Towards a Wi-Fi Ecosystem

8/8/2019 Towards a Wi-Fi Ecosystem

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Towards a Wi-Fi Ecosystem:

Technology Integration and Emerging Service Models1

Vinoth Gunasekaran Prof. Fotios C. Harmantzis2

Stevens Institute of Technology

Wesley J. Howe School of Technology Management

Telecommunications Management

Castle Point on Hudson

Hoboken, NJ 07030, USA

Phone: +1 (201) 216 - 8279

Fax: +1 (201) 216 5385

Email: {vgunasek, fharmant}@stevens.edu

1

This paper is based upon contributions of the respective authors to the following conferences during 2005: 9th

IFIP/IEEEInternational Symposium on Integrated Network Management (IM) in Nice, France, 61 st IEEE Semi-annual VehicularTechnology Conference (VTC) in Sweden, Stockholm, and 6 th World Wireless Conference (WWC), in SF Bay Area, USA. Weare thankful to the conference participants and anonymous referees for useful feedback at the earlier stages of this research. Inparticular, we would like to thank Dr. N. K. Shankaranarayan and Dr. Byoung Jo J. Kim, both with AT&T Labs, NJ, USA, fortheir valuable comments and understanding the economics and technical aspects of emerging technologies (Mr. Gunasekaranspent the summer of 2004 working with them in AT&T Labs). Finally, many thanks to Dr. A. Curtis and Dr. K. Ryan, both atStevens Institute of Technology, and Dr. George Thomas at the University of Louisiana, for their valuable input regardingtechnological and other details of wireless networks.

2Corresponding Author: Dr. Fotios Harmantzis, Assistant Professor, Head of Performance and Economics ofTelecommunications Networks research team, School of Technology Management, Stevens Institute of Technology.


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Towards a Wi-Fi Ecosystem, Telecommunications Policy 2

Abstract:Wi-Fi currently has emerged not only as a dominant standard for wirelessLocal Area Network (LAN) but also as the wireless Personal area Networks (PAN)

and Metro Area Network (MAN). There is clearly a widespread support for metro

area Wi-Fi around the world and the experts believe that city wide Wi-Fi could

make ubiquitous broadband a reality. Wi-Fi networks are getting integrated with the

Internet and cellular infrastructure, offering innovative services (data and voice) to

the individuals and businesses. In the metro area network we believe that a

integration of WiMAX and Wi-Fi technologies will provide the most cost effective

solution of backhaul and access for both voice and data services. In the cellular

arena, as mobile operators are looking for new ways to connect, Wi-Fi can easily be

integrated with the existing mobile data networks (2.5G/3G), leading to the

expansion of an organized wireless ecosystem. On the other hand, due to the

emergence of multimode devices, the next step is the integration of heterogeneous

wireless networks. This paper outlines the emerging business models of

heterogeneous wireless networks that are mainly Wi-Fi centric, proposing new

service models.

Keywords- Strategy, Integration, Wi-Fi, WiMAX, Bluetooth, GSM/CDMA,

VoWi-Fi


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1. Introduction

Wi-Fi is widely accepted since it introduces the flexibility of wireless access into

any small office, home, enterprise, restaurant or school, and the cities where

ubiquitous wireless is becoming a reality. There are various types of Wi-Fi

deployments which can be summarized as follows [5]: The first type is the

deployment at home, businesses and enterprises where the service is offered without

charge. The second type is offered by micro carriers, e.g., Starbucks coffee-shops

and Border bookstores in the United States [9]. Carriers set up their own access

points and maintain customer and billing relationship with subscribers. Though

revenues are not high, the model is still profitable for small business owners. The

third type is offered by Wi-Fi startup companies3 that aggregate micro carriers

network and provide a single access service to the end user. The fourth type applies

to Wi-Fi services offered by cellular operators4. They can partner with the micro-

carriers or aggregators or they can roll-out their own Wi-Fi network and integrate it

with their cellular network. The fifth type is the deployment of a city wide Wi-Fi

network by an individual WISP or a municipality/city5 (public sector) or a mix of

public and private sector partnership.

A city wide Wi-Fi deployment is emerging as the modern high-tech economic

development tool in both developing and developed countries. In some cases, even if

the city authorities aim to improve the overall efficiency of the government services

and deliver lower-cost Wi-Fi Internet services to communities and businesses, there

3 www.boingo.com4 www.t-mobile.com5 http://www.muniwireless.com/reports/docs/June2004Report.pdf (URL accessed on Feb 2005)


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is still opposition from various fronts, trying to prevent cities from sponsoring their

own Wi-Fi networks. The telecom companies in the United States are also

concerned about their dominance over local markets, as local governments are trying

to build their own affordable wireless broadband network, e.g., Wi-Fi. However, city

authorities have realized that city wide Wi-Fi is a strategic investment as it provides

an infrastructure that can provide internet access to low income citizens and small

businesses at affordable price, thereby bridging digital divide6.

Since Wi-Fi is just an access technology it has to be integrated with other backbone

wired and wireless networks. In some cases it has also been integrated with other

access technologies on a complementary basis. There are many new advancements

and innovations in Wi-Fi. However, it is necessary to investigate how Wi-Fi

interoperates with others on an integrated environment. In a heterogeneous wireless

environment, it is assumed that interoperability exists between network devices and

the networks they are connecting to. International standard bodies and vendor

groups are formed to set up standards on how one technology interoperates with

another in a heterogeneous wireless environment. Emerging wireless technologies

that become main-stream are typically more evolutionary than revolutionary. A

technology cannot succeed by itself; it must interoperate with other technologies on

a complementary basis solving different purposes. One such technology is Wi-Fi

6The digital divide is both a social and political issue addressing the gap bettwen the communities that have accesss to internetand those who do not. We have to address three main issues in bridging the Digital Divide; Affordability, Availability, andAccessibility of services and applications. Wi-Fi is one such technology that can address all these three issues.Cities/Municipalities have to build a communication infrastructure that is affordable and available all the time every-where tooffer small businesses and low-income households.


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and we are witnessing it now: Wi-Fi with 2.5G & 3G, Wi-Fi with WiMAX, Wi-Fi

with VOIP (VoWi-Fi), Wi-Fi with Bluetooth, etc.

Although we are witnessing market maturity in certain wireless technologies,

more research on integration and interoperability of wireless technologies need to be

done. This paper attempts to present emerging business models of Wi-Fi integration

with PAN, MAN and WAN. We believe that this is the first time that an emerging

service model of Wi-Fi integrated with cellular, WiMAX, VoIP, and Bluetooth, i.e.,

a Wi-Fi ecosystem, has been proposed and unique insights are presented. The other

main goal of this article is to compare and contrast Wi-Fi with other wireless

technologies that are likely or have been already integrated with Wi-Fi. From an

integration point of view, we believe that Wi-Fi is the winning technology in such a

wireless ecosystem. That integration brings not only technical issues but also

business and policy related issues.

