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Public Safety LTE

This blog is about Public Safety LTE. Main focus is on public safety technology topics such as LTE spectrum, networks, smartphones, apps and public safety specific 3GPP features.

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December 31, 2015

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Public Safety prioritization

December 28, 2015

LTE QoS and prioritization for mission critical communication Public safety (PS) users have the most stringent requirements for network & service accessibility and service quality. Various mechanisms can be used to fulfill these requirements in different network conditions. Those mechanisms must be able to differentiate both users and applications based on certain priorities. PS users can have different priority levels, which can also change dynamically. For example paramedic engaged in emergency mission has a higher priority than policemen on a lunch break. LTE networks can be shared serving both PS users and commercial subscriber with same resources (e.g. same carriers), in which case there is also a need to prioritize PS users over regular subscribers. Key reason for adopting LTE for mission critical communication is of course broadband capability for data applications. At the same time LTE certainly supports also voice calls (both group calls & one-to-one ca...

APNs in MCPTT smartphone

January 21, 2017

LTE smartphones provide mobile broadband connection to Internet. The prerequisite is that the UE has correct settings, which depend on the mobile operator. Nowadays device vendors and operators have made the use of mobile data so easy that usually users do not need to do any manual configuration. Each smartphone has an internet APN (Access Point Name) configuration, which matches with the operator's network configuration. In general certain APN configuration allows UE to connect (when included in subscription) to certain IP network called packet data network (PDN). So, smartphones know operator's internet APN setting, which enables UE to connect to Internet. Operators have also other APNs and respective PDNs, which offer operator specific services. Some of those services are standardized. On old, still existing service is MMS (Multimedia Messaging Service). MMS is supported by all smartphones and probably automatically configured in all devices and networks. The question is...

Mission Critical Push To Talk and EPS bearers

January 24, 2016

Mission critical push to talk architecture defines several reference points and uses multiple protocols over different EPS bearers. 23.179 specifies that UE connets to MCPTT specific APN in order to use MCPTT service. It is defined that SIP signaling uses QCI 69 bearer. Additionally HTTP is used for signaling. 23.179 defines also that QCI 8 or better is used for HTTP messaging. Voice media is transmitted over secure RTP either using unicast GBR QCI65 bearer or optionally in multicasting downlink media over MBMS GBR QCI65 bearer. Same bearer (unicast or multicast) is used also floor control. Following figure depicts how these MCPTT reference points can be mapped to unicast and multicast bearers. Although the 23.179 states that SIP and HTTP can be mapped to different unicast bearers that have different QoS, it can be also interpreted that QCI69 is better than QCI8 and therefore it should be possible to carry both SIP and HTTP signalling over the default QCI69 bearer. After LT...