PART-A (2 MARKS)

1. Distinguish between 1G & 2G cellular network?

In Ist Generation cellular network, all the communications are done by amplitude modulation

technique and 2G under Frequency Modulation technique. 1St

generation technique doesn’t have

any packet transmission whereas 2nd

generation has GPRS etc.

2. Define location management and handoff management?

It is defined as management which includes the location of mobile station and how the call has

been transferred from one base station to another base station which is nothing hand off

technique.

3. What is link transfer?

It is nothing but the link which is established from the BS to MS, due to some conditions this link

will completely surrender to some other node point. That is from one Base station to another Base

station. This is called as link transfer.

4. How mobile station gets authorized by AUC?

Mobile station’s IMEI Number and MIN identification number will be sent the AUC. That is

carried over by Home location register. After the verification IMEI and MIN, Mobile station gets

authorized by AUC by sending an ACK to the near by base station.

5. State the different GSM mobility management

GSM Mobility management is done purely by the Service provider. It is nothing but managing

the mobility of GSM (Global system for Mobile). It offers SMS, internet etc.

6. What is Network signaling?

Network signaling is nothing but signals which are associated with the network with the mobile

station. So that MS can communicate with the MSC and BSC

7. What is WML?

WML stands for wireless mark up language. It is majorly used in the Mobile internet. The

purpose of WNL is using internet in the mobile phone itself.

8. State the salient features of Wireless application protocol?

WAP allows the mobile phone to use internet

It works under less memory, less CPU etc.

Consumes low power

Allow the user to download various multimedia files.

9. How many co channels interfere is present in the first tier for a cluster size of 7

Six no. of co channels can be used in the present in the first tier for a cluster size of 7.

10. What is near-far effect in wireless network?

When used with FM or spread spectrum modulation, it is possible for the strongest user to

successfully capture the intended receiver, even when many users are also transmitting. If the

closest transmitter is able to capture a receiver because of small propagation path loss, it is called

as near -far effect in wireless network

PART-B (11 MARKS)

11. Draw the block diagram of a Trunking & GOS in detail?

Trunking techniques are used throughout the world and are particularly popular in the

U.S. South America, Australia, and China. The exact frequency allocations for AMPS differ

from country to country. Nevertheless, the air interface standard remains identical throughout the

world. Like all other first generation, analog, cellular systems, AMPS use frequency modulation

(FM) for radio transmission. In the United States, transmissions from mobiles to base stations

(reverse link) use frequencies between 824 MHz and 849 MHz, while base stations transmit to

mobiles (forward link) using frequencies between 869 MHz and 894 MHz.. For AMPS, the

maximum deviation of the FM modulator is 112 kHz .The control channel transmissions and

blank-and- burst data streams are transmitted at 10 kbps for AMPS.

AMPS cellular radio systems generally have tall towers which support several receiving

antennas and have transmitting antennas which typically radiate a few hundred watts of effective

radiated power. Each base station typically has one control channel transmitter (that broadcasts

on the forward control channel), one control channel receiver (that listens on the reverse control

channel for any cellular phone switching to set—up a call), and eight or more FM duplex voice

channels. Commercial base stations support as many as fifty-seven voice channels.

The actual number of control and voice channels used at a particular base station varies

widely in different system installations depending on traffiic, maturity of the system, and

locations of other base stations. The number of base stations in a service area varies widely, as

well,from as few as one cellular tower in a rural area to several hundred or more bases tations in

a large city

Each base station in the AMPS system continuously transmits digital FSK data on the

forward control channel (FCC) at all times so that idle cellular subscriber units can lock onto the

strongest FCC wherever they are. All subscribers must be locked, or ―camped" onto a FCC in

order to originate or receive calls. The base station reverse control channel (RCC) receiver

constantly monitors transmissions from cellular subscribers that are locked onto the matching

FCC. In the U.S. AMPS system, there are twenty-one control channels for each of the two

service providers in each market, and these control channels are standardized throughout the

country.

AMPS facts

Analog FM modulation

RF bandwidth 30 kHz. The band can accommodate 832 duplex channels, among which

21 are reserved for call setup, and the rest for voice communication.

Frequency allocated by FCC on 824-849 MHz for downlink and 869-894 MHz for uplink

traffic.

Uses the same system throughout the US

Available in U.S., Canada, Hong Kong, New Zealand, Thailand

A narrowband versus exists with a 10 kHz channel spacing, such that 2496 channels can

be assigned, in stead of 832 for the normal AMPS mode.