2. Some Background of Wireless Technologies

2.1 Overview of WLAN-Wi-Fi7

(IEEE 802.11)

7Wi-Fi, or Wireless Fidelity, allow to connect to the internet from virtually anywhere at speeds of up to 54Mbps. Wi-Fi -enabled devices use radio technologies based on the IEEE 802.11 standard to communicate data anywhere within the range ofan access point. The Wi-Fi Alliance formerly known as WECA is the global Wi-Fi organization that created the Wi-Fi brand.A nonprofit organization, the Alliance was formed in 1999 to certify interoperability of IEEE 802.11 products and to promotethem as the global, wireless LAN standard across all market segments. www.wi-fi.org.


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The 802.118

is a WLAN standard developed by the IEEE and it was officially

accepted in 1997. IEEE 802.11 operates in the unlicensed 2.4 GHz ISM band with a

total available bandwidth of 83.5 MHz (2.4GHz - 2.4835 GHz). As seen in Table 2

IEEE 802.11 defines a group of WLAN standards that includes original 802.11,

802.11a, 802.11b, 802.11e, 802.11g, 802.11h , 802.11i, 802.11k, 802.11n, 802.11r

and 802.11s. The first IEEE 802.11 standard published in 1997 described only the

MAC (Medium Access Control) and PHY (Physical Layer). The other 802.11

standards are either enhancements to the original MAC for QoS (Quality of service)

and security, or extension to the original PHY for high-speed data transmission.

IEEE 802.11g offers further high-speed extension in the 2.4 GHz band. It uses

OFDM in the 802.11b frequency band (2400-2485.5 MHz) and it has a maximum

data rate of 54Mbps. 802.11g is backward compatible with 802.11b and it includes a

technique for prioritizing data packets to improve quality of streaming media, such

as VoIP, voice, and video conferencing. 802.11a uses 5 GHz unlicensed U-NII

spectrum. Since it is not compatible with 802.11b, dual-band access points are used

to facilitate the coexistence of 802.11a and 802.11b networks.

802.11e defines Quality of Service and it supports streaming traffic and audio video

applications. 802.11f standardizes the inter AP protocol for transmitting between

access points. 802.11h deals with the spectrum and transmit power control. 802.11i,

also called Wi-Fi Protected Access, supports a more advanced encryption standard,

along with 802.1x authentication and key management features. 802.11k is for radio

resource management and will provide power measurement information for access

8 http://grouper.ieee.org/groups/802/11/index.html


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points and switches to make wireless LANs run more efficiently with less

interference. 802.11n standard aims enhancements for higher throughput, designed

to raise efficient WLAN throughput to more than 100Mbps. 802.11r is for fast

roaming and will address maintaining user connectivity from one access point to

another while maintaining high QoS for applications like VoWi-Fi. 802.11s standard

will deal with mesh networking and it is not expected to get ratified in the near

future as it is in a premature stage.

2.2. WPAN (Bluetooth)-IEEE 802.15.19

This technology enabled the mass replacement of many of the short-range cables we

use today. It is convenient because of its easy-to-use and ad-hoc networking

[3]. Bluetooth is a worldwide open standard, short-range radio specification focused

to replace device cables and wires. This technology standard is being developed by

the Bluetooth Special Interest Group (SIG)10. There are more than 2,000 member

companies now that support this technology. Bluetooth SIGs goal was to build up

an open specification for a low-powered, short-range, RF-based wireless

communication technology. Bluetooth allows devices to talk to each other in the

9 http://grouper.ieee.org/groups/802/15/index.html

10https://www.bluetooth.org/ .The Bluetooth SIG launched it in May 1998. It is supported by major computing and

telecommunications industry giants. Bluetooth SIG comprises of nine promoter companies including 3Com, Ericsson, IBM,Intel, Lucent Technologies, Microsoft, Motorola, Nokia and Toshiba, and thousands of member companies.Bluetooth got its name from a tenth century Scandinavian king, Harald Bluetooth, who managed to unite several unrulykingdoms. So this technology was aimed at integrating telecom and computing.


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2.4GHz unlicensed ISM band. Bluetooth technology uses low power and signals

over a relatively short distance, usually 10 meters. Bluetooth devices normally

communicate at less than 1 Mbps. The Bluetooth radio is optimized for very low

power utilization, short-range communication, and minimal interference through fast

frequency hopping. The nominal distance for a Bluetooth device with a one-milli

watt RF power output is 10 meters and this is extendable to 100 meters by raising

the power to 100 milli watts. The raw data rate for a Bluetooth device is 1Mbps.

However, the available data rate is 723 kbps. Irrespective of the brand or

manufacturer, the Bluetooth standard aims to achieve interconnectivity between any

Bluetooth devices. Any Bluetooth device in the world can connect to other

Bluetooth devices within its proximity. Bluetooth uses the ad-hoc mode and can

interact with one or more other Bluetooth devices in several different ways. The

simplest scheme is when only two devices are involved. This is referred to as a

point-to-point connection. There can be up to eight Bluetooth-enabled devices in a

piconet, with one acting as the master and the other seven as slaves [4]. A piconet

differentiates itself from the others in its neighborhood by unique frequency-hopping

sequence. Although a piconet can include no more than eight devices, attaching one

of the slaves to other piconets can extend its coverage. That is, in Bluetooth, a slave

can serve more than one master. Several of these piconets can be formed and linked

together in ad hoc fashion. This makes a scatternet with many independent and non-

synchronized piconets to make communication possible.


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Another emerging high speed personal area network standard is IEEE 802.15.3

which is based on UWB (Ultra wide broadband); it supports data rates over 400

Mbps. This is designed for delivering high speed multimedia services e.g., digital

video to be shared by many electronic devices.

2.3. WMAN (WiMAX)-IEEE802.1611

"WiMAX" stands for Worldwide Interoperability for Microwave Access. WiMAX

is a standards-based technology enabling the delivery of last mile wireless

broadband access. A group of vendors and service providers (those who founded

the WiMAX forum)12, believe that it will be widely deployed in the same way as

that of Wi-Fi. Standardization will not only reduce equipment and components costs,

allowing mass production, but it will also allow interoperability between equipments

of different vendors. The most suitable frequency band for WiMAX would be 3.5

GHz band, followed by 5.2-5.8 GHz band. It is also expected that a 2.5-2.7 GHz

band would also be a potential band for WiMAX, in some countries. The economics

of FBWA (Fixed Broadband Wireless Access) technology never made it suited for

last mile; it was also thought that it can be deployed only in areas where there is no-

preexisting infrastructure. But recent developments in WiMAX have been changing

the whole BWA industry dynamics. There are a several ways WiMAX can be

deployed. The first type of WiMAX deployment would be as the last mile, which

11http://www.ieee802.org/16

12www.WiMAXforum.org: The WiMAX Forum is an industry-led, non-profit corporation formed to promote and certify

compatibility and interoperability of broadband wireless products. Their member companies support the industry-wideacceptance of the IEEE 802.16 and ETSI HiperMAN wireless MAN standards.


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serves the residential and enterprise users as an alternative to cable and DSL. The

second type is providing backhaul for Wi-Fi hotspots and also serves as a backhaul

between conventional cellular towers. The third type is similar to metro Ethernet,

provided on point-to-multipoint sources which have direct competition with fiber.

The fourth type is the mobile version of WiMAX based on 802.16e standard, ratified

recently and is not expected to be quickly adopted by operators.

