Cellular Technology Overview
Before we begin to focus on the wireless data it is important to understand the types of cellular technology the cellular carriers offer. In the United States, there are two competing standards for cellular data. The first is called CDMA and was developed by Qualcomm and is more prevalent in the United States. The second is called GSM. GSM is more of a worldwide standard and is offered in the United States as well. Below is a list of the carriers in the United States and the technology that they employ for their networks.
Cellular vs. PCS
PCS is often used interchangeably with cellular when discussing wireless service. Primarily this happens when discussing voice service. Personal Communications Services (PCS) is similar to cellular phone service, but with an emphasis on personal service and extended mobility. True PCS means that other services like paging, caller ID and e-mail are bundled into the service. The lines have become grey over the past several years due to the mergers and acquisitions of several national cellular carriers with PCS providers.
Transmission Frequencies
- PCS devices use frequencies bands between 1.85 and 1.99 GHz (1850-MHz to 1990-MHz).
- Cellular devices in the United States operate in the 824-MHz to 894-MHz frequency bands;
Note: Europe and Asia use the 900 MHz and 1800 MHz bands.
Multiple-mode vs. Multiple-band
- Multiple band - A phone that has multiple-band capability can switch operating frequencies automatically between the cellular and PCS bands.
- Multiple mode – The term “mode” refers to the type of transmission technology being used. Multiple mode devices are less important with the carriers retiring support for analog cellular (AMPS) service. Multi-mode devices have the capability of switching automatically between digital and analog service areas.
You may have a Multi-mode/Multi-band device. In fact you may hear the term quad band describing a lot of GSM devices. This means that the device works with all four frequency bands. This means you can travel seamlessly from the US to Europe or Asia and still have support for the device. Of course you need appropriate support for accounts from the providers but technically it would work. One thing to remember is that you can’t cross between CDMA and GSM technologies.
2G, 3G and 4G technologies
You may have heard the terms 2G, 3G or 4G and that 3G or 4G is better (or faster). This refers to the generation of wireless that a carrier is offering. There currently are 3 generations of wireless commonly referred to as 1G, 2G, 3G and 4G. Occasionally some vendors will refer to intermediate increases in performance as 2.5G. In the M2M world, faster isn’t always necessary unless you are dealing with applications that require faster connections such as video surveillance. Faster connections typically cost more, as you would expect.
* Speed refers to the kilobits per second (k)
Abbreviations, “buzzwords” and services
The carriers have chosen abbreviations like 1xRTT, EvDO, GPRS, EDGE, HSDPA, UMTS, WiMax and LTE) to make it easy to refer to the type of data services they offer.
As if it isn’t complicated enough by now, each carrier has made their own decisions regarding what data services they offer. Just as each carrier has it’s own CDMA implementation, (i.e.: Sprint/Verizon) each carrier also has it’s own implementation of data services.
Coverage
As in real-estate, Location, Location, Location is important. More appropriately Coverage is important in the wireless world. The coverage for data is different than the coverage for voice. For example the ability of Verizon and Sprint users to use EvDO and the availability of HSPA from AT&T and T-Mobile are based on where the carriers have implemented it. Contact your carrier and review their coverage maps to decide whether they offer the data service you need were you need to use it. Working with a good solutions partner or integrator can help greatly to ease the burden of choosing the right carrier and service.
Additionally it is important to understand that coverage is that data connections are affected by more than just having a signal. Data services like GMS, EDGE and 1xRTT all share frequency channels with voice calls. So if a tower is choked with voice calls then you won’t get the full throughput of the data connection. Data services are secondary and the network will adjust speeds accordingly. Also, if you are in a fringe coverage area, you may be able to connect to data services however you may experience intermittent drop outs of data coverage and delays in downloading content.
Hopefully this helps clear up the understanding of the wireless data world. Be sure to use the forums to get answers to your specific needs and applications.
Related Posts
- M2M Wireless Networks – Short Range Solutions
- Part 2: M2M cellular devices: What are they and who are the players?
- Distributed Antenna Systems (DAS) and Why the Growth?
- M2M cellular devices: What are they and who are the players?
- In Building Cellular and PCS Coverage for Healthcare
Tags: Cellular, communications, Distributed Antenna Systems, Wireless
