Content for TR 22.803 Word version: 12.2.0
1 Scope
2 References
3 Definitions, Symbols and Abbreviations
3.1 Definitions
3.2 Symbols
3.3 Abbreviations
4 Overview
4.1 Data paths for ProSe Communications
4.2 Control paths for ProSe Communication
4.3 Public Safety use of ProSe
...
...
1 Scope p. 8
The objective is to study use cases and identify potential requirements for operator network controlled discovery and communications between UEs that are in proximity, under continuous network control, and are under 3GPP network coverage, for:
- Commercial/social use
- Network offloading
- Public Safety
- Integration of current infrastructure services, to assure the consistency of the user experience including reachability and mobility aspects Additionally, the study item will study use cases and identify potential requirements for:
- Public Safety, in case of absence of E-UTRAN coverage (subject to regional regulation and operator policy, and limited to specific public-safety designated frequency bands and terminals)
2 References p. 8
The following documents contain provisions which, through reference in this text, constitute provisions of the present document.
- References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific.
- For a specific reference, subsequent revisions do not apply.
- For a non-specific reference, the latest version applies. In the case of a reference to a 3GPP document (including a GSM document), a non-specific reference implicitly refers to the latest version of that document in the same Release as the present document.
[1]
TR 21.905: "Vocabulary for 3GPP Specifications".
[2]
3GPP website announcement "FCC selects LTE for USA Public Safety": http://www.3gpp.org/FCC-selects-LTE-for-USA-Public
[3]
3GPP website link to FCC announcement of selection of LTE for USA public safety: "FCC TAKES ACTION TO ADVANCE NATIONWIDE BROADBAND COMMUNICATIONS FOR AMERICA'S FIRST RESPONDERS" http://www.3gpp.org/IMG/pdf/psltedoc-304244a1.pdf
[4]
FCC "Third Report and Order and Fourth Further Notice of Proposed Rulemaking" pertaining to Docket Numbers: WT Docket No. 06-150, PS Docket No. 06-229 and WP Docket No. 07-100. The Report and Order was adopted on January 25, 2011 and released on January 26, 2011. http://hraunfoss.fcc.gov/edocs_public/attachmatch/FCC-11-6A1.pdf
[5]
National Public Safety Telecommunications Council, 700 MHz Statement of Requirements for Public Safety (SoR): http://www.npstc.org/statementOfRequirements.jsp
[6]
U.S. Department of Homeland Security Technology Solutions and Standards Statement of Requirements: http://www.safecomprogram.gov/library/lists/library/DispForm.aspx?ID=302
[7]
TETRA Release 1: Direct Mode Operation http://www.tetramou.com/about/page/12026
[8]
CEPT ECC WG FM PT 49: Radio Spectrum for Public Protection and Disaster Relief (PPDR), Report from FM Project Team 49 (2nd and 3rd meetings) http://www.cept.org/ecc/groups/ecc/wg-fm/fm-49
[9]
TS 36.101: "Evolved Universal Terrestrial Radio Access (E-UTRA); User Equipment (UE) radio transmission and reception".
[10]
TS 22.278: "Service requirements for the Evolved Packet System (EPS)".
[11]
TS 22.115: "Service aspects; Charging and billing".
3 Definitions, Symbols and Abbreviations p. 9
3.1 Definitions p. 9
For the purposes of the present document, the terms and definitions given in TR 21.905 and the following apply. A term defined in the present document takes precedence over the definition of the same term, if any, in TR 21.905.
Proximity:
proximity is determined ("a UE is in proximity of another UE") when given proximity criteria are fulfilled. Proximity criteria can be different for discovery and communication.
Range Class:
Rough indication of distance for use in ProSe Discovery, for example, based on geographical distance, radio conditions.
ProSe Discovery:
a process that identifies that a UE is in proximity of another, using E-UTRA.
ProSe Communication:
a communication between two UEs in proximity by means of a E-UTRAN communication path established between the UEs. The communication path could for example be established directly between the UEs or routed via local eNB(s).
ProSe-enabled UE:
a UE that supports ProSe Discovery and/or ProSe Communication. Unless explicitly stated otherwise in this TR, a UE refers to a ProSe-enabled UE.
ProSe-enabled Network:
a network that supports ProSe Discovery and/or ProSe Communication. Unless explicitly stated otherwise in this TR, a network refers to a ProSe-enabled network.
Open ProSe Discovery:
is ProSe Discovery without explicit permission from the UE being discovered.
Restricted ProSe Discovery:
is ProSe Discovery that only takes place with explicit permission from the UE being discovered.
ProSe Group Communication:
a one-to-many ProSe Communication, between two or more UEs in proximity, by means of a common communication path established between the UEs.
ProSe Broadcast Communication:
a one-to-all ProSe Communication, between all authorized UEs in proximity, by means of a common communication path established between the UEs.
ProSe UE-to-UE Relay:
is a form of relay in which a ProSe-enabled Public Safety UE acts as a ProSe Communication relay between two other ProSe-enabled Public Safety UEs.