2.4. WWAN Cellular Technologies (2G/2.5G/ 3G)

The evolution of mobile wireless networks began in the 1940s. These early devices

and networks were based on the Advanced Mobile Phone Service (AMPS)

technology. In 1990s, mobile services based on digital mobile technologies formed

the second generation (2G) of wireless [11]. GSM, CDMAOne, TDMA and PDC

are based on 2G standards. GPRSrepresents the initial packet-based technology for

advancement from 2G GSM networks to 2.5G networks. GPRS data speeds are

likely to achieve data speeds of up to 171.2 Kbps.

The 3rd generation (3G) mobile technologies are established under ITU13 umbrella of

3G standards. Two competing technologies have emerged into 3G standards: one

13The ITU was established as an impartial, international organization within which governments and the private sector canwork together to coordinate the operation of telecommunication networks and services and advance the development oftelecommunications technologies. Its been working more than one hundred years to create a global communications networkwhich now integrates a huge range of technologies.


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followed the GSM path and the other the CDMA 2000. The Universal Mobile

Telephone System (UMTS) is the GSM path which uses WCDMA as the air

interface and the other follows CDMA2000 Code Division Multiple Access 2000.

3G technologies such as CDMA2000 (1xEV-DO and 3x) and W-CDMA will

theoretically offer up to 2 Mbps in a given location. But there are some significant

limitations to this theoretical capacity.

3GPP -GSM Path: All GSM Radio Access Network (RAN) specification work was

transferred to 3GPP14 in mid 2000. 3GPP was already responsible for the evolution

of the GSM core network. 3GPP formed the one global organization responsible for

RAN and core networks. 3GPP examined how to achieve a closer integration of the

two principle radio access networks: GSM/GPRS/EDGE and WCDMA radio access.

3GPP2-CDMA Path: Standardization work is being done within the 3G Partnership

Project 2 (3GPP215). Three standards have been defined by 3GPP2: cdma2000 1x,

cdma2000 1xEV-DO, and cdma2000 1xEV-DV. The cdma2001x is the first

evolution of packet data service up to 144 kbps. The second evolution, namely

cdma2000 1xEV-DO, is data only and has a packet data service up to 2.4 Mbps on

the downlink and 153 kbps on the uplink. The evolution cdma2000 1xEV-DV for

both data and voice is all IP architecture for radio access and core network with a

theoretical packet data rate up to 3 Mbps.

143GPP was formed on Technical Specifications and Technical Reports for a 3rd Generation Mobile System based on evolved

GSM core networks and the radio access technologies that they support (i.e., Universal Terrestrial Radio Access (UTRA).Then later on evolved into radio access technologies like General Packet Radio Service (GPRS) and Enhanced Data rates forGSM Evolution (EDGE)153GPP2 provides globally applicable Technical Specifications for a 3rd Generation Mobile System based on the evolvingANSI-41 core network and the relevant Radio Access technologies to be transposed by standardization bodies (OrganizationalPartners) into appropriate deliverables (e.g., standards).


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3. Comparison of Wi-Fi with other technologies

3.1 Wi-Fi vs. Bluetooth

Spectrum of operations: The main similarity between the two systems is that both

share the same unlicensed 2.4 GHz radio spectrum, which causes Bluetooth and Wi-

Fi systems to interfere with one another. The 2.4 GHz ISM radio band is going to be

the busiest radio spectrum in the world.

Range and Power: IEEE 802.11b is basically a technology intended for wireless

networking, specifically wireless local area networks (WLAN). Bluetooth utilizes

low power consumption and short range of approximately 10 meters, making it a

wireless personal area network (WPAN). IEEE 802.11b, on the other hand, has

higher energy consumption but can transmit up to 100 meters.

Transmission types: IEEE 802.11b and Bluetooth products use different

transmission types with their own features to transmit signals. Bluetooth uses FHSS

(Frequency Hopping Spread spectrum) while IEEE 802.11b uses DSSS (Direct

Sequence Spread Spectrum).

Data rate: Bluetooth does not have the data rate that a Wi-Fi can provide. IEEE

802.11b offers higher speeds than Bluetooth. 802.11b is a higher bandwidth standard

designed for large amounts of data. Although voice can be sent in compressed form

at 11 Mbps, it is not basically designed for audio application. Bluetooth has

reasonably low transmission speeds of up to 1Mbps suitable for transmitting data

files and apart from that it is ideal for voice transmission.


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Time Duration and Type of Network: Wi-Fi is used for a longer duration

connection whereas Bluetooth is optimized for peer-to-peer temporary connections.

Infrastructure based networks need an access point, which acts as a bridge to other

wireless or wired networks and has most of the functionality built in the access

point. Adhoc networks have no permanent infrastructure, and each node is very

complex. This is because every node has to implement medium access techniques

including mechanisms to handle hidden or exposed terminal problems. IEEE 802.11

is basically an infrastructure-based network. The main advantage of Bluetooth is that

it is a purely adhoc network.

3.2 Wi-Fi vs. WiMAX

Spectrum of operation: Unlike Wi-Fi, which has been deployed using primarily one

band of spectrum (2.4 GHz) and then the 5.8 GHz for 802.11a where both are

unlicensed nearly everywhere. The WiMAX standard operates between 2 to 11 GHz

of spectrum which allows for non-line-of-sight (NLOS) environments. Globally, the

WiMAX spectrum situation is more complex than Wi-Fi due to the fragmented radio

spectrum in this operating band.

Power settings:Wi-Fi systems usually transmit at the same power level all the time

as the output power is fixed. WiMAX has a separate ranging method which

calculates the right timing offset and power settings so that the transmissions from


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each client device arrive at the base station at the correct time with the same power

level.

Range and coverage:WiMAX provides a range that is broader than Wi-Fi but more

limited than wide area networks. Wi-Fi is designed typically for 100 meters. But

with high gain directional antennas or with Mesh topology, Wi-Fi coverage can be

extended. On the other hand WiMAX is designed typically for cell size of 3-6 miles

and up to 30 miles for long range. Wi-Fi is basically for indoor settings but due to

more recent to technical innovations it has been started being used in outdoor

environments.

Data Rate or Speed:WiMAX has ranges up to 30 miles and speeds up to 70 mbps.

Though the standard does not describe how much of that capacity an operator should

provide each user, a single base station could handle tens of megabits per second of

data. In a typical cell radius deployment of between 3-6 miles, WiMAX systems can

deliver data rate of up to 40 Mbps per channel, for both fixed and portable access

applications.

Media Access Control (MAC) layer: The Carrier-sense multiple access is sufficient

for Wi-Fi but a much more advanced radio access control mechanism is required for

WiMAX which is connection oriented. The WiMAX standard provides a complex

but the same (MAC) layer for all PHYs layer; single carrier and multicarrier.