N-AMPS

To increase capacity in large AMPS markets, Motorola developed an AMPSlike system

called N-AMPS (narrowband AMPS) [EIA91]. N-AMPS provides three users in a 30 kHz

AMPS channel by using FDMA and 10 kHz channels, and provides three times the capacity of

AMPS. By replacing AMPS channels with three N-AMPS channels at one time, service

providers are able to provide more trunked radio channels (and thus a much better grade of

service) at base stations in heavily populated areas. N -AMPS uses the SAT and ST signaling

and blank-and-burst functions in exactly the same manner as AMPS, except the signaling is done

by using subaudible data streams. Since 10 kHz channels are used, the FM deviation is

decreased. This in turn, reduces the S / (N + I ) which degrades the audio quality with respect to

AMPS. To counteract this, N-AMPS uses voice companding to provide a ―synthetic‖ voice

channel quieting.

N-AMPS specifies a 300 Hz high pass audio filter for each voice channel so that

supervisory and signaling data may be sent without blanking the voice, The SAT and ST

signaling is sent using a continuous 200 bps NRZ data stream that is FSK modulated, SAT and

ST are called DSAT and DST in N-AMPS because they are sent digitally and repetitiously in

small, predefined code blocks. The voice channel signaling is done with 100 bps Manchester

encoded FSK data and is sent in place of DSAT when traffic must be passed on the voice

channel. As with AMPS wideband signaling, there are many messages that may be passed

between the base station and subscriber unit, and these are transmitted in N-AMPS using the

same BCH codes as in AMPS with a predefined format of 40 bit blocks on the FV C and 48 bit

blocks on the RVC.

Global System for Mobile (GSM)

Global System for Mobile (GSM) is the second generation cellular system standard that

was developed to solve the fragmentation problems of the first cellular systems in Europe. GSM

is the world`s First cellular system to specify digital modulation and network level architectures

and services. Before GSM,European countries used different cellular standards throughout the

continent,and it was not possible for a customer to use a single subscriber unit throughout

Europe. GSM was originally developed to serve as the pan-European cellular service and

promised a wide range of network services through the use of ISDN. GSM’s success has

exceeded the expectations of virtually everyone, and it is now the world’s most popular standard

for new cellular radio and personal communication systems.

12. Define and explain the importance of the Low tier PCS method?

PACS — Personal Access Communication Systems

PACS is a third generation Personal Communications System originally developed and

proposed by Bellcore in 1992. PACS able to support voice, data, and video images for indoor

and microcell use. PACS is designed to provide coverage within a 500 meter range. The main

objective of PACS is to integrate all forms of wireless local loop communications into one

system with full telephone features, in order to provide wireless connectivity for local exchange

carriers (LECS).

PACS System Architecture PACS was developed as a universal wireless access system for wide spread applications in

private and public telephone systems which operate in either licensed or unlicensed PCS bands.

PACS may be connected to a PBX or Centrex, and may be served by a Central Office in

residential applications The PACS architecture consists of four main components: the

subscriberunit (SU) which may be fixed or portable, the radio ports (RP) which are connected to

the radio port control unit (RPCU), and the access manager (AM), as shown in Figure .Interface

A, the air interface, provides a connection between the SU and RR Interface P provides the

protocols required to connect.

PACS Radio Interface

The PACS system is designed for operation in the U.S. PCS band. A large number of RF

channels may be frequency division multiplexed with 80 MHz separation, or time division

multiplexed. PACS and WACS channel bandwidth is 300 kHz . WACS originally used TDMA

with frequency division duplexing (FDD), with eight time slots provided in a 2.0 ms frame on

each radio channel. When used with FDD, the reverse link time slot is offset from its paired

forward link time slot by exactly one time slot plus 62.5 ps. The forward link covers 1850

MHzto 1910 MHz and the reverse covers 1930 MHz to 1990 MHz.

Modulation -— PACS uses rr/4—DQPSK modulation. The RF signal is shaped using a raised

cosine rolloff shaping filter (rolloff factor of 0.5) such that 99% of the transmitted signal power

is contained within a channel bandwidth of 288 kHz. Eight time slots, each containing 120 bits,

are sent in a 2.5 ms frame.

