CDMA

CDMA stands for Code Division Multiple Access

CDMA is a wireless technology used in transmission of signal from places with high Security and noise reduction.

The principle of Spread Spectrum is used to work with CDMA.

Spread signal is below the noise level noise and has no effect on the signal.

CDMA does not frequency specific to each user. Instead, every channel uses the full available spectrum.

Individual conversations are encoded with a pseudo-random digital sequence.

CDMA always provides better capacity for voice and data communications

CDMA is a common platform for 3G technologies

Analog radio transmission technologies like Advanced Mobile Phone System were used in CDMA at the time of its inception

A unique code is received by all mobile network users and is allowed continuous network access instead of intermittent and timed access.

EVDO stands for Evolution Data Optimized

EVDO is a 3G broadband technology used by Verizon, Spring, Alltel

It provides typical download speeds of 600 to 1400 KBPS

A personal broadband service for wide range of customers

It is always On

EVDO utilizes CDMA signals

Users can be connected remotely for using email, downloading large files, spreadsheets etc.

EVDO is relatively low cost with high capacity

Allows rich web browsing and application usage

Seamless roaming, internal internet connectivity without relying on other’s connection, accessibility to the corporate Virtual Private Network by customers are some of the advantages over WiFi .

HSPA is a combination of 2 mobile telephony protocols – High Speed Downlink Packet Access and High Speed Uplink Packet Access

HSPA improves the performance of existing WCDMA protocols.

HSPA provide increased performance by utilizing schemes of modulation and refining the protocols, through which the base stations and handsets communicate

HSPA is used for better usage of the available bandwidth provided by WCDMA

HSPA supports data rates of up to 14 MBit / s in the downlink

HSPA supports data rates of up to 5.8 MBit / s in the uplink

HSPA reduces the latency and increases up to 5 times more system capacity during downlink and twice more system capacity during uplink

HSPA uses 16QAM for yielding higher bit rates

HSPA rollouts are achieved by implementing software upgrades to existing 3G networks. This gives HSPA a head start over WiMax.

CDMA

Same frequency is used by every user and simultaneous transmission occurs

Every narrowband signal is multiplied by wideband spreading signal, usually known as codeword

Every user has a separate pseudo-codeword, i.e., orthogonal to others

Only the desired codeword is detected by the receivers and others appear as noise

It is mandatory for the receivers to know about the transmitter’s codeword

FDMA

When the channel is not in use, it sits simply idle

Bandwidth of Channel is relatively narrow (30 KHz), known as narrowband system

Little or no equalization is needed for spreading symbol time

Analog links are suitable for FDMA

Framing or synchronization bits are not needed for continuous transmission

Tight filtering is needed to minimize interference

Combined with FDD for duplexing

CDMA

Power limited system

While people talking, random noise band playing occurs

Conversation need to be extracted from the background din

GP is high when people speak different languages, which is easier to distinguish individual speakers

It is difficult for distinguishing individuals, when GP is low.

The system performance will be degraded for every user when the number of users increases.

Fading would be reduced with wide frequency spectrum

Need to have separate multipath signals with different delays by “chip” unit.

TDMA

Receiving or transmission is allowed for only one user in a given slot

All slots are assigned cyclically

The transmission is non-continuous

It is essential to use digital data and modulation

Data rate overhead is between 20% – 30%

Overhead tradeoffs are size of data payload and latency

Multiple users are shared with single carrier frequency

Handoff is made simpler by using non-continuous transmission

All slots are assigned on demand

Due to reduced inter user interference, the power control is less stringent

Data Transfer Speed:

CDMA is faster than GSM.

CDMA2000 downstream rate is 2 megabits / second, through EVDO, where GSM downstream rate is up to 384 kilobits / second, through EDGE technology

Subscriber Identity Module (SIM) cards:

SIM is tied to the network, rather than the actual phone. Phones with card-enabled can be used with any carrier of GSM

Proprietary handsets are linked to one carrier only and not card-enabled in CDMA

Roaming:

GSM carriers have wider coverage of more rural areas, where as CDMA may not cover rural areas compared to GSM carriers

International Roaming:

GSM has facility to offer more international roaming, as the number of connections in world market dominate GSM network.

CDMA phones do not have the capacity; however, there are more countries that use CDMA networks.

The Differences:

CDMA is one of the types of mobile connections for making calls where as GPRS is a technology for internet connections through a mobile phone.

GPRS enables to surf the internet from a mobile phone. GPRS technology is used in other gadgets apart from mobile phones.

W-CDMA technology is faster than GPRS, since the user cares about the technology that is applied for air interface.

Average latency on GPRS is around 1.3 seconds, where as on CDMA is around 400 milli second

GPRS supports only User Datagram Protocol, where as CDMA supports both UDP and TCP

GPRS relies on Network Address Translation and a private IP address is assigned to it. On the other hand CDMA assigns a public IP address CDMA is better because:

E-mail is pretty light, until you enter MS-Office.

Pocket PC’s support for office documents with similar functionality which can be had on Palm OS and Symbian

Upon availability of APIs, a software developer could write various applications, like voice transfer, data transfer to client’s account, integrating billing amount etc.

Web services could be utilized .