Cdma Ppt 575c10

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ë The advent of Cellular communications began in 1940s known as MTS(Mobile Telephone Systems) ë There has been a gradual advancement in the capacity and signal strength. ë The development can be broadly divided into 3 categories namely first, second and third generations.

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1.FDMA(Frequency Division Multiple Access) 2.TDMA(Time Division Multiple Access) 3.CDMA(Code Division Multiple Access)

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" ë ith FDMA, frequencies are separated in the frequency domain, each is allotted a different set of frequencies to operate upon. ë Subscribers are assigned a pair of voice channels (forward and reverse) for the duration of the call. è

" un this system, each is allocated a different time slot. Forward link frequency and reverse link frequency is the same. A synchronous switch is responsible for the time switching.

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" D There is no restriction on time and frequency in this scheme. D All the s can transmit at all times and at all frequencies. D Because s are isolated by code, they can share the same carrier frequency, eliminating the frequency reuse problem encountered in other technologies. D ith CDMA, unlike other cellular telephone standards, subscriber data change in real time, depending on voice activity and requirements of the network and other s of the network.

ë A comparative study between the above three access technologies with respect to time and frequency is as shown below.

! # | ë un this method, the direct sequence(input data) which is spread over a limited bandwidth is multiplied with a code or spreading sequence (a pseudorandom sequence also known as PN sequence). ë This will spread the input data over the entire bandwidth of the communication channel. ë The power density is also reduced and is spread over the frequency spectrum and hence is known as spread spectrum method.

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| á $ D The modulated signal is transmitted over the channel and all s can receive it but only the which knows the correct code can decode the message.

á | %& ë un 1984 Qualcomm unc. proposed a cellular telephone system and standard based on spread spectrum technology which marked the advent of CDMA. ë Since then the evolution has been rapid as shown: ë uS-95 A ( 1995) ë uS-95B ë uS-95A as air-interface standard and uS-41 in core network; the complete network known as |dmaOne. ë CDMA 2000 1x ë CDMA 2000 1x ʹEV-DO ʹ data only 2.4 Mbps + RF backward compatible.

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' ë ( : The location of the transceivers are called base stations. A base station serves as central control for all the s within the cell. ë ) : Such as automobiles and pedestrians carrying the mobile. ë ) %': The mobile units and the base station communicate directly with the MTSO. ë An MTSO controls channel assignment, call processing, call setup, and call termination which include signaling, switching, supervision and allocating r.f. channel.

| $%& ë ) * ë Mobile subscribers access the CDMA2000 1x data network using a mobile station, such as a mobile phone, modem, a laptop with an embedded CDMA2000 chip, a broadband access wireless router, or PC Card on a laptop computer. ë The mobile station interacts with the access network (AN) to obtain radio resources in order to exchange data packets. The mobile station, in tethered mode, can also act as a modem for a computer. ë The mobile station automatically s with the network upon power-up, and upon successful registration, it is ready for voice and data calls.



$%& ë There are two types of access networks: 1xRTT and 1xEVDO. ë The AN is the mobile station͛s entry point into the mobile network . ë Maintains the communications link between the mobile station and the core network. ë The AN is composed of the following elements: ë ( ë ut is physically composed of antennas and towers. ë The BTS manages radio resources including radio channel assignment and transmit and receive power management and acts as the interface to mobile stations. ë &| º ë ut maintains the ͞connection state͟ between the access network and mobile stations. ë †$%&|

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ë These schedule packet transmission on the air interface and manage handoffs between BTS`s .

|$%& ë The core network acts as the gateway between the access network and the unternet or enterprise private networks. ë ut provides authentication, authorization, and ing (AAA) services, provides access to network services, uP mobility, and manages uP addresses. ë The core network comprises the following elements: ë $+º'' ë The PDSN is the gateway between the access network and the core network. ë +' ë The AAA and the home agent (HA) are used for authentication, authorization, and ing for data services. The AAA/HA stores and records usage and access information for billing and invoicing purposes.

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º† † $.|$$á ʹ For initial system acquisition & to uniquely identify cell / sectors . Every sector of every cell site has a unique pilot channel. - Subscriber unit with network information related to cell site identification, pilot transmit power & cell site PN offset. '' ʹ Used by base station to page the subs unit call set-up and traffic channel assignment information. | # The

/ , the voice and control information between the subs unit & base station.

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| #Provides communication from

Mobile to base station when mobile is not using traffic Channel. ë # The traffic channel carries the actual call traffic in reverse channel also. ë un CDMA 2000 1x , in addition to above channels, Fwd. Quick paging channel ,Fwd. Supplemental channel , Rev. pilot channel , Rev. supplement channels are available.

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Frequency of operation: 824-849Mhz & 869-894 Mhz Duplexing Method : Frequency Division Duplexing Access Channel per carrier: Maximum 61 Channels RF Spacing: 1.25 Mhz verage: - 5 Km with hand held telephones and approx. 20 Km with fixed units.

ë CDMA channel in the trans and receive direction is a FDD (Frequency Division Duplexing) channel. ë Frequency-division duplexing means that the transmitter and receiver operates at different carrier frequencies.

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| á|†0 As wireless data networks become increasingly prevalent, new possibilities and challenges continue to emerge. Security becomes key to delivering solutions that meet today͛s demand for mobility. Some of today͛s top security issues and concerns are: Unauthorized systems and network access Auditability and compliance Customer data breaches unternal and external sabotage

| á|†0(á$Ạë The key inherent security benefits of CDMA technology can be summarized as: ë CDMA codes inherently spread the signals across the full channel bandwidth of 1.25 MHz. ë Soft handoff (multiple cells simultaneously ing the call) typical for the CDMA operation make it very difficult to ͞follow͟ the CDMA cellular call. ë Long code mask (LCM) provides ͞built-in͟ security at the physical layer. ë CDMA signals are very difficult to intercept. ë CDMA attacks require sophisticated and expensive equipment. ë Access is only provided to authenticated mobile stations/subscribers.

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á†|á$| Voice: un the form of calls made. SMS: ut allows subscribers to send and receive short text messages between mobile stations . MMS: ut allows for the transmission of images, audio, video, and rich text using AP (wireless application protocol) technology and an MMScapable mobile station. Pocket data ( 144 kbps / 2.4 Mbps ) ʹNuC & EVDO cards. Prepaid and Postpaid Services VPN(Virtual Private Network) Bank ATM / Branch ATM connectivity

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'| | ë : The customer is charged for usage in the prior month (hence 'post' usage), and hence does not feature any limitations on volume of service used. ë : ut asks customers to add a certain amount to their s prior to usage and their maximum usage is limited to the amount that is added to the . ë | is a series of activities designed to enhance the level of customer satisfaction ʹ that is, the feeling that a product or service has met the customer expectation. ë Many organizations have implemented loops that allow them to capture at the point of experience. ë The operators provide the with one dial customer care services and supplement them by having offices in cities.

| |†á 1 ë ! -CDMA uses code division multiple access whereas GSM uses time division multiple access. ë %| 2| ë #CDMA has been traditionally faster than GSM, though both technologies continue to rapidly leapfrog along this path. Both boast "3G" standards, or 3rd generation technologies. ë ) ) †

|$|$ ë un the age of growing connectivity CDMA plays a crucial role in bringing us closer. ë According to a survey CDMA networks over 270 million subscribers worldwide. ë The techniques involved in it enable us to achieve the data transfer speeds of almost 3.1 mbps(EVDV cards). ë Future advancement in technology is going to take us to new heights in of capacities and facilities offered to customers.