Personal Handyphone System (PHS)

The Personal Handyphone System (PHS) is a Japanese air interface standard developed by the

Research and Development Center for Radio Systems (RCR). The PHS network interface was

specified by the Telecommunications Technical Committee of Japan The PHS standard, like

DECT and PACS-UB, uses TDMA and TDD. Four duplex data channels are provided on each

radio channel. rc/4 DQPSK modulation at a channel rate of 384 kbps is used on both forward

and reverse links. Each TDMA frame is 5 ms in duration, and 32 kbps ADPCM is used in

conjunction with CRC error detection (without correction).PHS supports seventy-seven radio

channels, each 300 kHz wide, in the 1895 MHz to 1918.1 MHz band. Forty channels in the

1906.1 MHz to 1918.1 MHz are designated for public systems, and the other thirty-seven

channels are used for home or oiiice use in the 1895 MHz to 1906.1 MHz band.PHS uses

dynamic channel assignment, so base stations are able to allocate channels based on the RF

(interference) signal strength seen at both the base and portable. PHS uses dedicated control

channels (unlike DECT) which all subscribers lock to while idle. Handoffs are supported only at

walking speeds, as PHS is designed for microcell/indoor.

13. Write brief notes about PACS network signaling

PACS Network signaling is a third generation Personal Communications System

originally developed and proposed by Bellcore in 1992. PACS able to support voice, data, and

video images for indoor and microcell use. PACS is designed to provide coverage within a 500

meter range. The main objective of PACS is to integrate all forms of wireless local loop

communications into one system with full telephone features, in order to provide wireless

connectivity for local exchange carriers (LECS).

PACS was developed as a universal wireless access system for wide spread applications

in private and public telephone systems which operate in either licensed or unlicensed PCS

bands. PACS may be connected to a PBX or Centrex, and may be served by a Central Office in

residential applications The PACS architecture consists of four main components: the subscriber

unit (SU) which may be fixed or portable, the radio ports (RP) which are connected to the radio

port control unit (RPCU), and the access manager (AM), as shown in Figure .Interface A, the air

interface, provides a connection between the SU and RR Interface P provides the protocols

required to connect.

The PACS system is designed for operation in the U.S. PCS band. A large number of RF

channels may be frequency division multiplexed with 80 MHz separation, or time division

multiplexed. PACS and WACS channel bandwidth is 300 kHz . WACS originally used TDMA

with frequency division duplexing (FDD), with eight time slots provided in a 2.0 ms frame on

each radio channel. When used with FDD, the reverse link time slot is offset from its paired

forward link time slot by exactly one time slot plus 62.5 ps. The forward link covers 1850

MHzto 1910 MHz and the reverse covers 1930 MHz to 1990 MHz.

Modulation -— PACS uses rr/4—DQPSK modulation. The RF signal is shaped using a raised

cosine rolloff shaping filter (rolloff factor of 0.5) such that 99% of the transmitted signal power

is contained within a channel bandwidth of 288 kHz. Eight time slots, each containing 120 bits,

are sent in a 2.5 ms frame.

The Personal Handyphone System (PHS) is a Japanese air interface standard developed

by the Research and Development Center for Radio Systems (RCR). The PHS network interface

was specified by the Telecommunications Technical Committee of Japan The PHS standard,

like DECT and PACS-UB, uses TDMA and TDD. Four duplex data channels are provided on

each radio channel. rc/4 DQPSK modulation at a channel rate of 384 kbps is used on both

forward and reverse links. Each TDMA frame is 5 ms in duration, and 32 kbps ADPCM is used

in conjunction with CRC error detection (without correction).PHS supports seventy-seven radio

channels, each 300 kHz wide, in the 1895 MHz to 1918.1 MHz band. Forty channels in the

1906.1 MHz to 1918.1 MHz are designated for public systems, and the other thirty-seven

channels are used for home or oiiice use in the 1895 MHz to 1906.1 MHz band.PHS uses

dynamic channel assignment, so base stations are able to allocate channels based on the RF

(interference) signal strength seen at both the base and portable. PHS uses dedicated control

channels (unlike DECT) which all subscribers lock to while idle. Handoffs are supported only at

walking speeds, as PHS is designed for microcell/indoor.

14. Explain briefly about the IS-41 network signaling in detail?

IS-41 Network signaling contains the frequency reuse terminologies:

Frequency reuse was implemented by restructuring the mobile telephone system

architecture into the cellular concept. The concept of frequency reuse is based on assigning to

each cell a group of radio channels used within a small geographic area. Cells are assigned a

group of channels that is completely different from neighboring cells. The coverage area of cells

is called the footprint. This footprint is limited by a boundary so that the same group of channels

can be used in different cells that are far enough away from each other so that their frequencies

do not interfere.

Cells with the same number have the same set of frequencies. Here, because the number of

available frequencies is 7, the frequency reuse factor is 1/7. That is, each cell is using 1/7 of

available cellular channels.

