Bluetooth and DECT - A History of Wireless Devices

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Many of us can think back to a time before the Internet, MTV (Video Killed the Radio Star), and the topic of this blog - personal wireless communications (cordless phones, wireless headsets, Cellular Phones, Bluetooth and DECT). Who amongst us can remember being tied via a "phone cord" to a telephone when making a phone call. Nowadays, if there are cords to a telephone, it is typically an Ethernet cable to our Internet Protocol Phone or IPPhone or a charging cable to our cellular phone.  Many of us prefer not to hold a cordless phone to our ear. Whether it be a true cordless phone or a cellular phone, we demand that it support a wireless headset so that we can be more mobile and have our hands free for other activities - like writing blogs ;-).

While I usually talk with customers about different types of Skype for Business certified VoIP phones, headsets, hosted telecom services in Office 365, etc., I find myself often saying terms as if everyone knows them and knows the history of them. I realize that this is not always the case and decided to take a step back in this blog to provide a brief understanding of how these different forms of technology developed. While researching devices to use in your organization or for your own personal use, after reading this blog it is my hope you will have more of an understanding about the features and technology each device advertises today.

As far back as the 1890s when Marconi first developed his wireless telegraph, humans have wanted to communicate wirelessly.  The ability to communicate at great distances had obvious benefits and wireless communications allowed for this. Though it would take another 31 years (1927) before the first commercial radiotelephone service between Britain and the United States could be put into use. After that, it was another 19 years (1946) before it was used domestically in St. Louis. A year later the transistor was invented and the ability to create wireless devices small enough to be held in your hand had begun. This began to change how people viewed wireless technology. Now the ability to move around with a "cordless phone" was within reach. Our mobility while communicating would become common place as the cellular phone industry was expanding. Fast forward to 1993 when Internet Protocol version 4 (IPv4) is established as the defacto standard for over the Internet communications in conjunction with the Transport Control Protocol, thus giving is the popular TCP/IP tag.

IPv4 set the stage for wireless internet that came about in 1997 when the Institute of Electrical and Electronics Engineers or IEEE came out with their 802.11 standard for wireless local area networks. Meanwhile in Europe, around the same time period, the European Telecommunications Standards Institute ETSI was working on creating the Digital European Cordless Telecommunications DECT which is also known as the Digital Enhanced Cordless Telecommunications standard. DECT is now the standard for all cordless phones in Europe. While DECT continued to evolve, its use range from simple handsets to elaborate wireless networks in Europe. DECT 6.0 was coined in the United States for use in personal device communications. It should be noted that DECT 6.0 devices are not allowed in many European countries due to interference with public wireless systems.

In 1998 Bluetooth was developed in a joint venture by Ericsson, IBM, Nokia, Intel and Toshiba. Bluetooth as a standard for wireless data exchange between hand held computers or cellular phones and stationary computers such as the common desktop of today. In 1999 the Wi-Fi Alliance was founded by 3Com (now HP), Aironet (now Cisco), Intersil, Lucent Technologies (now Nokia), Nokia, and Symbol Technologies (now Zebra) which then branded the phrase "WiFi" for WLAN or 802.11 communications, so as to differentiate Bluetooth, DECT and IEEE   802.11 technologies.

Because Bluetooth and DECT are both wireless technologies like WiFi, they are each restricted to certain frequencies within the Radio Frequency Spectrum. DECT 6.0 uses the 1.9 Gigahertz frequency while Bluetooth uses 2.4 Gigahertz and WiFi uses both 2.4 Gigahertz and 5 Gigahertz Frequencies.

The table below breaks down the power levels and frequency per wireless technology. Please note that there are many factors involved in each technology listed so the values will range depending on the device configuration and application.

When devices are using the same frequencies in close proximity, you run the risk of Radio Frequency Interference or RFI. As it pertains to headsets, RFI  can cause degradation in the audio quality and even the inability to connect one device to another. Jabra, Plantronics and Sennheiser each have density studies that can help you determine the likelihood of encountering density conflicts caused by overcrowding and RFI . These density studies will help you to understand where overcrowding may occur and how mixing DECT and Bluetooth headsets may solve the overcrowding issue. The density studies for Jabra, Plantronics and Sennheiser can be found by clicking on the following links: Jabra, Plantronics, Sennhesier.

This figure below shows and example of WiFi overcrowding. Bluetooth and DECT overcrowding would look the same if there were multiple devices within a specific area.

Figure 1

The question is not which should we use, Bluetooth or DECT, but how many of each and where to avoid density and overcrowding issues?   Jabra, Plantronics and Sennheiser each offer both DECT and Bluetooth versions of their headsets. Below are examples of each:

Jabra's Pro 9470 Series comes in both DECT 6.0 and Bluetooth versions.


As does the Plantronics Savi 700 series


While Sennheiser's MB Pro 2 and SD Pro 2 are Bluetooth and DECT 6.0, respectively.










Note: The historical facts stated above have been referenced from the Wireless History Foundation and Wikipedia.


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