of these channels (frequency reuse) to increase the cell capacity when the network grows. The standard also specifies support for automatic transmit power control and quality measuring instruments in order to get the best cell deployment and the most effective use of the spectrum. Operators can re-allocate spectrum by dividing the cell into sectors when the number of subscribers increases. Moreover, modularity of channel bandwidth allows the

manufacturers equipment to be adapted to various spectrum attribution rules imposed by governments.

Products based on Wi-Fi require at least 20 MHz for each channel (22 MHz in the 2,4 GHz band for 802.11b), and use only license free bands 2,4 GHz ISM, 5GHz ISM and 5 GHz UNII. The Wi-Fi spectral efficiency is well below the WiMAX one with 2,7 bps/Hz compared to 5,0 bps/Hz. In the 802.11 MAC layer, which is based on CSMA/CA, such an important scalability isn’t allowed. Like with a traditional Ethernet LAN, the consequence of a number of user increase, is a geometrical reduction of throughput. In contrast the MAC layer in 802.16 standard was designed to authorize hundreds users with only one RF channel, contrary to the 802.11 MAC layer.

3.2.2 The Range. The BWA Standard is designed to guarantee optimal performances in all kinds of propagation environments (LOS, NearLOS and NLOS), and to even provide robust performances in difficult cases. transmissions and to reduce the multi-path effects resulting from the reflections

Modulation OFDM has a high spectral effectiveness on ranges going from 2 to 40 km and providing data rates of 70 Mb/s with only one RF channel. Mesh topologies and antenna techniques (STC, antenna diversity) can be used for still improving cover. The OFDM designed for the BWA is different from the others by the fact that it is optimized for long range transmissions and to reduce the multi-path effects resulting from the reflections. The OFDM designed for the BWA is different from the others by the fact that it is optimized for long range. The OFDM designed for the BWA is different from the others by the fact that it is optimized for long range transmissions and to reduce the multi-path effects resulting from the reflections. In contrast, WLAN and systems based on 802.11 have a basic CDMA and OFDM approach with a quite different vision, requiring low power consumption of energy and implying a limited range. The OFDM in the WLAN were created with the vision of systems covering hundreds meters. 802.16 is designed for high power OFDM use allowing deployments on tens of kilometers.

3.2.3 The QoS. QoS of 802.16 is based on a Grant/Request mechanism. It is configured to have various service levels (for example, T1/E1 devoted to business and “Best Effort” to residential).The protocol uses TDM data stream downlink and TDMA uplink, which allows the management of delay-sensitive services like voice and video.

By ensuring that the data reach the channel without collision to, 802.16 improves the spectral effectiveness, in comparison of access techniques based on CSMA-CA used in WLAN. 802.16 also ensures bounded delays (CSMA-CA, on the other hand, offers no guarantee).The


TDM/TDMA access technique also allows the easiest support for multicast and broadcast.

4 Conclusion and perspectives

To conclude, it’s obvious that the WiMAX standard

goal is not to replace Wi-Fi in its applications but rather to supplement it in order to form a wireless network web. By a vertical handover (seamless networks) or by a horizontal handover, the general tendency of wireless networks goes towards an always improved cover while being connected on the principle of the “best effort”. Emergent technologies come to occupy space, left open by older technologies and are intended for very precise applications (low power consumption, long range, important data rates). In this wireless network “customization” a common will emerge. The desire to implement the QoS in the network in the lowest protocol

layers in order to be able to control transmission delays and to be able to offer services such as the voice and video which are applications very sensitive to temporal constraints.

WiMAX in this direction isn’t and won’t be a Wi-Fi “MAX” (for “improved” or “enhanced”) but will open the way for new long distance applications needing bounded delays, such as telephony for example. In this direction, our lab in collaboration with Interactive Device (a French company which has experience in developing and producing wireless communicating devices), is currently developing a project based on WiMAX and its future evolution (including mobility). The goal of this project (code name WiCall) is to simulate and develop a WiMax-certified, thin-client handheld device using WiMax-enabled silicon. The second objective is to design a scalable WiMax end-to-end solution for mobile VoIP telephony with customer care managed by a telecommunication operator.

REFERENCES

[1] Specification of the Bluetooth System – core package: 2.0 + EDR, 04 November 2004.

[2] M. van der Zee, G. Heijenk, “Quality of Service in Bluetooth Networking” FCP NB 102 88 Uen , 03 January 2001.

[3] S. El Homsi, E. Campo, T. Val and J.J. Mercier, “An original solution for Bluetooth wireless synchronous communication dedicated to a sensors and actuators system”, ISIE2004, 03 - 07 May 2004.

[4] T. Val, P. Fraisse, D. Andreu, “Vers l'utilisation de Bluetooth pour la commande à distance de robots mobiles” international revue JESA, Vol. 37 – n° 7-8/2003, pp. 859-892, January 2004

[5] 802.16-2004 IEEE Standard for Local and metropolitan area networks Part 16: Air Interface for Fixed Broadband Wireless Access Systems, 01 October 2004

[6] C. Eklund, R. B. Marks, K. L. Stanwood, S. Wang, “A Technical Overview of the WirelessMAN Air Interface for Broadband Wireless Access” IEEE 802.16 technical tutorial, 02 June 2004, http://www.ieee802.org/16/

[7] “WiMAX’s technology for LOS and NLOS environments” Wimax Forum white paper, contributors Eugene Crozier (SR Telecom); Allan Klein (SR Telecom) http://www.wimaxforum.org/technology/White_Papers/

[8] “Wi-Fi certified for WMM”, Wi-Fi alliance white paper, http://www.wi-fi.org/OpenSection/MediaResources.asp

[9] A. van den Bossche, “A short metrology of Zigbee”, Zigbee white paper unpublished.

TABLE II NETWORKS CONFRONTATION

802.11 802.16

Scal

abili

ty

Fixed wide channels (20MHz)

MAC designed to support tens of users

Adaptative channel bandwidth (sectorization)

Scalable bandwidth from 1.5 MHz to 20 MHz. MAC independant of the channel bandwidth.

MAC designed to support hundreds of users

QoS

Contention-based MAC (CSMA/CA). No guaranteed QoS

Standard cannot currently guarantee latency for Voice, Video (PCF not implemented)

Standard does not allow for differentiated service levels for each user

TDD only – asymmetric

802.11e (proposed) QoS is prioritization only

Grant-request MAC

Designed to support Voice and Video

Supports differentiated service levels: T1 for business customers, best effort for residential

TDD/FDD/HFDD – symmetric or asymmetric

Centrally-enforced QoS

Ran

ge

Optimized for ~100 meters

No distance compensation

Designed to handle indoor multi-path (delay spread of 0.8µs)

Optimization centers around PHY and MAC layer for 100m range

Range can be extended by cranking up the power – but MAC may be non-standard

Optimized for up to 50 Km

Designed to handle many users spread out over kilometers

Designed to tolerate greater multi-path delay spread (signal reflections) up to 10.0µs

PHY and MAC designed with multi-mile range in mind

Standard MAC

Cov

er

Optimized for indoor performance

No mesh topology support within ratified standards

Optimized for outdoor NLOS performance

Standard supports mesh network topology

Standard supports advanced antenna techniques

Secu

rity

Existing standard is WPA + WEP

802.11i in process of addressing security

Triple-DES (128-bit) and RSA(1024-bit)


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Comparative analysis of new high data rate wireless ... analysis of new high data rate wireless communication technologies “From Wi-Fi ... GSM) and the arrival of ... new high data