Transmission type: Both802.11a/g and WiMAX are based on orthogonal frequency

division multiplexing (OFDM) and support modulations ranging from BPSK to 64

QAM. But Wi-Fi has a fixed 20-MHz bandwidth with 52 subcarriers while WiMAX

systems can use variable bandwidths from 1 to 28 MHz with 256 subcarriers (192


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data subcarriers) in both the licensed and unlicensed spectrum. The standard

WiMAX channel sizes in both unlicensed and licensed channels are 3.5, 5, 6, 7, 10

or 20 MHz channel widths.16

3.3 Wi-Fi vs. Cellular

Spectrum of operation:Cellular operates at 800, 900, 1800, 1900 and 2100 MHz all

licensed band. Cellular technologies built on 2G are basically for voice application

and later 2.5G and 3G technologies are adding data capability to it. Several service

providers are short on bandwidth for both their voice and new data subscribers. Wi-

Fi operates in the unlicensed band and is designed for high speed data service; it can

be used to extend and complement 2.5G/3G data service.

Data rate and speed: 2.5G is able to theoretically support data rates in the range of

170 Kbps kb/s, and 3G systems are able to support 2 Mbps, while Wi-Fi can support

up to 54 Mbps. More practical data rates for 2.5 G are currently in the order of 40-60

Kbps and for 3G it is up to 300 kbps. The available data rate of the cellular

technology today is not enough to provide for emerging multimedia applications.

Coverage: There is a clear tradeoff between coverage and capacity. Wi-Fi hasenough capacity compared to cellular but it has certain limitation in terms of

coverage as it is intended for a range of about 300 ft. However, coverage of cellular

networks is much wider than that of Wi-Fi networks and has a range of several km.

16 http://www.dailywireless.org/modules.php?name=News&file=article&sid=4612


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Standards and Bodies: There are two main Cellular technologies (GSM and

CDMA) and their respective migration path to 3G is via 3GPP and 3GPP2. On the

other hand, Wi-Fi has 100% global recognition and has become the single

networking standard for all developers, equipment manufacturers, service providers

and the end users. So advantage with Wi-Fi is that a large scale service-level

roaming between different WISP is possible as Wi-Fi certification has become a de-

facto standard for IEEE802.11b based products [10].

3.4 VoWi-Fi vs. VoIP

Internet telephony technology allows phone calls to be made over broadband

Internet access (both wired and wireless). VoIP allows users to make voice calls

over broadband Internet connection and Wi-Fi is for wireless broadband access.

Therefore, VoIP integration with Wi-Fi is nothing but transmitting a voice call

through a Wi-Fi internet connection. When WLAN standard was initially developed,

voice application was not the key consideration for design and deployment. The Wi-

Fi technology evolved so fast that its infrastructure demands for voice application.

Therefore, seamless roaming and quality of service become main issues and IEEE

802.11e (QoS) is designed to guarantee the quality of voice application. In the near

future more people will be using Internet telephony as we are witnessing a migration

trend from the traditional PSTN towards VoIP. As market studies indicate17, the

17 www.instat.com


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customer base is gradually growing for broadband VoIP service both in North

America and in major European countries e.g., France, Germany, Italy, Spain,

Sweden and UK. It is also estimated that more users start using Wi-Fi phones for

their residential broadband VoIP services instead of using ordinary analog phones

with an adapter. It can be inferred that a home or office Wi-Fi network forms a

convenient platform for Internet telephony using Wi-Fi enabled phones. Basically

the customers broadband wireless phones (VoWi-Fi hard or soft) become a

substitute for regular analog handset and they can start using the same phone in the

public or private Wi-Fi when they are on the move. The other main factor for

demand in VoWi-Fi is the integration of cellular and Wi-Fi networks.

4. A Wi-Fi Ecosystem

4.1 Wi-Fi with Bluetooth (WLAN / WPAN)

Bluetooth and Wi-Fi coexistence: Wi-Fi is basically a networking technology and

Bluetooth is designed for connecting peripherals to a host system. Bluetooth is used

for connecting devices like PDA's, cell phones, headphones etc, which have small

data rates. On the other hand, Wi-Fi is used to connect networks involving high data

rates. The ISM band, apart from being used by Bluetooth and Wi-Fi, is also used by

the HomeRF wireless networking system, cordless analog and digital phones,

microwave ovens, and some medical equipment. But the main source of interference

for a 802.11b networks in 2.4 GHz is Bluetooth system. The users must share the


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radio spectrum in this unlicensed radio band because no one owns any particular

frequency in this band. While WLAN technology has already been widely accepted

as a short-range wireless technology, it will be hard for Bluetooth, if the interference

problem exists. The Bluetooth SIG and Wi-Fi Alliance are working together to solve

the interference problem and coming up with different strategies to solve this. Many

companies manufacture equipment using both systems, so it is in their own interest

to solve the interference problem. The adaptive frequency hopping technique in

Bluetooth is a good first step. However this is not a long-term solution and it does

not solve a key to all interference problems. Any remedy to the interference issues

that exist between these two technologies could enhance the adoption of both.

< Figure 1>

Frequency hopping spread spectrum is a system, which divides the spectrum into

different frequencies or channels. So on a particular selected channel on a particular

time the radio selects a new channel to transmit the packet. This process is repeated

so that the message spread across the spectrum. The FHSS (Frequency hopping

Spread Spectrum) technology is good for Bluetooth communications, but it is a

severe problem for nearby by Wi-Fi communications. Since DSSS (Direct Sequence

Spread Spectrum) systems statistically occupy a given 22 MHz channel, they are

stationary within the band and do not move to avoid interference. The Wi-Fi device

has packet transmission durations that can be considerably longer than the Bluetooth

hopping interval and this leads to interference collision in the time domain. Many

other common devices such as cordless phones, microwaves, etc. use the 2.4 GHz


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two technologies are quite far from completely replacing each other, some major

cellular operators have realized the benefit of integrating these technologies. With

their high capacity and low implementation cost, some operators consider Wi-Fi the

ideal candidate for expanding the cellular data capability [7]. For example, the

mobile user can schedule high speed file transfers for downloading when they are

near a Wi-Fi hot spot. 3GPP has mentioned six inter-networking scenarios for

cellular and Wi-Fi integration [13]. Some scenarios consider offering cellular based

services within the Wi-Fi coverage. However, the seamless Wi-Fi connection

continuity from cellular network is optional. Though cellular based services may be

available in the hot spot, there might not be service continuity as the user moves

from one network to the other. There are two types of integration, tight coupling

architecture and loose coupling architecture [1, 13].

Type 1: Tight Coupling architecture: In this type of architecture the Wi-Fi is

connected to the cellular network as an alternative Radio Access Network. It is

connected to the operators core network. The hotspot can reuse the cellular

infrastructure e.g., core network resources, subscriber databases and billing systems.

The mobile users can select their network preferences or choose to get connected at

the best available network speed. This is all done by software and users are

automatically connected them to the network of their choice.


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Type 2: Loose Coupling Architecture: The hotspots are coupled with the cellular

network in the operators IP network. The Wi-Fi data traffic goes directly to the

operators IP network, instead of going via the Cellular core network. Though the

Wi-Fi and cellular networks remain separate, there is a common platform for

authentication, accounting and authorization. The hot spot may be owned by any

third party carriers with roaming enabled via a dedicated connection between the

cellular operators and Wi-Fi providers or over an existing Internet.