ProSe UE-to-Network Relay:
is a form of relay in which a ProSe-enabled Public Safety UE acts as a communication relay between a ProSe-enabled Public Safety UE and the network using E-UTRA.
3.2 Symbols p. 9
For the purposes of the present document, the following symbols apply:
None
3.3 Abbreviations p. 9
For the purposes of the present document, the abbreviations given in TR 21.905 and the following apply. An abbreviation defined in the present document takes precedence over the definition of the same abbreviation, if any, in TR 21.905.
CPR
Consolidated Potential Requirement
GW
Gateway
GWCN
Gateway Core Network
HD
High Definition
MNO
Mobile Network Operator
MOCN
Multi-Operator Core Network
PR
Potential Requirement
ProSe
Proximity Services
PS
Public Safety
RCS
Rich Communication Services
SGW/PGW
Serving Gateway / Packet data network Gateway
4 Overview p. 10
4.1 Data paths for ProSe Communications p. 10
4.1.1 Default data path scenario p. 10
As currently specified, when two UEs in close proximity communicate with each other, their data path (user plane) goes via the operator network. The typical data path for this type of communication is shown in Figure 1, where eNB(s) and/or GW(s) are involved.
Figure 1: Default data path scenario in the EPS for communication between two UEs.
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
4.1.2 ProSe Communication scenario p. 10
If UEs are in proximity to each other, they may be able to use a "direct mode" or "locally-routed" path.
For example, in 3GPP LTE spectrum, the operator can move the data path (user plane) off the access and core networks onto direct links between the UEs. This direct data path is shown in Figure 2.
Figure 2: The "direct mode" data path in the EPS for communication between two UEs.
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
Another example is when the data path is locally-routed via the eNB(s). This locally-routed data path is shown in Figure 3:
Figure 3: A "locally-routed" data path in the EPS for communication between two UEs when UEs are served by the same eNBs.
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
4.2 Control paths for ProSe Communication p. 11
For the ProSe Communication scenarios depicted in Figure 2 and Figure 3 in clause 4.1, several control path scenarios may apply. The following text and figures provide examples of potential control paths for different situations, understanding that other 3GPP Working Groups are responsible for defining the specific control paths associated with ProSe.
When the UEs involved in the ProSe Communication are served by the same eNB and network coverage is available, the system can decide to perform ProSe Communication using control information exchanged between the UE, eNB and the EPC (e.g., session management, authorization, security) as shown by the solid arrows in Figure 4. For charging, signalling modifications should be minimized with respect to the existing architecture. The UEs can in addition exchange control signalling via the ProSe Communication path as shown by the dashed arrow in Figure 4.
Figure 4: Example control path for network-supported ProSe communication for UEs served by the same eNB.
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
When the UEs involved in the ProSe Communication are served by different eNBs and network coverage is available, the system can decide to perform ProSe Communication using control information exchanged between the UE, eNB and the EPC (e.g., session management, authorization, security) as shown by the solid arrows in Figure 5. In this configuration, the eNBs may coordinate with each other through the EPC or communicate directly for radio resource management as shown by the dashed arrow between the eNBs in Figure 5. For charging, signalling modifications should be minimized with respect to the existing architecture. The UEs can in addition exchange control signalling via the ProSe Communication path as shown by the dashed arrow between UE1 and UE2 in Figure 5.
Figure 5: Example control path for network-supported ProSe Communication for UEs served by different eNBs.
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
If network coverage is available to a subset of the UEs, one or more Public Safety UEs may relay the radio resource management control information for other UEs that do not have network coverage.
If network coverage is not available, the control path can exist directly between Public Safety UEs, as shown with the solid arrow in Figure 6. In this configuration, the Public Safety UEs can rely on pre-configured radio resources to establish and maintain the ProSe Communication. Alternatively, a Public Safety Radio Resource Management Function, which can reside in a Public Safety UE, can manage the allocation of radio resources for Public Safety ProSe Communication as shown with the dashed arrows in Figure 6.
Figure 6: Example control path for Public Safety ProSe Communication for UEs without network support.
(⇒ copy of original 3GPP image)
(⇒ copy of original 3GPP image)
4.3 Public Safety use of ProSe p. 13
In the United States, LTE has been selected by the FCC as the technology [2][3][4] for the Public Safety Network. In Europe, there is an ongoing discussion on spectrum to be chosen for broadband Public Safety held by CEPT ECC WG FM PT 49 [8]. Additionally, a variety of Public Safety over ProSe requirements have been defined [5][6][7]. The requirements raise the following points for consideration in developing the ProSe requirements for Public Safety use.
A Public Safety UE can operate in Public Safety spectrum for Public Safety service and in MNO commercial spectrum, for general service (e.g. voice call), however, only Public Safety spectrum is used for Public Safety ProSe.
Public Safety UEs using ProSe communicate with each other even though they belong to different HPLMNs.
A Public Safety UE can automatically use ProSe when E-UTRAN coverage is not available, or the user can manually set the UE to use direct discovery and communication even when E-UTRAN coverage is available.
In addition, the following assumptions are made for Public Safety ProSe:
- All Public Safety users utilize ProSe-enabled UEs
- ProSe supports both UE discovery and UE Communication
