WiFi 802.11ax and 5G convergence - an inevitable stride of NSA mode 5G.

Despite of continuous improvement in data services with high data rates and more spectrum utilization the networks are not free from the congestion. The tremendous growth of video traffic and smart devices has resulted in heavy pressure on data networks resources. As a result of this continuous thrust for data capacity, 3GPP has come up in its recent releases with idea of incorporating more spectrum bands including unlicensed and shared spectrum.

WiFi has been of interest since the early days and being there in the radar of 3GPP since release 8 but has been incorporated in the propensity of RAN in release 13 and onward. LTE-U, LAA and LWA are some of the 3GPP networking features focusing on unlicensed spectrum.

WiFi is a mature technology in itself has been in continuous growth and pace with the next generation networks. IEEE 802.11 standards has been evolving and have improved much from the days of 802.11n to 802.11ac & 802.11ad (in 60GHz) and recent one, taken to be efficient for highly dense environment, 802.11ax.

802.11ax, also called High-Efficiency Wireless (HEW), looking beyond the raw link speeds of 802.11ac. It implements several mechanisms to serve more users consistent and reliable data throughput in highly dense wireless environments. High-Efficiency Wireless includes the following key features:

·         Backwards compatible with 802.11a/b/g/n/ac.

·         Increase 4X the average throughput per user in high-density scenarios, such as train stations, airports and stadiums. -Data rates and channel widths similar to 802.11ac, with the exception of new Modulation and Coding Sets (MCS 10 and 11) with 1024-QAM.

·         Specified for downlink and uplink multi-user operation by means of MU-MIMO and Orthogonal Frequency Division Multiple Access (OFDMA) technology.

·         Larger OFDM FFT sizes (4x larger), narrower subcarrier spacing (4X closer), and longer symbol time (4X) for improved robustness and performance in multipath fading environments and outdoors.

·         Improved traffic flow and channel access.

·         Better power management for longer battery life.

In fact 802.11ax going to be a distributed data rates for fare distribution of overall capacity to each user's, making an efficient system with larger spectrum band.

In next generation telecom networks era, LTE was the first technology to step in, being the complete data centric networks and has started an era of data dependent information and communication systems. DATA has become now days a utility for the end users to run its day to day business. LTE started with 10X faster than its early days technologies, to now a days 100X faster in form of Gigabit LTE.

WiFi With its new avatar 802.11ax becomes a good partner with LTE for a better convergence and provide a combination of licensed and unlicensed for a larger capacity to end users.

This also opens the gate for Wifi entry to 5G system as an associative data network with LTE as a control plane. So it's not going to be only NR with LTE but WiFi too, much in NSA mode of 5G.

3GPP completed SA mode 5G specifications for release 15. How the industry will incorporate SA and NSA?

As 3GPP announced a new milestone on 5G release 15 standardization, that is completion of Stand Alone mode specification of 5G operation. The big question arises, would there be a split in 5G deployments in near future (i.e. with the availability of equipment's and mobile terminals)? because there is no obstruction possible on NSA mode rather NSA is going to have a major coverage, in fact for large coverage areas NSA would be there and probably SA would cover smaller coverage areas through small cells.

SA mode is about no LTE for control plane but both plane would be on NR only. So SA will put LTE on spare, really? That is feasible only for smallcell deployment cases as the operators are not going to make LTE spare due to heavy investment. Rather that is the upbring of 5G in real sense. We have already witnessed gigabit LTE deployments and vested interest of operator on it through LAA and LWA due to LTE based carrier aggregation CA or multi RAT convergence.

That trends is leading towards the solid root for NSA mode, SA mode would be filling the gap and caveats but not overshadowing it anywhere. The Fixed broadband uses case of 5G NR so far has been for millimeter waves but sub 6 Ghz NR has yet to come for mobile use cases ( as we all are waiting for mobile terminals use cases). 

LTE is far established and well coordinated for network spread and coverage enhancements, 5G NR has yet to come for that level of maturity and that's gonna take long time. Still LTE and 5G both seems to be moving parallel as there seems to be no obstruction for LTE as well. Technology has matured and taken its much advance form in LTE adv pro. In fact LTE adv pro is well taken to accomplish much of 5G use cases, whether it be massiv IOT, V2X or URLLC use cases like for robotics or healthcare.

Therefore 5G is not about 5G NR only,  There is much more wider outlook for 5G, like Network Slicing, Application defined etc, etc. 5G is a big hash, technology under which create a comprehensive system, not a isolated sliver.