4.3 Wi-Fi integrated with WiMAX

Architectural overview of Wi-Fi with WiMAX: This model is considered for

incorporating WiMAX with Wi-Fi systems for two scenarios where both

technologies coexist to offer a cost effective fixed broadband internet solution. The

first type is the multi dwelling unit in a dense urban area where there are lot of

subscribers per square mile; the second market is the individual buildings and

houses where Wi-Fi /WiMAX serves as the last mile. Since WiMAX signals are

likely to fade out like a cellular service inside of buildings, the technology is actually

best when paired with interior WiFi hot spots.

Type 1: Wi-Fi / WiMAX serving Multi Dwelling Unit: In this type the majority of

SOHOs and households are in multi-dwelling units or apartment complexes.

WiMAX is used to deliver megabits of data to the apartment or office buildings; Wi-

Fi is used to distribute services to the individual houses, office rooms, lobbies,


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conference room, etc. Though the WiMAX standard does not describe how much

capacity an operator can feed each Wi-Fi access point, a single WiMAX base station

could handle hundreds of megabits per second of data and can feed Wi-Fi APs

mounted on tall buildings.

Type 2: Wi-Fi / WiMAX serving Independent houses: In the second type, individual

buildings and houses may be packed closely to each other or may be scattered. In

this case, the capital expenditure is dominated by the large number of Wi-Fi access

points needed to cover large geographic areas. The leasing cost would be much

lower, as this can use the lamppost or the rooftop of a residential building, reducing

the operating cost significantly. The coverage can be provided by the Wi-Fi APs

with high gain antennas to extend the coverage. There is a provision of using APs

with higher gain antennas to extend the coverage but still limiting the maximum

Effective Isotropic Radiated Power (EIRP) within the legal limit as described by

FCC. The normal Wi-Fi access point (802.11 b or 802.11g) only covers 300 feet

which is roughly 0.0102 square mile but for outdoors one must increase the

coverage by using higher gain antennas. It is feasible to extend the coverage further

by bearing additional cost on smart antennas.

4.4. Wi-Fi integrated with VoIP (VoWi-Fi)


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VoWi-Fi Phones (Hard & Soft): Two protocols are currently being used, namely the

H.323 and Session Initiation Protocol (SIP). At present, vendors are offering hard

phones based on both H.323 and SIP. The WISIPTM phones18 are IP

Communications devices which has SIP based VoIP communications integrated

with Wi-Fi installations. These phones can be used in any Wi-Fi network. There are

also Soft phones which can be downloaded into PDA or laptop with additional

software which turns into wireless speakerphones when connected to Wi-Fi

networks. The SIP soft phones can be downloaded into laptops, PDAs, and their

likes. The dual mode mobile phones allow the user to use the same device while in

Wi-Fi coverage and shifts to WAN (GSM or CDMA) mode when in need of cellular

coverage.

5. Service and Business Models of Integration

New products and services emerged as two or more technologies are integrated.

There is always a wide range of investment opportunities in these emerging wireless

technologies.A device could integrate Wi-Fi with Bluetooth, UWB, 2.5G, 3G, and

WiMAX or a subset of these technologies. These devices can communicate over the

best air interface and can switch between different networks without any manual

switching mode. The signal received from one network could be processed and

retransmitted over another seamlessly, depending on the application and the chosen

service model by the end user.

18 http://pulverinnovations.com/wisip.html


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Service Model of Wi-Fi with Cellular: Traditionally, cellular data networks (2.5G)

offer simple usage-based pricing of approximately $5 to $10 per megabyte. On the

other hand, Wi-Fi service has a different revenue model. There are several payment

options, such as a subscription fee on a monthly basis, a one time charge per

connection, or usage-based pricing. However, most Wi-Fi charges are based on flat

pricing with a connection fee which usually varies between 4$ to 10$ per day for a

single user at a given location. The price differential between the two services is not

only due to the infrastructure cost but also due to their capacity characteristics. If a

cellular operator invests in Wi-Fi, the Average Revenue per Hotspot (ARPH)

increases due to two sources of revenue: one from integrated service and another

from the Wi-Fi only service. The cellular data usage (like 2.5G) has been limited to

certain size of megabytes; the users have to pay extra above this limit. Therefore,

with unlimited Wi-Fi usage, users can connect at any hotspot anytime, to gain the

most value for the money they pay. If they are outside the Wi-Fi coverage, they have

to pay extra for every megabyte they exceed above the Mb limit in the 2.5G

coverage. Cellular operators have done only price bundling19

so far; if they provide

technology bundling, then they can use their Wi-Fi networks to get additional

revenue due to integration with existing data users and also offload GPRS/EDGE

traffic to the hotspots. Although the users could pay separately to use the Wi-Fi

services, the operators hope that bundled discount promotions will create more

demand for their regular service. But other kinds of revenue streams can also be

19 T-Mobile customers add a monthly $20 for unlimited Wi-Fi service to their monthly cellular bill. This is a 50% discountover the companys regular hotspot rate plans. We believe this price is low, since the subscriber has subscription to both theirWi-Fi and cellular services. But on the other hand, the subscribers, who have subscribed only to Wi-Fi, have to pay the sameamount of $40; therefore, they have an incentive to prefer the integrated service which has both GPRS and Wi-Fi, for the sameamount of money.


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added using integrated networks. The integrated users can be given an incentive

even on the connection fee, so that a heavy user may tend to browse in a hotspot

instead in a cellular coverage.

Wi-Fi integrated with cellular network provides significant advantage to the cellular

operators. The 3G systems including CDMA 1xEVDO cannot sufficiently handle

the bandwidth necessities for the future broadband applications at an affordable

price. Wi-Fi offers fast connectivity and relatively cheaper services compared to all

2.5G/3G data networks. The integration not only increases the revenue but also

improves performance of the cellular system since it reduces the traffic load in

cellular system. The operators have two choices: a) have their own Wi-Fi network

by integrating to the core network; or b) collaborate with a third party Wi-Fi

network by integrating to their IP network instead of the core network. Thus, loose

coupling architecture is not only beneficial to the cellular operator but also to third

party hot spots, because it increases revenue by increasing traffic load at their hot

spot networks. Thus, integration provides profitable business opportunities for both

the cellular operators and the new Wi-Fi startup companies. Cellular networksintegrated with Wi-Fi have some advantages over the individual Wi-Fi networks

controlled by micro carriers and aggregators. This is because cellular operators

already have an established customer base to which they can integrate Wi-Fi and

offer 3G like services with their existing 2.5G network, avoiding the cost of

deploying the expensive 3G systems. More than that, cellular operators have the

advantage of using the existing OSS (Operational Support System) and the BSS


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(Business Support System) for the deployment of the new Wi-Fi systems. With

integrated billing the operator is breaking down the barrier to people to access the

service, and experience the benefits of Wi-Fi connectivity.

Service Model of Wi-Fi with Bluetooth: Wi-Fi is a networking technology;

Bluetooth is designed for connecting peripherals to a host system. Bluetooth enabled

mobile devices can also connect to private and public networks through Bluetooth

Access Points which can support video, data and voice service. However,

Bluetooths success in the recent times has been dismissed by the evolving ubiquity

of Wi-Fi and most believe that Wi-Fi networks may make Bluetooth obsolete as a

service model due to greater market momentum for Wi-Fi. But there is still a lot of

potential for Bluetooth to complement Wi-Fi in the fact that it is already available in

more end user devices. Therefore, Bluetooth and Wi-Fi are used for different

applications; there are devices that have both technologies integrated for different

purposes.