Principles of cellular frequency reuse

In the cellular concept, frequencies allocated to the service are re-used in a regular pattern of

areas, called 'cells', each covered by one base station. In mobile-telephone nets these cells are

usually hexagonal. In radio broadcasting, a similar concept has been developed based on

rhombic cells.

To ensure that the mutual interference between users remains below a harmful level, adjacent

cells use different frequencies. In fact, a set of C different frequencies {f1, ..., fC} are used for

each cluster of C adjacent cells. Cluster patterns and the corresponding frequencies are re-used in

a regular pattern over the entire service area.

Frequency reuse plan for C = 3, with hexagonal cells.

(i=1, j =1) Frequency reuse plan for C = 7 (i=2, j

=1).

The total bandwidth for the system is C times the bandwidth occupied by a single cell.

Reuse Distance

The closest distance between the centres of two cells using the same

frequency (in different clusters) is determined by the choice of the

cluster size C and the lay-out of the cell cluster. This distance is

called the frequency 're-use' distance. It can be shown that the reuse

distance ru, normalised to the size of each hexagon, is

ru = SQRT{3 C}

For hexagonal cells, i.e., with 'honeycomb' cell lay-outs commonly used in mobile radio,

possible cluster sizes are C = i2 + ij + j

2, with integer i and j (C = 1, 3, 4, 7, 9, ...). Integers i and j

determine the relative location of co-channel cells.

7-cell reuse with i = 2 and j =1.

15. Explain the VOIP service for mobile networks?

Voice over Internet Protocol (VoIP)

VoIP is a technology that allows for the transmission of voice communications over the

internet. This technology has been implemented to transmit voice calls between fixed-line

telephones and the benefit for travelers is that VoIP enables communication from a computer to

VoIP land lines, other computers and VoIP enabled mobile phones.

A user accesses the internet and downloads a VoIP software program onto the computer. Some

VoIP software programs are free whilst some require a subscription fee. The user can then

initiate a conversation with particular users who have a compatible VoIP capability enabled on

their phone line, mobile or computer. Next, the user speaks into a microphone connected to the

computer. The VoIP program then converts the sound into a digital signal and transmits it via the

internet to the recipient’s device. The recipient’s VoIP device then converts the digital signal

back into sound and conveys the voice to the listener. The quality and speed of VoIP calls are

virtually the same and sometimes better than other voice services. Vodafone Australia’s

submission to the inquiry stated that many areas frequented by travelers such as airports, hotels

and cafes have wireless internet access and thus VoIP communication is a viable substitute.13

The submission to the inquiry by AMTA further supports the notion that a wide range of internet

resources are available to travelers and that VoIP provides an almost perfect alternative to

international mobile roaming.14

The AMTA submission further notes that a range of mobile devices are emerging which can

access the internet and run VoIP programs, thus increasing the applicability of VoIP

communication as a substitute to international roaming.15 However the Committee notes that

accessing the internet from these mobile devices whilst overseas would presumably incur

international data roaming charges which may in turn make the use of VoIP on mobile devices

significantly less cost effective.

The Committee notes that some of the limitation’s outlined in the ACCC’s review apply to the

use of VoIP. Namely, VoIP services (with exception of VoIP on mobile devices) do not provide

the mobility or ease of contact as do international mobile roaming voice services.16

16. Explain the operation of GSM SMS?

SMS (Short Message Service) is the transmission of short text messages to and from a

mobile phone, or any other device capable of generating the SMS. It is composed of a

maximum of 160 characters, each coded on 7 bits (GSM) or 140 bytes.

End to end SMS delivery completes in two parts, First SMS submission in SMSC (Short

Message Service Centre) by originating subscriber, second Delivery of SMS to recipient

subscriber. So SMS is a Stored and Forward Service.

Once a message is sent, it is received by a Short Message Service Centre (SMSC) of the

calling subscriber’s network, which then delivers it to the appropriate destination device.

In the GSM SMS delivery, SMS termination does not require the SMSC of the recipient

subscriber’s Operator. However In CDMA (Code Division Multiple Access) network or

GSM to CDMA SMS transfer, or in case of some services like Push SMS, the recipient

SMSC is also used for terminating the SMS to the recipient. In all these types of SMS

transfer, the air interface-signalling channel is extensively used for terminating the SMS

traffic.

SMS uses the signaling channel (not dedicated), so it can be sent/received simultaneously

with the voice/data/fax service over a network.

