iDEN

Integrated Digital Enhanced Network (iDEN) is a mobile telecommunications technology, developed by Motorola, which provides its users the benefits of a trunked radio and a cellular telephone. It has been called the first mobile social network by technology industry analysts.^[1] iDEN places more users in a given spectral space, compared to analog cellular and two-way radio systems, by using speech compression and time division multiple access (TDMA).

History

The iDEN project originally began as MIRS (Motorola Integrated Radio System) in early 1991. The project was a software lab experiment focused on the utilization of discontiguous spectrum for GSM wireless. GSM systems typically require 24 contiguous voice channels, but the original MIRS software platform dynamically selected fragmented channels in the radio frequency (RF) spectrum in such a way that a GSM telecom switch could commence a phone call the same as it would in the contiguous channel scenario. The original MIRS System was renamed IDEN in 1994 by Roger Cameron Wood, a young engineering program manager leading the product development effort who also gave the handsets their distinctive industrial design, group software features, and "chirp" audio.

Operating frequencies

iDEN is designed and licensed to operate on individual frequencies that may not be contiguous. iDEN operates on 25 kHz channels, but only occupies 20 kHz in order to provide interference protection via guard bands. By comparison, TDMA Cellular (Digital AMPS) is licensed in blocks of 30 kHz channels, but each emission occupies 40 kHz, and is capable of serving the same number of subscribers per channel as iDEN. iDEN uses frequency-division duplexing to transmit and receive signals separately, with transmit and receive bands separated by 39 MHz, 45 MHz, or 48 MHz depending on the frequency band being used.^[2]

iDEN supports either three or six interconnect users (phone users) per channel, and six dispatch users (push-to-talk users) per channel, using time division multiple access. The transmit and receive time slots assigned to each user are deliberately offset in time so that a single user never needs to transmit and receive at the same time. This eliminates the need for a duplexer at the mobile end, since time-division duplexing of RF section usage can be performed.

Hardware

The first commercial iDEN handset was Motorola's L3000, which was released in 1994. Lingo, which stands for Link People on the Go, was used as a logo for its earlier handsets. Most modern iDEN handsets use SIM cards, similar to, but incompatible with GSM handsets' SIM cards. Early iDEN models such as the i1000plus stored all subscriber information inside the handset itself, requiring the data to be downloaded and transferred should the subscriber want to switch handsets. Newer handsets using SIM technology make upgrading or changing handsets as easy as swapping the SIM card. Four different sized SIM cards exist, "Endeavor" SIMs are used only with the i2000 without data, "Condor" SIMs are used with the two-digit models (i95cl, for example) using a SIM with less memory than the three-digit models (i730, i860), "Falcon" SIMs are used in the three-digit phones, (i530, i710) and will read the smaller SIM for backward compatibility, but some advanced features such as extra contact information is not supported by the older SIM cards. There is also the "Falcon 128" SIM, which is the same as the original "Falcon", but doubled in memory size, which is used on new 3 digit phones (i560, i930).

iDEN base radio at a cell site

The interconnect-side of the iDEN network uses GSM signalling for call set-up and mobility management, with the Abis protocol stack modified to support iDEN's additional features. Motorola has named this modified stack 'Mobis'.

Each base site requires precise timing and location information to synchronize data across the network. To obtain and maintain this information each base site uses global positioning system satellites to receive a precise timing reference .

Operators

In the United States of America there are a few iDEN service providers, SouthernLINC Wireless and several small public and private iDEN service providers. Numerous private systems exist, including one run by ARINC, covering all major airports. Countries which have operating iDEN networks include Canada, Argentina, Peru, Mexico, Brazil, Jordan, Chile, Israel, Philippines, Singapore, Saudi Arabia, Japan, El Salvador, China and most recently India and Guatemala.

Sprint Nextel provided iDEN service across the United States, but its iDEN network was decommissioned on June 30, 2013.

iDEN network operators

Network operator	Country	Push-to-Talk product name
Airpeak	United States	Talk Direct
Airtel Wireless Ltd.	Canada	Churp
ARINC	United States
Avantel	Colombia	Comunicación Inmediata
Bravo Telecom	Saudi Arabia	Push To Talk
China Satcom Guomai Comm Co. Ltd	China
Connect Net	United States
Fleetcom Inc.	Canada	Push-to-Talk
GRID Communications	Singapore	Push To Talk
Iconnect	China Hong Kong (SAR)
Iconnect	Guam	iConnect PTT
Inquam Telecom	Morocco
Intelfon	El Salvador	RED
Intelfon	Guatemala	RED
KT Powertel	South Korea
Mirs	Israel	Walkie-Talkie
Monttcashire	Ecuador
NEXNET	Japan
Nextel Argentina	Argentina	Direct Connect
Nextel Brazil	Brazil	Direct Connect
Nextel Chile	Chile	Direct Connect
Nextel Mexico	Mexico	Conexión Directa
Nextel Peru	Peru	Conexión Directa
Procall Pvt. Ltd.	India	Digital Push To Talk
Proxtel Wireless	Puerto Rico	Direct Connect
Shenzhen Yunliantong Comm Service	China
SouthernLINC Wireless	United States	InstantLINC
Spacedata	United States
Telus	Canada	Mike
Vona	Brazil	Radio Despacho
XPress	Jordan	XPress Direct Connect

See also

• Motorola iDEN phone models
• Push to Talk over Cellular
• Radio Service Software
• WiDEN

References

1. ↑ Lawson, Stephen (December 7, 2010). "Sprint's iDEN finally headed for sign-off". Computerworld.com. Retrieved 5 September 2012. 
2. ↑ Motorola iDEN Technical Overview

External links

• Motorola iDEN phones
• List of iDEN providers globally
• List of Urban ID codes