SIM based authentication for public hotspot via Bluetooth: If Wi-Fi networks are

increasingly integrated with cellular networks, then the users will expect to have

simplified authentication20. With help of Bluetooth technology, seamless

authentication is possible between public Wi-Fi and cellular networks. The Wi-Fi

users in the public hotspot can do it via a SIM (Subscriber index module) card to

their Laptop or PDA, wirelessly through Bluetooth. The client Wi-Fi chip needs

software connected by Bluetooth to the SIM technology for cellular phones. The

client software on the device can also be used to automate the Wi-Fi hotspot login

20 www.intel.com/business/bss/ solutions/blueprints/pdf/axalto.pdf


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for users with Bluetooth enabled mobile phones. If the mobile technology initiates

an authentication, the client software can run the handshake process by using the

Bluetooth capabilities in the Laptop or PDA. This can be done by connecting to the

mobile phone SIM at the same time getting connected by Wi-Fi through the hotspot

Access Points to cellular operators core network. The client software will access

the SIM card whether it is getting attached to the Laptop or PDA, via Bluetooth in

the mobile phone. The whole process will be seamless if there is synchronization

between Wi-Fi and Bluetooth frequency operating in the same spectrum. The

integrated wireless capabilities adaptively allocate the frequencies for both Wi-Fi

and Bluetooth to work harmoniously together. Therefore, Bluetooth has the potential

to offer the most innovative solution for low to medium-speed applications in the

integrated environment.

Service Model of Wi-Fi with WiMAX: While the backbone networks are heavily

matured and more reliable with more bandwidth, the last mile to the end user is

weak [6]. At present, the operators can take leverage of the most matured

technology, e.g., Wi-Fi, to reach the end user as the last mile access; at the same

time, it can take advantage of WiMAX to minimize backhaul cost and efficiently

reduce the time for service provisioning. This is because the rental of the wired

backhaul networks accounts for a major cash outflow [2]. So to reduce backhaul cost

we can use WiMAX and to have more efficient use of the wired backhaul the

operator can also consider implementing WiMAX infrastructure mesh for backhaul

traffic. Aggregating backhaul lines into higher capacity lines is not only cheaper but


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also reduces the physical space compared to smaller speed circuits. The

disadvantage of using WiMAX as the access is that of the total estimated cost of all

WiMAX equipment sales: over half of them will be for customer premise

equipment. If properly planned and deployed, Wi-Fi with WiMAX can turn the

whole region within the geographic boundaries into what is called a hot zone.

Regardless of fixed or mobile broadband wireless, the service offered should be

affordable to all classes of the society. Wi-Fi integrated with WiMAX has not only

enough potential to compete on a cost-per-megabyte with both cable and DSL but it

can also make ubiquitous broadband a reality. If engineering and economics is

correctly applied, a Wi-Fi network can be built around an entire city with WiMAX

as a backhaul, instead of providing limited coverage at the hotspots. Cable is offered

primarily to the residential market in urban and suburban regions, while DSL is

limited to about 12,000 feet from the central office. In many parts of the world, the

wire line infrastructure does not exist, making Wi-Fi with WiMAX an attractive

technology to deliver broadband service. The city wide Wi-Fi networks can be

deployed by three main interest groups. The first, WISPs, aim to deliver high-speed

fixed and mobile voice and data services. Second, fixed line ISPs, who want to

expand their service offering by offering complementary wireless service. Third, by

municipalities and cities who want to provide emergency services to the first

responders like police, fire, and ambulance; apart from that, they can also provide

differentiated high-speed Internet services to local residents and businesses.


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The city wide Wi-Fi business case is different for each category mentioned above.

As seen in Table 9, operators can have three sources of data revenue from each type

of scenarios (Individual buildings and Multi-dwelling): one from residential users,

the second one from the SOHOs, and the third source of revenue from on demand

service (on a per connection basis). There could be a monthly subscription fee for

data subscribers which may even be 50% less than the monthly subscription fee of

cable or DSL service21

. At the same time, the service can be affordable at a lesser

rate for business users. The third type of revenue is usage based; with an average

Wi-Fi connection fee of $4-$10 (good for a day), users can transmit unlimited

volume. Considering only business travelers, there are 6 million22 visiting a big city

each year. Even if just 1%-2% of the total business visitors (per year) use pay-as

you-go service23 the operators can make significant revenue compared to the other

service model. By paying a Wi-Fi connection fee, users can connect to the network

anywhere in the city on a given day, to get the most value. Apart from this, operators

can also deploy VoIP services over Wi-Fi. With the substitute to their VoIP,

residential users can make unlimited calls, both local and long distance. In the same

way, the SOHOs VoWi-Fi service can also be offered much cheaper.

WiMAX will lower backhaul costs due to traffic aggregation and efficient use of

wired backhaul, thereby reduce operating cost. Therefore, with lower backhaul costs

and with zero dollars on CPE subsidies and truck rolls, this architecture, i.e., the

21www.chaska.net22

The Philadelphia region attracted 6.3 million business visitors to the city and the leisure travelers rose to 17.9 million in2003. http://www.centercityphila.org/docs/SOCC05_TOURISM.pdf

23 The British Library in central London, a most active and largest public Wi-Fi hotspot has an average of 1200 Wi-Ficonnections or sessions per week. The mainly indoor Wi-Fi zone allows the 3,000 visitors the library receives each day toconnect to the Internet and access e-mail using either their existing service provider or by using the Library's own pay-as-you-go service. http://www.4ni.co.uk/nationalnews.asp?id=35396 (URL accessed on May 2005)


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combination of Wi-Fi with WiMAX, seems like an attractive alternative for

broadband access.

Service/Business Model of VoWi-Fi: The advantage of using VoIP is that it allows

the transmission of voice calls over the Internet using a wired network, thereby

eliminating fees from traditional phone companies. Voice over Wi-Fi also uses the

Internet but without any physical medium. VoWi-Fi can be integrated with both

existing wired phone systems as well as the cellular systems.If inside their home or

office building, users can take advantage of the existing internet infrastructure to

perform their calls over VoWi-Fi network. In the office environment employees can

take their extensions wherever they go. VoWi-Fi will offer better coverage indoors

and higher voice quality than traditional cellular services.

Integration of VoWi-Fi for hotspot operator: The integration of VoIP in public-

access Wi-Fi hotspot could lead to a significant revenue increase for the hotspot

aggregators and so hotspot operators can make their business strategies more

lucrative by integrating VoWi-Fi with their data service. Internet telephony over

public Wi-Fi hotspots has the potential to take away considerable amount of traffic

from the cellular networks. If Internet telephony is made available in all public

hotspots there may be a serious threat to the cellular operators. The hotspot

utilization currently is very low and it has lot of capacity left unused. Therefore,

there is a huge potential for increasing hotspot usage by providing wireless Internet

telephony in the hotspot. This increase in the utilization rate due to voice services

along with data may have a significant impact on hotspots regular service model.