SMS Text Length:

The ―short‖ part refers to the maximum size of the text messages: 160 characters (letters,

numbers or symbols in the Latin alphabet). For other alphabets, such as Chinese, the maximum

SMS size is 70 characters.

Types of SMS :

With the growing convergence Technology of networks and services, SMS can be send from a

mobile phone, fixed phone, or even via the Internet. On the basis of originating and terminating

identities, SMS can be broadly classified into the following 4 categories : P2P, A2P, P2N & I2P.

P2P (Person to Person) : In Person to Person (P2P) mode, the SMS is between two

individual subscribers. The SMSC or originating operator stores the SMS & sends it to

the recipient, either directly or in case of GSM to CDMA or CDMA to CDMA network,

through the SMSC of the terminating operator.

A2P (Application/Advertiser to Person) : In Advertiser/Application to Person (A2P)

SMS mode, advertising agencies have a commercial agreement with one or more service

providers. Advertisers provide the messages and mobile numbers to an operator, who

then sends the messages in broadcast mode to the recipients. If the SMS transfer is on-

net, then SMS moves only within the network of one operator and hence there is no issue

of loading resources of other operators, but if the recipient subscriber is attached with

another operator, then the resources of the terminating operator are also used for

delivering of such SMSs. This type of SMS delivery is also termed as Push method.

P2N (Person to Network) or P2A (Person to Application) : The Person to Network

(P2N) SMSs are usually an on-net service. In this type mode, the content provider usually

has a revenue share agreement with the service provider. The operator gives the content

provider a 4-5 digit short SMS code. The content provider then uses the short codes to

provide different kinds of services like astrology information, ring tones, picture

downloads, tele-voting, games, etc. Operators charge premium rate for these SMS to the

short codes.

I2P (Internet to Person) : The Internet to Person (I2P) arrangement allowed by some

operators with the provision of a web interface enables a person to send an SMS from the

Internet to mobile subscribers. They also accept SMS originating from the Internet

messaging web sites.

Basic SMS Network Element :

SMSC

HLR

MSC

VLR

BSC

BTS

UE (User Equipment : Mobile/Laptop/Fixed Phone)

SMS is carried on a signaling channel of air interface from mobile handsets to the Base

Transceiver Station (BTS), and thereafter it is carried on the Signaling System 7 (SS7) signalling

channel throughout BSC, MSC/VLR, SMSC.

Basic SMS Call Flow :

End to end SMS transaction completes in 2 parts :

Message submission by originating subscriber to its SMSC (Mobile Originating Part)

Message delivery by SMSC to recipient Subscriber (Mobile terminating Part)

Basic end to end SMS call flow shown in following diagram :

SMS Originating Part – MO SM Submit :

The SM is sent from the originating Mobile Station (MS) to the serving Mobile

Switching Center (MSC). The address of the SMSC where the SM should be submitted to

is stored on the SIM card of the subscriber and forwarded to the MSC with the message.

The MSC forwards the SM to the SMSC. The SMSC returns a positive (ACK) or

negative (NACK) response indicating whether the message was successfully stored of

not.

SMS Terminating Part – MT SM Deliver :

To delivers a SM SMSC has to find out the location (serving MSC) and the International

Mobile Subscriber Identity (IMSI) of the recipient subscriber first. This information

(routing information) is retrieved from the Home Location Register (HLR) of the

recipient subscriber based on the recipient number (MSISDN).

HLR Provides routing Information to SMSC, which includes IMSI and serving MSC of

recipient number.

Based on routing information SMSC delivers SM to the serving MSC and MSC forwards

it to the recipient Mobile Station.

SMS Delivery Report :

Successful Delivery – On successful delivery SMSC sends delivery report to the originator if

requested.

Failed Delivery – If SMS is not delivered to the recipient number SMSC send failure reason to

the originator.

Permanent Error : For example – Unknown Subscriber

Temporary Error : For example – Absent Subscriber

SMSC Retry : In case of temporary errors the SMSC schedules a next delivery attempt, called

SMSC retry.

Network Trigger : If the subscriber is not reachable (absent) the SMSC notifies the HLR that

there is a message waiting for the recipient number. When the HLR detects the presence of the

subscriber, it alerts the SMSC and SMSC forwards SM to the serving MSC.

Regular SMS Messages :

Send Routing Information for Short Message (SRI-SM):

Between Origin SMSC and Destination HLR, to retrieve the routing information needed for

routing the short message to the servicing MSC.

Mobile Originating Forward Short Message (MO Forward SM):

Between Origin MSC and Origin SMSC, to forward mobile originated short messages.

