Careful deployment of 802.11-based high-speed Bluetooth (1)

Bluetooth SIG is developing the next generation of Bluetooth specifications. This new specification, known as high-speed Bluetooth, will support high-speed file transmission and video stream applications. At first, the Bluetooth SIG only adopted the WiMedia ultra-broadband (UWB) technology to implement this new protocol. However, it recently announced that it could also use 802.11 as a transitional solution to add Bluetooth protocol based on the Wi-Fi wireless signal existing in portable devices.

This means that both WiMedia and 802.11 are now candidates for high-speed Bluetooth specifications, MAC/PHY (AMP ). The principle is to allow consumer devices to use the existing bluetooth technology, while using the second wireless technology to achieve faster throughput. However, many people in the industry are very concerned about the well-known interference issues, as the 802.11 wireless signal in Bluetooth devices and other IMT-2000 services that work in adjacent frequencies (such as WiMAX, LTE, UMTS and WCDMA) it is easy to interfere with each other. Their concern is that if consumers lack experience in using 802.11 AMP to initially implement high-speed Bluetooth, even if they have the short-term benefits of fast market listing, for the success of this technology, but there is a greater long-term risk. Bluetooth has a very good position in the consumer market (Bluetooth SIG welcomed 9,000th members last year), and the use of a transitional technology to shorten the time to market is highly risky.

Use Model

Although WLAN and IMT-2000 generally do not work at the same time because they both have access to the network infrastructure. However, because high-speed Bluetooth and IMT-2000 services support independent applications, it often works at the same time. This means that if a high-speed bluetooth device is using a 802.11 AMP, it is likely that there are other IMT-2000 services working in adjacent frequencies in its environment. For ease of description, consider the following models.

Figure 1 shows two multi-frequency mobile phones that are very close to each other. A mobile phone is making a call through WiMAX, and the second mobile phone will use 802.11-based high-speed Bluetooth Technology to send files to PCs.

When the second mobile phone transfers a file to a PC, the WiMAX call will be dropped, even if there is a few meters between the two. In Figure 2, the mobile phone is using high-speed Bluetooth to print files while making a WiMAX call.

To avoid phone disconnection, you must wait until the call ends before printing. Or if printing is started, the phone cannot answer the call.

Figure 1

One mobile phone uses 802.11-based high-speed Bluetooth to send files to the laptop, while the other mobile phone is in WiMAX calls. The two mobile phones will interfere with each other even if they are 8 meters apart.

In the above two usage models, any interference between the Bluetooth system and WiMAX or cellular services will cause great damage to the user experience of the end user. In fact, users need to be able to use multiple technologies at the same time without interfering with each other.

One of the fundamental causes of interference between bluetooth 802.11 AMP and IMT-2000 services is that they work in adjacent spectrum (see table 1 ), using 802.11 for high-speed Bluetooth transmission will seriously affect other services that work in adjacent licensed frequencies.

Table 1 spectrum allocation

In addition, even if the Bluetooth SIG intends to apply the 802.11 AMP limit to file transmission applications, once this high-speed wireless feature is introduced to the market, users may use it to transmit video data streams (as described in Bluetooth printed materials ). Due to the continuity of the transmission, these streaming applications above the 802.11 AMP will have greater potential interference than the file transfer.