Will LTE signal the end of GSM?

At the end of last year NTT DoCoMo launched their LTE network. They had announced back in May, at the LTE World Summit that they have a roadmap in place to migrate remaining customers on thier 2G network to 3G and LTE and plan to switch off the 2G network within 2 years. So we're looking at a switch off date of May 2012. This isn't as aggressive and ambitious as it seems, as DoCoMo has an unusually high proportion of its subscrbers already on 3G. Coupled with the fact that DoCoMo uses the rather niche PDC technology for its 2G network, you can understand why they want to part ways with it.

So why aren't other mobile operators in mature markets as keen as NTT DoCoMo is on this strategy?

There are three seasons.

1. No operator will switch off their GSM network until there is complete ubiquity of at least 3G.
2. GSM provides an excellent voice service and in markets such as UK.
3. The difference in QoS between EGDE and 3G is considerable, EDGE is still good enough for basic web browsing etc.

Operators seem to be resigned to the fact that for now they will have to operator 3 different networks (4 if they operate a series of WiFi hotspots!). In this situation optimising traffic-flows across different networks and having the right policies in place for managing capacity effectively is essential.

If DoCoMo is successful then operators may think again, but for now is seems that GSM still has a long life ahead.

参考：http://lteconference.blogspot.com/2011/01/will-lte-signal-end-of-gsm.html

10 business models that rocked 2010 - by @nickdemey (boardofinnovation.com)

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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/