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Integration of VoWi-Fi for Cellular operator: By integrating VoWi-Fi with cellular

network, Wi-Fi based mobile phones are able to connect to a Wi-Fi AP or with the

cellular base station, without the use of any other hardware. This can also support

seamless transfer of calls from Wi-Fi network to the cellular network and vice versa.

The cost of making a call over the cellular network is very high when compared to

the VoWi-Fi network. This notable price difference between the two networks can

influence the way users use these networks under different circumstances. Some

users may be willing to use a VoWi-Fi network, especially for their phone calls, if

they need to talk over a long time or to perform a business call on the move.

Therefore, users have the choice of using either the cellular network with a higher

price label but with wider coverage or take advantage of VoWi-Fi services with

lower price in a limited coverage. Hybrid VoWi-Fi / Cellular phones are designed to

access public or private Wi-Fi APs, and then switch to a Cellular network

automatically when the caller has left the Wi-Fi coverage area. With adoption of

QoS and guaranteed call quality, in VoWi-Fi, Cellular operators have a choice to

offer services in broadband serviced locations with high quality at lower costs than

mobile access network. VoWi-Fi also creates other revenue opportunities for

operators by replacing fixed line phone service inside buildings. Wi-Fi phones are

not only advantageous in terms of competitive pricing of phone calls but also offer

unlimited access to text messages without any additional charges.


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Wi-Fi Technology options: The Wi-Fi chip makers are already announcing a tri-

mode chip having IEEE802.11b/g and 802.11a as their portfolio product for the near

future. Therefore, the operators planning to deploy Wi-Fi network, can strategically

place their access points to support as many technologies and standards as possible.

This allows the client software to "sniff" and select the best technology available at

any given spot. The most widely known, 802.11b, supports smaller number of audio

streams when compared to the high performing standard, e.g., 802.11a or 802.11g.

Nevertheless, 802.11a with 8 non-overlapping channels can be a technology of

choice for voice applications like VoWi-Fi, making it an attractive alternative to

802.11g which has only three non overlapping channels. The Wi-Fi services

providers can consider installing access points that include both 802.11a for voice

users and 802.11b for data users. This is a business decision; it may or may not be

economical, as profit will be determined by the amount of traffic at particular Wi-Fi

coverage locations.

6. Conclusion and Discussion

We have discussed many different technologies integrated with Wi-Fi making it the

nucleus of a wireless broadband ecosystem. With Wi-Fi proliferation increasing at

an alarming rate more care should be taken for the interference that is caused due to

the operation of other technologies at the same ISM band.Though Wi-Fi systems

are well established, coexistence between Bluetooth and Wi-Fi is the key issue in the

2.4 GHz ISM band for the success of Bluetooth. Many doubt Bluetooths future due

to the huge success of Wi-Fi in the recent years. Wi-Fi technology will dominate all


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high-speed applications. However, Bluetooth should come up with more innovative

applications and carve out a niche interoperating with Wi-Fi, 2G, 2.5G, and 3G

mobile phone networks.

For a cellular service operator, an integrated offering that combines the mobility of

cellular and the speed of Wi-Fi is a perfect mix for mobile users. In addition, by

integrating two technologies together, operators can attract new customers with

value added services provided by Wi-Fi networks, thereby hopefully, reducing the

churn. Furthermore, if Wi-Fi is integrated with existing 2.5G networks, then the

cellular operators can delay their 3G deployments as the integration could offer 3G

like services. Cellular operators can also provide a common bill to customers in the

integrated network.

Wi-Fi integrated with WiMAX has the potential to compete on a cost-per-megabyte

basis with both cable and DSL to offer a cost effective alternate broadband solution.

The position of the WiMAX technology today (in the year 2005) follows the same

footsteps as Wi-Fi technology a few years ago. The standardization and

interoperability between different vendor products made Wi-Fi prices very low and

facilitated rapid penetration from a niche to mass market. It is expected that at some

stage WiMAX will also reach a price and performance level similar to Wi-Fi. At

least for the next few years, Wi-Fi will proliferate rapidly as a last mile option and

deliver wireless broadband access at a price dramatically lower than WiMAX. Till

we find the mobile version of WiMAX, i.e., IEEE 802.16e, both technologies, i.e.,

Wi-Fi and WiMAX, should coexist, addressing different tasks.


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The integration of VoIP in a public Wi-Fi network leads to significant increase in

overall traffic and revenue at hot spots. VoWi-Fi complements both cellular and

wired phones because it provides better coverage indoors and higher voice quality

compared to conventional cellular services. Users who are not willing to pay high

prices for cellular voice service, will eventually start utilizing the VoWi-Fi network,

taking advantage of the price difference. Therefore, VoWi-Fi in a city wide

broadband environment is an alternative to wired telephone service.

In the future, as Wi-Fi services include a more diverse set of partners such as retail

chains, venue owners, aggregators, cellular operators and cities/municipalities, it

will be more appealing to integrate revenue sharing among different partners. It is

also evident that in the near future public Wi-Fi hotspots will support proximity

applications, in which Wi-Fi devices are automatically connected when they are

within the coverage.

Finally, we believe that Wi-Fi networks will eventually integrate with the Internet

and a cellular infrastructure, forming a Wi-Fi cloud around us, offering both data

and voice services.

References

[1] Ahmavaara K., Haverinen H., and Pichna R. (2003). Interworking architecture

between 3GPP and WLAN systems,IEEE Communications Magazine, vol.41,

Issue 11, November, pp. 74-81.


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[10]Henry P. S. and Luo H. (2002), Wi-Fi: Whats Next? IEEE Communications

Magazine, pp 66-72.

[11]Lehr W. and Mcknight L. (2003). Wireless Internet access: 3G vs. Wi-Fi?

Telecommunications Policy 27, pp. 351-370.

[12]Oliver S., and Poiraud P. (2002). Public WLAN for mobile operators, White

paper, Alcatel.

[13]Salkintzis A., K. Fors, C. and Pazhyannur, R. (2002) WLAN-GPRS

integration for next-generation mobile data networks, IEEE Wireless

Communications, vol.9, Issue 5, October, pp.112-124.

[14]Wanichkorn K., and Sirbu, M. (2002). The Role of Fixed wireless Access

Networks in the deployment of Broadband Services and Competition in Local.

Telecommunication Markets Telecommunications Policy Research

Conference.


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Table 1: Global Wireless Standards

Wireless Standard ETSI24

(European) IEEE25

WWAN 3GPP, EDGE(GSM) IEEE802.20 (Proposed)

WMAN ETSI HiperMAN IEEE80.16WLAN ETSI HiperLAN IEEE 802.11WPAN ETSI HiperPAN IEEE802.15 (Bluetooth)

24 www.etsi.org25 www.ieee.org


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Table 2: The IEEE 802.11family of protocols

802.11 The original WLAN Standard. Supports 1 Mbps to 2 Mbps.

802.11a High speed WLAN standard for 5 GHz band. Supports 54 Mbps.

802.11b WLAN standard for 2.4 GHz band. Supports 11 Mbps.

802.11g Establishes an additional modulation technique for 2.4 GHzband. Intended to provide speeds up to 54 Mbps.

802.11f Defines inter-access point communications to facilitate multiplevendor-distributed WLAN networks.

