Chapter 6

Types Of Boosters: choices and matching to your needs and cellular provider

Overview- boosters are radio frequency amplifiers and as such they are dependant on the signal that is input to them to be of use. Cellular handsets and base stations transmit many types of modulated signal (analog, CDMA, TDMA, etc.) and the handsets transmit these signals at different power levels depending on the type of system they are designed for. For example: A CDMA phone has maximum transmit power of about 250 milliwatts and transmit a signal is known as “spread spectrum”. A very powerful amplifier is required to amplify it without destroying the signal in the process of amplifying it, a GSM phone on the other hand can transmit 2 watts but its signal is not as difficult to amplify. Added to these differences are also the different frequencies that are used in cellular.

Because of all of the differences boosters must be made to match the phone, the system and the frequency that they are to amplify if they are going to be beneficial. There are several boosters available on the market that are advertised as “dual-band one size fits all” devices. It is impossible for these devices to perform their advertised capabilities and purchasing or using one for a period of time will show their limitations.

Booster Choices:

Iden- this category includes Nextel, Southern Linc and Mike. This system and the handsets for this system use only one frequency and the same digital standard. The choice is only one, an Iden booster.

GSM 1900 (PCS)- this category includes service providers T-Mobile and Fido and all GSM1900 only capable handsets from providers like Cingular, AT&T and others. They only use one frequency and one digital standard. The choice is only one, a GSM1900 booster.

Dual Band CDMA- this category is more complicated than the two above and requires some consideration before a choice of booster is made. Most CDMA handsets are capable of digital PCS band, digital Cellular band and analog communication.

CDMA coverage is normally deployed in major cities using the PCS (1900 Mhz band) and cities are normally covered with large numbers of towers and repeaters and coverage is usually very good. Because of the large numbers of towers and their close proximity to handsets, towers (which control the transmit power of the handset) rarely command a handset to transmit at maximum power, therefore using a PCS 1900 Mhz booster in this case would be of no benefit because the network would command the handset to power down to the level that is acceptable to the tower, however, if you have a Sprint phone that you have set to “home only” and use this phone only in the PCS band, then a PCS 1900 Mhz booster for CDMA phones is your only and logical choice.

CDMA coverage in non-urban areas is usually in the Cellular (800 Mhz band) and this is where towers are spaced at greater distances from each other and also the frequency band in which analog operates. This is the band where spotty coverage exists and using a Cellular 800 Mhz booster is advisable. A dual band CDMA phone with Analog capability used with a Cellular 800 Mhz booster will get coverage in as many places as possible and have the best coverage of any CDMA phone/booster combination.

Dual Band TDMA- this category is the same as the dual band CDMA. TDMA coverage is normally deployed in major cities using the PCS (1900 Mhz band) and cities are normally covered with large numbers of towers and repeaters and coverage is usually very good. Because of the large numbers of towers and their close proximity to handsets, towers (which control the transmit power of the handset) rarely command a handset to transmit at maximum power, therefore using a PCS 1900 Mhz booster in this case would be of no use and the network would command the handset to power down and since PCS only TDMA phones do not exist, a Cellular Band 800 Mhz TDMA booster that will improve coverage for both digital and analog in rural areas is the only choice.

Dual Band GSM- GSM coverage is normally deployed in major cities using both the 800 Mhz cellular band and the PCS (1900 Mhz band) and cities are normally covered with large numbers of towers and repeaters and coverage is usually very good. Dual bnad operators urban networks use a method called "channel hopping". The phones are constantly to hop channels and frequencies, giving priority to the 1900 Mhz fequency band primarily and the 800 Mhz channels when 1900 Mhz is low, in other words, GSM networks back down to 800 Mhz when signal is not good enough in 1900 Mhz and if a call fails it will fail at this frequency. Even so, because of the large numbers of urban towers and their close proximity to handsets, towers (which control the transmit power of the handset) rarely command a handset to transmit at maximum power, and the need for a booster or external antenna in this environment is rarely required. GSM networks in rural areas are almost always in the 800 Mhz band and this is where most weak signals are found. A Cellular Band BST850 booster that will improve coverage in rural areas is recommended for Dual band GSM handsets. It will also reduce urban area call drops that are normally associated with unsuccessful "channel hop"

Special Note for Dual Band GSM as of March 2004- this category is the one that requires the most consideration if you travel by land to many geographic and remote areas. GSM systems are relatively new to the North American cellular scene and as such there are problems and deficiencies with both the networks and handsets. These problems are being worked out and will be eventually fixed throughout the land but for now one must carefully consider his or her choices. Most of the GSM service providers are existing TDMA providers that have both digital TDMA and analog systems in place and full use with very comprehensive voice coverage all over the land, however, TDMA data transfer speeds are not fast enough to compete with CDMA networks therefore GSM is being added to the existing TDMA/Analog networks. It is normal for cellular providers to deploy new systems where they have the most subscribers and as such, GSM is being deployed firstly in cities, secondly on major highways and lastly in rural areas. This method of deployment serves the most people in the shortest period of time and all should be good, however there is a shortfall. A GSM phone user can find him/herself in an area where their old TDMA phone worked but the new GSM phone does not work and even though the cellular provider is the same and their TDMA/Analog coverage is present the GSM phone cannot receive or transmit on this system.

Special note as of September 2005- GSM coverage has greatly increased since the above note of 2004, however, defficiencies still exist especially in very remote areas where there is no GSM infrastructure or Providers. Although this is rare, one can find themselves in an analog area where a neighbor is communicating with an analog capable phone from a CDMA provider and the GSM phone will not operate.

Having said this, if you are a GSM subscriber who travels to remote areas and you use a dual band GSM phone with a Cellular Band BST850 booster, your coverage will be as good as it can possibly be.