3GPP Mission Critical Services – Detailed List of Rel-13, Rel-14 and Rel-15 Functionalities

Rel-13 MCPTT (completed 2016)

• User authentication and service authorization
• Configuration
• Affiliation and de-affiliation
• Group calls on-network and off-network (within one system or multiple systems, pre-arranged or chat model, late entry, broadcast group calls, emergency group calls, imminent peril group calls, emergency alerts)
• Private calls on-network and off-network (automatic or manual commencement modes, emergency private calls)
• MCPTT security
• Encryption (media and control signalling)
• Simultaneous sessions for call
• Dynamic group management (group regrouping)
• Floor control in on-network (within one system or across systems) and in off-network
• Pre-established sessions
• Resource management (unicast, multicast, modification, shared priority)
• Multicast/Unicast bearer control, MBMS (Multimedia Broadcast/Multicast Service) bearers
• Location configuration, reporting and triggering
• Use of UE-to-network relays

Rel-14 MC Services (completed 2017)

MC Services Common Functionalities:

• User authentication and service authorization
• Service configuration
• Affiliation and de-affiliation
• Extended Location Features
• (Dynamic) Group Management
• Identity management
• MC Security framework
• Encryption (media and control signalling)

MCPTT Enhancements:

• First-to-answer call setup (with and without floor control)
• Floor control for audio cut-in enabled group
• Updating the selected MC Service user profile for an MC Service
• Ambient listening call
• MCPTT private call-back request
• Remote change of selected group

MCVideo, Common Functions plus:

• Group Call (including emergency group calls, imminent peril group calls, emergency alerts)
• Private Call (off-network)
• Transmission Control

MCData, Common Functions plus:

• Short Data Service (SDS)
• File Distribution (FD) (on-network)
• Transmission and Reception Control
• Handling of Disposition Notifications
• Communication Release

Rel-15 MC Services (in progress)

MC Services Common Functionalities Enhancements:

• Enhanced MCPTT group call setup procedure with MBMS bearer
• Enhanced Location management, information and triggers
• Interconnection between 3GPP defined MC systems
• Interworking with legacy systems

MCPTT Enhancements:

• Remotely initiated MCPTT call
• Enhanced handling of MCPTT Emergency Alerts
• Enhanced Broadcast group call
• Updating pre-selected MC Service user profile
• Temporary group call - user regroup
• Functional alias identity for user and equipment
• Multiple simultaneous users

MCVideo Additions:

• Video push
• Video pull
• Private call (on-network)
• Broadcast Group Call
• Ambient Viewing Call
• Capability information sharing
• Simultaneous Sessions
• Use of MBMS transmission
• Emergency and imminent peril private communications
• Primary and Partner MC system interactions for MCVideo communications
• Remote video parameters control capabilities

MCData Additions:

• MCData specific Location
• Enhanced Status
• Accessing list of deferred communications
• Usage of MBMS
• Emergency Alert
• Data streaming
• File Distribution (FD) (off-network)
• IP connectivity

MCPTT Conformance Tests (so far only for Rel-13 MCPTT)

Timeline for MC Services and 3GPP Releases

Release 13

• Mission Critical Push to Talk (MCPTT) completed in March 2016

Release 14

• MCPTT Improvements completion 09/2017
• MCData completion 09/2017
• MCVideo completion 09/2017

Release 15 and beyond

• MCPTT Improvements completion 06/2018
• MCData completion 06/2018
• MCVideo completion 06/2018
• Railways (FRMCS) study ongoing in SA6,normative work completion ~06/2018
• Interconnection between systems study completed,normative work completion ~06/2018
• Interworking with legacy systems study completed,normative work completion ~06/2018
• Maritime communications study ongoing in SA1
• Railways (FRMCS2) study and normative work ongoing in SA1
• MBMS APIs for MC Services study ongoing in SA6 

Further Reading:

3GPP Mission Critical Specifications (selected):

Stage 1 – Requirements

• TS 22.280 - MCS Common Requirements
• TS 22.179 - MCPTT over LTE requirements
• TS 22.281 - MCVideo over LTE requirements
• TS 22.282 - MCData over LTE requirements
• TS 22.289 – Mobile Communication Systems for Railways
• TR 22.819 - Study on Maritime Communication Services over 3GPP system

Stage 2 – Functional Architecture and Procedures

• TS 23.280 – MC Common Architecture
• TS 23.379 – MCPTT Architecture and Flows
• TS 23.281 – MCVideo Architecture and Flows
• TS 23.282 – MCData Architecture and Flows
• TS 33.180 – MC Services Security aspects
• TS 23.283 – MC Interworking between LTE-based systems and non-LTE-based systems
• TR 23.790 - Study on application architecture for the Future Railway Mobile Communication System (FRMCS)

Stage 3 – Protocols

• TS 24.379 – MCPTT Call Control
• TS 24.380 – MCPTT Media Plane
• TS 24.481 – MCS Group Management
• TS 24.482 – MCS Identity Management
• TS 24.483 – MCS Management Object (MO)
• TS 24.484 – MCS Configuration Management
• TS 24.281 – MCVideo signalling protocol
• TS 24.581 – MCVideo media plane control
• TS 24.282 – MCData signalling protocol
• TS 24.582 – MCData media plane control
• TR 24.980 - Minimum requirements for support of MCPTT over the Gm