802.11e Address quality of service requirements for all IEEE WLAN

radio interfaces.

802.11h Defines the spectrum management of the 5 GHz band for use inEurope and in Asia Pacific.

802.11i Address the current security weaknesses for both authenticationand encryption protocols. The standard encompasses 802.1X,TKIP, and AES protocols.

802.11k Radio resource management

802.11n Enhancements for higher throughput up to 200+ Mbps

802.11r For fast roaming and address maintaining user connectivity fromone access point to another.

802.11s Deals with mesh networking


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Table 3: Wi-Fi Throughput by IEEE Standard

IEEE Standards 802.11a 802.11b 802.11g

Supported Data rate 54, 48, 36, 24,18, 12, 9, 6

Mbps

11, 5.5, 2, 1 Mbps 54, 48, 36, 24, 18,12, 9, 6, 11, 5.5, 2,

1 MbpsSpectrum 5.8 GHz 2.4 GHz 2.4 GHzModulation OFDM CCK OFDM & CCKStandard Ratified 1999 1999 2003Non Overlapping

Channels 8 Channels 3 Channels 3 Channels


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Table 4: The WiMAX Standard

Fixed Outdoor(Pre-WiMAX)

IEEE 802.16 a

Fixed IndoorWiMAX(2005)

IEEE 802.16 d

Full nomadicWiMAX(2006)

IEEE 802.16 e

Frequency

5.8,2.5,3.5 GHzFrequency

2.5, 3.5 GHZFrequency

5.8, 2.5, 3.5 GHz

Applications

Backhaul for Wi-Fi hotspots

Indoor access and for fixedInternet applications

Broadband access,Anywhere, Anytime.Integrate WiMAX inchips along with Wi-Fi


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Table 5: Cellular Technologies(2G/2.5G/3G)

2G 2.5G 3G28 65Kbps 56 144 Kbps 384 2000 KbpsTDMA GPRS EDGEGSM GPRS WCDMAPDC WCDMACDMA CDMA2000 CDMA2000 1xEV


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Table 6: Wi-Fi vs. Bluetooth

Wi-Fi Bluetooth

Spectrum 2.4 GHz & 5.8 GHz 2.4 GHzData rate Up to 54 Mbps 1 MbpsRange 100 meters 10 metersPower Medium LowTransmission Type DSSS & OFDM FHSSPrimary devices Laptops, Printers and

other networking devicesCellular phones, headsets,other small powereddevices

Standard Body WECA Bluetooth SIG

The main similarity between Wi-Fi and Bluetooth is that both uses unlicensed spectrum in 2.4 GHz

band. Wi-Fi is basically a networking technology and Bluetooth is designed for connecting

peripherals to a host system.


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Table 7: Wi-Fi vs. WiMAX

Characteristic Wi-Fi WiMAX

Spectrum Unlicensed2.4 GHz and 5.8 GHz Both Licensed andUnlicensed spectrum 2-11GHz

Coverage Designed for 300 ft rangefor indoor use.

Due to recent innovationsCoverage are beingextended using Meshtechnique or high gaindirectional antennas for

outdoor usage.

Designed for 10 KmsMaximum range up to 30miles.

Basically designed foroutdoor environments(terrains, buildings, Treesetc)

Capacity 54 Mbps in 20 MHzchannel

75 Mbps to 100 Mbps(Based on Modulationtechnique )

Channel width 20 MHz (Fixed channelsize)

3 MHz -20 MHz (FlexibleChannel size )

Quality of Service VoWi-Fi is emerging and802.11e is working on theQoS issues to get ratified

Standard has inbuilt QoSfor voice and multimediaapplications

WiMAX provides a range that is broader than Wi-Fi but more limited than wide area networks. Wi-Fi

is designed typically for 100 meters but a recent innovation has made it an alternate access

technology for last mile access.


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Table 8: Wi-Fi vs. Cellular

Wi-Fi Cellular (2.5G , 3G)

License Unlicensed Licensed

Spectrum 2.4 GHz and 5.8 GHz 800, 900, 1800, 1900, 2100MHz

Coverage Several km 300 ft for indoor usageCan be extended up to 1 mile

Data rate and Speed 802.11b -11Mbps802.11a/g-54 Mbps

2.5G- 170 Kbps3G- 300Kbps

These two technologies complement one another in terms of capacity and coverage. Wi-Fi operates

in the unlicensed band and is designed for high speed data service; it can be used to extend and

complement 2.5G/3G data service with good coverage.


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Table 9: Hotspot Service (SWOT Analysis)

Strength Weakness

Excess capacity.

IEEE802.11a ,b or g (Technology

Options).

IEEE 802.11n is working on the

advancement of the PHY layer to

increase the data rate up to 100

Mbps.

Global roaming (Standardized).

Easy to deploy.

Wi-Fi ,one of the fastest growing

technology in Wireless Industry. Target Business users.

Pricing of Wi-Fi is very cheap

compared to Cellular service.

Lack of Mobility (Poor handoff)

Poor coverage (Difficult to cover a

wider area)

No fast roaming (IEEE 802.11r is

working on this issue)

Power consumption.

Interference due to unlicensed band.

More competition due to less entry

barriers. Wi-Fi Industry fragmented.(Needs

Aggregation and consolidation). Lot of device operating in the ISM

band. (ex. Microwave, cordless,..)

Opportunity Threat

Internet telephony over hotspot

Wi-Fi hard phones can replace old

analog home phones.

Soft phones are very cheap and can

be downloaded into any computing

devices.

Provides platform for future value

added service in venues.

Coverage can be improved by

having roaming agreements.

VoWi-Fi technology can compete

with cellular technology.

Existing 2.5G(GPRS,1xRTT)

Launch of 3G(UMTS ,CDMA EVDO)

Aggressive 3G marketing

Cellular providers can leverage

existing customer base.

Backed by big players and already

invested billions of dollars in 3G

spectrum.

Wi-Fi service model is complementary to cellular voice and data service. The main strength and

opportunity with Wi-Fi service model is that a large scale service-level roaming between different

WISP is possible as Wi-Fi certification has become a de-facto standard for IEEE802.11 based

products.[10]


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Figure 1: The spectrum occupancy of different technologies in 2.4 GHz.


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Time Time

Frequenc

y

FHSS DSSS

Figure 2: FHSS (Bluetooth) and DSSS (IEEE 802.11b).


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Figure 3: Architecture of GPRS integrated with Wi-Fi networks: Tight

coupling


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Figure 4: Architecture of GPRS integrated with Wi-Fi networks: Loose

Coupling


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Figure 5: Wi-Fi / WiMAX serving MultiDwelling Unit

WiMAX is used to deliver megabits of data to the apartment or office buildings; Wi-Fi is used to

distribute services to the individual houses, office rooms, lobbies, conference room, etc.


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Figure 6: Wi-Fi / WiMAX serving Independent houses / SOHOs

In this type, individual buildings and houses may be packed closely to each other or may be

scattered. The leasing cost would be much lower, as this can use the lamppost or the rooftop of a

residential building, reducing the operating cost significantly. The coverage can be provided by the

Wi-Fi APs with high gain antennas to extend the coverage.

Towards a Wi-Fi Ecosystem

Documents