2009 5 Nov

Windows Mobile Modem – Cdma Usb Modems

CDMA stands for Code Division Multiple Access Cdma Usb Modem, a cellular technology that competes with GSM technology for dominance in the cellular world. Originally, it was developed by the Qualcomm and later on was enhanced by Ericsson. CDMA phones are characterised by high capacity small cell radius, employing spread-spectrum technology and a special coding scheme. In short, we can say that CDMA is a form of spread spectrum signaling.

For CDMA implementations there are many terms used. The original that was defined by the Qualcomm was known as IS-95. Later on, it was revised by the IS-2000 standard (CDMA 2000). All the major communication companies round the globe such as Nokia, Samsung, LG, Motorola Etc., utilize this cellular network of CDMA. The added advantage of CDMA phones is that it can be used as a USB Modem on Mac OS X.

Now a days there are different and exciting variations in CDMA phones. We now have cdma2000 and its variants like 1X EV, 1XEV-DO, and MC 3X. They refer to variants of usage of a 1.25 MHz channel. 3X uses a 5 MHz channel.

More and more added facilities and additions have been introduced such as:

Sprint has launched Mobile Movies on CDMA Phones

Live ABC TV News Programming over US Smart Phones

China Unicom has launched Dual Mode GSM CDMA Phones

Ericsson gets MTN South Africa 3G CDMA contract

QUALCOMM tests Assisted-GPS over CDMA

Lucent to support CDMA at 450 MHz

Nokia to Supply WCDMA 3G Network Expansion to MTC

CDMA 1xECDMA 1xEV-DO deployments grow

CDMA Phones include very accurate time signals (usually referenced to a GPS receiver in the cell base station), so cell phone CDMA-based clocks are an increasingly popular type of radio clock for use in computer networks. The main advantage of using CDMA cell phone signals for reference clock purposes is that they work better inside buildings, thus often eliminating the need to mount a GPS antenna outside a building.

CDMA Phones have the facility of international roaming globally. With this facility, you can expect your phones to work everywhere with all services. Regional, National or International roaming have several elements that are required in order for CDMA roaming to be facilitated, such as CDMA roaming business elements, technical elements, service features, roaming service providers, inter-carrier implementation and roaming carrier maintenance.

CDMA phones have certain important features like the narrowband message signal multiplied by wideband spreading signal or pseudonoise code and each user has its own pseudonoise code or (PN) number.

What features and functionality should you understand in order to fully take advantage of accessing the internet via a mobile phone? Although this can appear complicated and involved … a little information goes a long way to “keep it simple”.

For the sake of discussion …. let’s say you have a mobile handset with the following specifications:

Networks…

2G Network-GSM 900/1800/1900
3G Network-UMTS 2100

Data…

GPRS- Clause 10(4+1/3+2 slots),32-48 Kbps
3G-384 Kbps

You have configured the software application given with the phone on your laptop …. and once you connect the phone to the laptop using the USB connection you can access Internet. The settings used in the software application includes “call type=GPRS”. The connection speed (downlink) is around 375 Kbps when checked through a freely available tool on the Internet …. and the phone’s modem speed is shown as 460.8 Kbps all the time( on the network connection). Since your speed is less than 384 Kbps (3G speed is given as the phone’s spec), you’re likely using 3G. Since GPRS is also supported, when the 3G coverage is not available, you’re probably able switch to GSM/GPRS.

Your service provider says they support EDGE,GPRS,3G and HSDPA/HSUPA.

Here’s some questions you may ask …..

* What are the theoretical maximum speeds of EDGE,GPRS, 3G?

* What is actually meant by 3G here?

* What is the underlaying technology used by my phone?

* Which method is better to connect the phone to the laptop; Bluetooth or USB?

* Your phone spec says Bluetooth v1.2 and USB2.0 and you’ve heard that USB2.0 (480Mbps) is faster than Blootooth v1.2 (1 Mbps). Is this correct? Will it make any difference, since your connection from phone to the Internet is 375 Kbps?

Here’s some feedback to help you work through such a scenario …. and the associated questions above:

For sure, the speed with USB 2.0 should be much better than that through Bluetooth (of any class).

3G is a network technology that should offer some extended data services in addition to the regular GSM features. However, I would recommend that you check with your service providers since they should have the exact specifications that you asked for.

Theoretical speeds for EDGE are up to 10 times those of GPRS. But again, since these depend on network configuration you need to check with the service provider.

Since your speed is less than 1 mb/s, frankly, it doesn’t matter if you use bluetooth or USB – the speeds cited are correct. I would use what is most convenient for you.

In any case, the edge/hsdpa connection speeds are still slower than either Bluetooth or USB, so they will not bottleneck your speed. So as long as your battery isn’t about to run out, you can connect however you choose to.

3G HSUPA is Third Generation High-Speed Uplink Packet Access – a 3G mobile telephony protocol, which offers increased data transfer speeds and capacity of up to 3.6 Mbps on the downlink and up to 1 Mbps on the uplink, under ideal conditions.

3G HSDPA 3.6 is a 3G High-Speed Downlink Packet Access mobile telephony protocol, which offers increased data transfer speeds and capacity of up to 3.6 Mbps on the downlink and up to 348Kbps on the uplink, under ideal conditions.

3G – Third Generation High-Speed Downlink Packet Access – offers increased data transfer speeds and ables customers to access the Internet and email from their cellphones.capacity of up to 1.8 Mbps on the downlink and up to 348Kbps on the uplink

EDGE (Enhanced Data rates for GSM Evolution) or EGPRS provides data transfer rates significantly faster than GPRS or HSCSD. EDGE increases the speed of each timeslot to 48 kbps and allows the use of up to 8 timeslots, giving a maximum data transfer rate of 384 kbps.

HSCSD (High Speed Circuit Switched Data) enables data to be transferred more rapidly than the standard GSM (Circuit Switched Data) system by using multiple channels. The maximum number of timeslots that can be used is four, giving a maximum data transfer rate of 57.6 kbps (or 38.4 kbps on a GSM 900 network). HSCSD is more expensive to use than GPRS, because all four slots are used simultaneously – it does not transmit data in packets. Because of this, HSCSD is not as popular as GPRS and is being replaced by EDGE.

GPRS – General Packet Radio Service is a mobile data service available to customers with GSM cellphones. With a GPRS connection, the phone is “always on” and can transfer data immediately, and at higher speeds: typically 32 – 48 kbps. An additional benefit is that data can be transferred at the same time as making a voice call.

I would recommend using USB as it is faster then Bluetooth. You will not have a bottleneck created by the bluetooth link.

Regarding the underlying technology …

When you phone is connected to a 3G network it will be using W-CDMA (Wideband Code Division Multiple Access) W-CDMA is the higher speed transmission protocol as used in the UMTS system, it is a third generation follow-on to the 2G GSM networks Cdma Usb Modem deployed worldwide.

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