Mobile Terminating Forward Short Message (MT Forward SM):

Between Origin SMSC and Destination MSC, to forward mobile terminated short messages.

Send-Info-For-MO-SMS:

Between the Origin MSC and VLR, to request subscriber related information from the VLR.

Send-Info-For-MT-SMS:

Between the Destination MSC and VLR, to request subscriber related information from the

VLR.

Report Short Message Delivery Status:

Between Origin SMSC and Destination HLR, to set the Message Waiting Data into the HLR or

to inform the HLR of successful SM transfer after polling.

Alert Service Centre:

Between Destination HLR and Origin SMSC, to inform SMSC that a subscriber, whose

MSISDN is in the Message Waiting Data file, is active or the MS has memory available.

Inform Service Centre:

Between Destination HLR and Origin SMSC, to inform the SMSC which MSISDN number is

stored in the Message Waiting Data file, or to provide status on different messaging flags.

Ready For Short Message:

Between the Destination MSC and Destination VLR as well as between the Destination VLR

and the Destination HLR. The MSC initiates this service if a subscriber indicates memory

available situation. The VLR uses the service to indicate this to the HLR.

SMS Applications :

Text message exchange between Mobile subscriber.

Ring Tone

Logo

Stock Information

Tele-Voting (TV Show)

Vending machine Remote Management

17. Study the operation of UAProf and caching concepts of WAP

Existing markup languages and content written in those markup languages presume that

devices have similar display sizes, memory capacities, and software capabilities. Content is also

largely oblivious to the available network bandwidth and perceived network latency. As WAP-

enabled devices come of age, this homogeneity assumption is no longer universally valid. In

particular, mobile devices can be expected to have an an ever-divergent range of input and output

capabilities, network connectivity, and levels of scripting language support. Moreover, users may

have content presentation preferences that also cannot be transferred to the server for

consideration. As a result of this device heterogeneity and the limited ability of users to convey

their content presentation preferences to the server, clients may receive content that they cannot

store, that they cannot display, that violates the desires of the user, or that takes too long to

convey over the network to the client device. Recently, work has begun within the World-Wide

Web Consortium (W3C) to define mechanisms for describing and transmitting information about

the capabilities of Web clients and the display preferences of Web users. The Composite

Capabilities/Preferences Profile (CC/PP) defines a high-level structured framework for describing

this information using the Resource Description Framework (RDF) [RDF]. CC/PP profiles are

structured into named ―components,‖ each containing a collection of attribute-value pairs, or

properties. Each component may optionally provide a default description block containing either a

set of default values for attributes of that component or a URI that refers to a document containing

those default alues. Any attributes explicitly provided in the component description therefore

override the default values provided in the default description block or through that URI. The

CC/PP specification does not mandate a particular set of components or attributes, choosing

instead to defer that definition to other standards bodies. The CC/PP Exchange Protocol over

HTTP [CC/PPex] enables CC/PP profiles to be transported over the HTTP 1.1 protocol [HTTP]

with the HTTP Extension Framework [HTTPex]. This protocol enables effective profile caching

at Web servers and proxies.

The User Agent Profile (UAProf) specification extends WAP 1.1 to enable the end-to-end flow

of a User Agent Profile (UAProf), also referred to as Capability and Preference Information

(CPI), between the WAP client, the intermediate network points, and the origin server. It seeks to

interoperate seamlessly with the emerging standards for Composite Capability/Preference Profile

(CC/PP) [CCPP,CCPPex] distribution over the Internet. It uses the CC/PP model to define a

robust, extensible framework for describing and transmitting CPI about the client, user, and

network that will be processing the content contained in a WSP response. The specification

defines a set of components and attributes that WAP-enabled devices may convey within the

CPI.1 This CPI may include, but is not limited to, hardware characteristics (screen size, color

capabilities, image capabilities, manufacturer, etc.), software characteristics (operating system

vendor and version, support for MExE, list of audio and video encoders, etc.), application/user

preferences (browser manufacturer and version, markup languages and versions supported,

scripting languages supported, etc.), WAP characteristics (WML script libraries, WAP version,

WML deck size, etc.), and network characteristics (bearer characteristics such as latency and

reliability, etc.). This specification seeks to minimize wireless bandwidth consumption by using

a binary encoding for the CPI and by supporting efficient transmission and caching over WSP in

a manner that allows easy interoperability with the CC/PP Exchange Protocol over HTTP.

As a request travels over the network from the client device to the origin server, each network

element may optionally add additional profile information to the transmitted CPI. These

additions may provide information available solely to that particular network element.

