Digital Enhanced Cordless Telecommunications(DECT) is one of the applications of computer networks that comes under wireless networks widely used for both domestic and business purposes. It is designed for short-range which acts as an access method to major networks. Due to the flexible nature of DECT, it becomes a widely used application around the globe.
History of DECT:
The standard for DECT is first established in 1992 which was developed by ETSI (European Telecommunication Standard Institute). The research had been started in 1987 until the first establishment. Initially, DECT is known as Digital European Cordless Telephony which evolved into Digital European Cordless Telecommunications. And in 1995, the name was finally changed to Digital Enhanced Cordless Telecommunications. In 2007, a new standard for DECT was launched (NG-DECT). The next improvement was done in 2011 called DECT Ultra-low energy (DECT-ULE). This improvement added its benefit in health, automated battery, tracking of energy used.
DECT Explanation:
Though DECT was first designed for high roaming in networked stations, it is widely used as the wireless system which connects the office/ home to the network station and allows roaming within that place. This system uses radio waves to use the fixed network. It uses a total of 10 channels and the range of frequency is from 1880 to 1900MHz. Generic Access Profile (GAP) is used by most producers for the interoperability for basic telephone abilities. The GAP also determines the security, mobility requirements. The prerequisite for private and public networks varies accordingly. DECT also allows cordless LAN (Local Area Network) and cordless internet service. DECT is used in cordless voice, fax, multimedia communications, PBX (Business Telephone System).
Operating Principles of DECT:
- Network access is cellular structured with large capacity.
- DECT has the nature to allow a high mobility of networks.
- The source is safe and secure with access to the radio.
- When the bandwidth requirement varies, DECT can meet the demand with flexibility.
- Integrated voice and data facility with a mixed media capability.
- It has the ability of robustness even in averse radio environments by effective control of equipment.
- The spectrum efficiency of DECT is high and flexible.
- Developed addressing of identities.
- The standard developed has high flexibility which helps in further enhancement in the future.
- It has Dynamic channel allocation to reduce interference.
Techniques used in DECT:
There is a total of 120 duplex channels in DECT this means 120 users can interfere with each other’s transmission, but they don’t interfere due to the allotment of separate channels. The techniques used in DECT are TDMA (Time Division Multiple Access), FDMA (Frequency Division Multiple Access), TDD (Time Division Duplex). There are 10 frequency slots, 24 times slots. The first twelve time slots are for downlink communication (from satellite to ground station) and the other twelve time slots are for uplink communication (end-user to network/ satellites).
There are two methods to divide the frequency between a large number of users in a cordless system. Using TDMA, DECT gives portable stations to listen to the channels when it is neither sending nor receiving. This leads to Dynamic Channel Allocation (DCA), which means when an end-user/ terminal gets interfered with or faces any problems, the system can easily relocate to a different channel to solve the issue. Using TDMA, it has possible to transmit and receive to multiple users using the same radio.
The three specifications for the coverage of the area in DECT are
- Radio frequency.
- Receiver sensitivity.
- Transmitting power.
When DECT is compared with the Global System for Mobile Communication, it has low area coverage and range. But it is widely useful in indoor communications. DECT can provide 12 voice connections at the same time per transceiver.
Features of DECT:
- DECT is made up of two parts, one portable and the other is fixed. The radio fixed part is the base station. The portable part is the mobile handset. The base station establishes the connection between the telephone networks and the mobile handsets.
- The handover is smooth and the security feature is well developed. This also has increased mobility, adjustable bandwidth, high grade of voice, and high battery quality which increases the number of users.
- The cell radius ranges from 25 to 100 meters. It has a bit rate of 32 kbps with a traffic density of 100000 Erlangs/Km2.
- The channel allocation method is dynamic with a channel spacing of 1.728 MHz. And the radio carrier frequency ranges from 1.88 to 1.9GHz. The total number of carriers is 10 and each carrier contains 12 channels.
- The time slot range is 2 x 12, a total of 24 for upstream and downstream.
Applications of DECT:
- DECT is used in the development of cordless phones which are widely used for residential, work, and business purposes.
- It is used in the development of many industry applicants, baby monitors, remote controls.
- It is used in Public Switched Telephone Network (PSTN) which is the global telephone system connecting various public telephone networks.
- It is used in business telephone systems where multiline telephone networks are used in work environments which are called Private Automated Branch Exchange (PABX). It is used in call centers and other business firms.
- It is used in Integrated Service Digital Network where the transmission of voice, multimedia data gets done over a Public Switched Telephone Network (PSTN).
- It is used in Global System for Mobile Transmission and in Wireless Local Loop (WLL) where the telephone and internet services are provided to the telecommunication customers.
- It is also used in fax, e-mail, Local Area Networks (LAN), etc.
- The end-user can move the handset to a specific range which gives the feature of Cordless Terminal Mobility.
Advantages of DECT:
- Reliability: DECT is designed for voice. It makes sure that voice will not interfere with another communication process.
- Isolated frequency: Since DECT has its own spectrum, it operates on its isolated frequency which reduces the competition of airways between computer and wi-fi devices.
- Less Power Consumption: The handset is designed in such a way it acquires less power compared with wi-fi which allows the user to have more talk time.
- Cost-efficient: The cost that needs to be afforded to use these services is less compared to others which causes the increase of subscribers from enterprises to residents.
- Less exposure to HF waves: DECT telephone users face less exposure to High-Frequency waves than mobile transmission users. This is due to the short-range feature of DECT.
- Stability and Security: DECT is used for seamless communications and it is highly secure. The stability of DECT is due to the exclusive base station only being available for the handsets.
- High Quality: The high quality of the DECT ensures uninterrupted roaming between the base stations.
Disadvantages of DECT:
- Multi-Cell Systems: This is one of the negative aspects of DECT. Though it is highly reliable and has mobility, problems arise when we want to provide multi-cell systems with numerous handsets and base stations. When multicellular systems are involved, it becomes a pitfall and gives a look that wi-fi is more engaging.
- Less Coverage: Due to its short-range feature, it covers less area and the transmission is also limited.
- Eye on battery: This is one small disadvantage where the user has to keep an eye on batteries and they should make sure that the handsets are on their base when not used.