SI on Signalling and procedure for interference avoidance for in-device coexistence

In order to allow users to access various networks and services ubiquitously, an increasing number of UEs are equipped with multiple radio transceivers. For example, a UE may be equipped with LTE, WiFi, and Bluetooth transceivers, and GNSS (Global Navigation Satellite Systems) receivers. One resulting challenge lies in trying to avoid coexistence interference between those collocated radio transceivers. Figure 4-1 below shows an example of coexistence interference.

3GPP initiated a Study Item (SI) in Release-10 timeframe to investigate the effects of the interference due to multiple radios and signalling. This study is detailed in 3GPP TR 36.816 (see link at the end).

The following scenarios were studied:

- LTE coexisting with WiFi

- LTE coexisting with Bluetooth

- LTE Coexisting with GNSS

Based on the analysis in SI, some examples of the problematic coexistence scenarios that need to be further studied are as follows:

- Case 1: LTE Band 40 radio Tx causing interference to ISM radio Rx;

- Case 2: ISM radio Tx causing interference to LTE Band 40 radio Rx;

- Case 3: LTE Band 7 radio Tx causing interference to ISM radio Rx;

- Case 4: LTE Band 7/13/14 radio Tx causing interference to GNSS radio Rx.

In order to facilitate the study, it is also important to identify the usage scenarios that need to be considered. This is because different usage scenarios will lead to different assumption on behaviours of LTE and other technologies radio, which in turn impact on the potential solutions. The following scenarios will be considered:

1a) LTE + BT earphone (VoIP service)

1b) LTE + BT earphone (Multimedia service)

2) LTE + WiFi portable router

3) LTE + WiFi offload

4) LTE + GNSS Receiver

The SI also proposes some ways of reducing the interference and is work in progress at the moment.

参考：http://www.3gpp.org/ftp/Specs/archive/36_series/36.816/