Alternatively, this information may override the capabilities exposed by the client, particularly in

cases where that network element is capable of performing in-band content transformations to

meet the capability requirements of the requesting client device.

Origin servers, gateways, and proxies can use the CPI to ensure that the user receives content

that is particularly tailored for the environment in which it will be presented. Moreover, this

specification permits the origin server to select and deliver services that are appropriate to the

capabilities of the requesting client. Finally, it is expected that this specification will be used to

enhance content personalization based on user preferences, and other factors, as enabled by the

Platform for Privacy Preferences Project (P3P) [P3P].

The user agent profile is concerned with capturing classes of device preference information.

These classes include (but are not restricted to) the hardware and software characteristics of the

device as well as information about the network to which the device is connected. The user agent

profile contains information used for content formatting purposes.

A user agent profile is distinct from a user preference profile that would contain application-

specific information about the user for content selection purposes. For example, a user

preference profile might designate whether the user is interested in receiving sports scores and, if

so, the particular teams. The specification of user preference profiles is beyond the scope of this

document.

In accordance with the CC/PP note [CCPP], the user agent profile schema is defined using an

RDF schema and vocabulary [RDF]. This document defines the structure of this schema in terms

of the class definitions and semantics of attributes for devices adhering to the WAP standard.

Extensibilty guidelines are also offered to assist in extending the schema with new components.

The information contained within the profile is provided on behalf of the user who will

be receiving the content contained in the associated WSP response.

The CC/PP repository storing the profile is secure, meaning that it does not permit

unauthorized modification to stored profile information. The functionality associated with

this repository may be implemented in a WAP gateway or intermediate proxy or as a

separate standalone element in the network.

WSP/HTTP headers are generally not encrypted. Because this specification does not

define any security mechanisms, care will be taken when including user-confidential

information2 in the profile unless the profile is transmitted over an end-to-end secure

channel (e.g. WTLS to the origin server).

An implicit chain of trust exists between the client and origin server. The integrity of the

profile is maintained (in other words, not compromised) as it is transmitted through or

cached within the network. It is assumed that the network elements that contribute

property descriptions to the profile are trusted. Network elements will not assemble a

"history" about users by tracking the deltas in their profile over time.

To ensure the integritiy of the profile, lower-level mechanisms, such as WTLS, must be

used.

o Use of the profile by the origin server is intended to enhance the user’s

experience. Therefore, should the profile be discarded, be corrupted, or be

otherwise inaccessible, then the origin server will still provide and deliver content

to the client in a best-efforts fashion.

o This specification builds upon and coexists with numerous WAP and Internet

standards. These relationships are summarized below:

Composite Capability/Preferences Profiles (CC/PP) [CC/PP]: This specification defines

the CPI structure according to the structure mandated by the CC/PP specification note.

Resource Description Framework (RDF) [RDF]: The CC/PP specification uses the RDF

syntax to represent the CPI. In designing or extending the schema, a schema designer

must be familiar with the RDF concepts.

Wireless Session Protocol (WSP) [WSP]: CPI is transmitted over wireless networks

within WSP headers.

WAP Binary XML (WBXML) [WBXML]: When the CPI is transmitted over the WSP

protocol, this specification mandates that it be encoded according to the WBXML

specification.

CC/PP Exchange Protocol over HTTP [CC/PPex]: When transmitted over the Internet,

this specification requires that the CPI be transmitted using the CC/PP Exchange Protocol

over HTTP which, in turn, defines headers in HTTP 1.1 [HTTP] with the HTTP

Extension Framework [HTTPex].

WAP Push Access Protocol (PAP) [WAP-PAP]: This protocol is used by push origin

servers to retrieve the CPI from the WAP gateway or Push Protocol Proxy (PPG). The

request is issued over HTTP, and the response contains the profile, with MIME type

text/xml.

This section describes the end-to-end architecture within which this specification

operates. It is informative.

The end-to-end system consists of five logical components:

A client device capable of requesting and rendering WAP content.

A wireless network employing WAP 1.1 or later protocols.

A WAP-capable gateway capable of translating WAP protocol requests into

corresponding requests over the Internet and translating responses from the Internet

into corresponding responses over the WAP protocols.

The Internet or an intranet using TCP/IP-based protocols and possibly having one or

more protocol gateways and Web/HTTP proxies.

An origin (Web) server that can generate requested content.

Though this specification refers to five end-to-end system components, actual

configurations may physically deploy those components in many forms. For example,

the latter three components (WAP gateway, Internet/intranet, and origin server) might

easily be merged into a single server-side system connected to the WAP network.

