DECT vs PHS: Digital Cordless Phone Differences

This article breaks down the key differences between DECT (Digital Enhanced Cordless Telecommunications) and PHS (Personal Handy-Phone System) digital cordless telephone technologies.

What is DECT?

DECT, short for Digital Enhanced Cordless Telecommunications, was developed by the European Telecommunications Standards Institute (ETSI) in 1993. It’s a widely adopted system, especially in Europe, but also used in countries across Australia, Asia, and South America.

A key feature of DECT is its ability to connect multiple handsets to a single base station. It also supports handover, similar to cellular networks. Common applications of DECT include:

• Domestic Systems: Connecting to a base station that interfaces with the Public Switched Telephone Network (PSTN).
• Business Systems: Connecting to a Private Branch Exchange (PBX) with fixed radio parts. Handsets dynamically connect to these base stations.
• Cellular-like Systems: Public applications with high deployment density.
• Local Loop Replacement: Replacing wired connections between subscribers and the PSTN.

Here’s a technical overview of the DECT standard:

• Mobile Frequency Range: 1880 to 1900 MHz
• Duplex Scheme: TDD (Time Division Duplex)
• Multiple Access Technique: TDMA/FDM (Time Division Multiple Access/Frequency Division Multiplexing)
• Number of Channels: 10
• Number of Users per Channel: 12
• RF Channel Spacing: 1.728 MHz
• Modulation Type: GFSK (Gaussian Frequency-Shift Keying) with 0.5 Gaussian Filter
• Channel Data Bit Rate: 1.152 Mbps

(For a more in-depth look, refer to a dedicated DECT tutorial.)

What is PHS?

PHS, or Personal Handy-Phone System, is another cordless telephone system designed for mobile cellular environments. Like DECT, it supports handover between cells. However, PHS cells are typically smaller than those used in GSM (Global System for Mobile Communications) networks.

PHS is particularly well-suited for densely populated urban areas, whereas GSM is better suited for rural environments.

Here are the key features of the PHS standard:

• Mobile Frequency Range: 1895 to 1918 MHz
• Duplex Scheme: TDD (Time Division Duplex)
• Multiple Access Technique: TDMA/FDM (Time Division Multiple Access/Frequency Division Multiplexing)
• Number of Channels: 300
• Number of Users per Channel: 4
• RF Channel Spacing: 300 KHz
• Modulation Type: pi/4 DQPSK (Differential Quadrature Phase Shift Keying)
• Channel Data Bit Rate: 384 Kbps

Key Differences: DECT vs. PHS vs. GSM

The table below summarizes the key differences in cell size between DECT, PHS, and GSM:

• DECT Cells: Radius of 25-100 meters
• GSM Cells: Radius of 2-10 kilometers
• PHS Cells: Radius of 10-100 meters

Initially, PHS was developed by NTT in Japan to compete with GSM. However, it faced challenges due to limited coverage and the lack of roaming capabilities. Modern PHS systems have evolved to support value-added services like email, internet access, and text messaging.