Moreover, the WAP gateway may itself be distributed, with different hosts serving as

endpoints for different layers of the WAP protocol stack.

19. Explain the Mobile station execution environment

Mobile Station Application Execution Environment is a framework to ensure a predictable

environment for third-party applications in GSM or UMTS handsets. MExE does this by

defining different technology requirements called "classmarks." MExE classmark 1 is based on

WAP, classmark 2 on PersonalJava and JavaPhone, and classmark 3 on J2ME CLDC and MIDP.

Other classmarks may be defined in the future. MExE specifies additional requirements for all

classmarks, for instance a security environment, capability and content negotiation, a user

profile, user interface personalization, management of services and virtual home environment. A

handset can support multiple classmarks.

The aim of Mobile Station Application Execution Environment (MExE) is to provide

a comprehensive and standardised environment on mobile phones for executing

operator or service provider specific applications. MExE is designed as a full

application execution environment on the mobile terminal. It builds a Java

Virtual Machine into the client mobile phone. MExE is designed to be used to provide

sophisticated intelligent customer menus and also facilitate Intelligent Network (and so-called

GSM CAMEL) services. MExE plans to integrate mobile phone location services and already

supports a wide range of man-machine interfaces such as voice recognition, icons and soft keys.

MExE shares several similarities with the Wireless Application Protocol, in that both protocols

have been designed to work with a range of GSM mobile network

services from SMS to GPRS and later with UMTS. Whereas WAP incorporates some

scripting, graphics, animation and text, MExE allows full application

programming. This necessitates the need for MExE to include a strict security

framework to prevent unauthorised remote access to the user's data.

Because programming and running Java applications requires significant

processing resources on the mobile client, MExE is primarily aimed at the next

generation of powerful smart phones. On the other hand, MExE terminals can also

include today?s regular phones, because MExE incorporates a capability

indication method called classmarks. MExE classmarks define the MExE-related

services that a particular terminal supports. There will be classmarks that

match and those that exceed WAP functionality.

The MExE mobile client can inform

the MExE server of its classmark and therefore its capabilities.

Development of the initial MExE protocols is being carried out in SMG4; the

European Telecoms Standards Institute (ETSI), the GSM standards setting body.

Supporters of this work include Motorola, Nokia, Lucent Technologies and Nortel

(with the concept Nortel Orbitor smart phone in line with the MExE concept).

MExE will be available further in the future than Wireless Application Protocol

(WAP) because the processing power to run the Java applications is not currently

available in mobile terminals. It is also worth noting that whilst MExE is a

only a GSM and Universal Mobile Telephone System (UMTS) standard, WAP is being

designed for all cellular standards including Code Division Multiple Access

(CDMA)."

20. What are the concepts of WLL?

Wireless Local Loop (WLL) is a technology that connects subscribers to the public switched

telephone network (PSTN) using radio signals to substitute the copper wires.

The WLL sustem includes cordless access systems, proprietary fixed radio access, and fixed

cellular systems. Sometimes WLL is called radio in the loop (RITL) or fixed-radio access (FRA).

The bandwidth using WLL is much higher than that possible in the copper loop. Wireless

local loop is a practical and economical last mile (or first mile) solution for connecting

subscribers in areas that do not have the wired infrastructure such as remote rural area and some

developing countries.

The WLL system is based on a full-duplex radio network that provides local telephone-like

service among a group of users. The WLL unit consists of a radio transceiver and the WLL

interface assembled in one metal box. Two cables and a telephone connector are the only outlets

from the box; one cable connects to a directional antenna and a phone receptacle to connect to a

common telephone set. A fax or modem could also be connected for fax or computer

communication. WLL systems incorporating various types of wireless technologies as

summarized as follows:

1. TDM/TDMA and P-MP communications equipment:

The system uses communications equipment based on time division multiplex/time division

access (TDM/TDMA) technology and a point-to-multipoint (P-MP) system provides service

coverage over a wide area encompassing the base station, relay stations and subscriber stations.

2. Fixed use of cellular systems:

This approach uses the wireless equipment of a cellular phone system, thereby curtailing the

mobile function. Using cellular phones as the subscriber terminals makes it possible to hold

down the system cost.

3. PHS-WLL system:

The system uses PHS terminal technology and wireless equipment. Since the voice encoding

system uses 32 kbps adaptive differential pulse code modulation (ADPCM), speech quality on a

par with that of fixed telephony is obtained.

WLL: Wireless Local Loop