Conformance Testing (so far only for Rel-13 MCPTT)

• TS 36.579-1 Mission Critical Push To Talk (MCPTT) over LTE; Part 1: Common test environment
• TS 36.579-2 Mission Critical Push To Talk (MCPTT) over LTE; Part 2: User Equipment (UE) Protocol conformance specification
• TS 36.579-3 Mission Critical Push To Talk (MCPTT) over LTE; Part 3: MCPTT Server Application conformance specification
• TS 36.579-4 Mission Critical Push To Talk (MCPTT) over LTE; Part 4: Test Applicability and Implementation Conformance Statement (ICS) proforma specification
• TS 36.579-5 Mission Critical Push To Talk (MCPTT) over LTE; Part 5: Abstract test suite (ATS)

WBA Putting Wi-Fi in context of 5G- A detailed technical insight.

5 g networks-role-of-wi-fi-and-unlicensed-technologies-v2 from Saurabh Verma

WiFi & LTE Convergence at RAN level using 3GPP LIMONET standards.

This is in coninuation, rather to say,  to supplement  my earlier blog on WiFi offload or rightly saying WiFi & LTE convergence. putting down some excerpt from that     ......."http://blog.fundarc.co.uk/2016/09/wifi-is-much-required-to-offload-many.html"

What is of interest....

Wi-Fi is not there for hand off or to say in popular term offload. It could be leveraged as associated network. An associated data path to LTE network by converging at RAN or IP-RAN through a Local PGW and keeping the common EPC core. This convergence is possible if S1AP will be terminated at this Local PGW and MME is kept transparent to converged Local network. EPC/PGW while creating the bearer, based on IPCAN session (contains the policy), will provide the information, based on policy, which will help Local PGW to distinguish and forward the data flow.

Wi-Fi and cellular could be converged at radio access level and Wi-Fi can be used an associated data channel for the mobile access. This feasibility is well accepted now and companies like Qualcomm have more obsessed approches. Qualcomm is pursuing the aggregation at radio link level with a point of convergence at PDCP layer (https://www.qualcomm.com/invention/research/projects/lte-advanced/lte-wi-fi-interworking).

On the convergence of two at RAN, the small cell forum is also putting its attention through research and industry surveys. Its recent whitepaper, feb 2016, titled "Industry perspectives, trusted WLAN architectures and deployment considerations for integrated Small-Cell Wi-Fi (ISW) networks" SCF states at section 2.0 Integrated small cell Wi-Fi (ISW) networks..... "other interesting alternatives are possible, namely integration in the SC-APs (i.e. RAN-based integration) and/or in SC-gateways (i.e. GW-based integration). Here, the Integration function resides at the edge, possibly in an integrated ISW-AP. RAN-based integration of licensed/unlicensed access is now being addressed by 3GPP release 13, including approaches for RAN based integration of Wi-Fi and LTE.

Finally, architectures that integrate Wi-Fi and SCs at the gateway level are possible. For example, the SC-GW (i.e. H(e)NB-GW) as well as Wi-Fi GW (i.e. ePDG and/or TWAG/TWAP) may be realized together, along with associated integration functions. At the time of writing, these architectures are still in consideration and development."

So that's the future.....

This could be done at network level, where you need not to go all the way to PGW at EPC but having a local PGW at RAN/IP-RAN network. The advantage it will bring is the common EPC for both cellular and Wi-Fi networks i.e. no need for the transfer of PDN connectivity context like an inter-RAT scenarios. Only thing is that the solution is not for any kind of Wi-Fi device but it is for cellular device equipped with Wi-Fi as we need cellular for all the service control level functionality.

Service delivery is well controlled through the 3GPP PCC architecture that define PCRF, PCEF (PGW) and Application server (AS) level interaction and coordination also referred to as IPCAN session. In EPC we need bearer to carry the traffic for specific service. This bearer traffic is delivered to RAN to reach to end devices over air interfaces or radio channels. EPC provide all the necessary information as QoS parameter for specific bearer to RAN for required radio channel capacity. The interface between EPC and RAN is S1 (S1-AP for control path and S1-U for data path).

Instead of having direct interface between eNB and EPC if we keep a Local PGW node (L-PGW) to interface with EPC and provide convergence of Wi-Fi network at this L-PGW . A replica of this PCC architecture can be implemented at this L-PGW level which will decide to deliver the service at Wi-Fi of Cellular radio. This will definitely need the modification on RAN and EPC interfaces like s1AP and NAS etc. as L-PGW has to coordinate with MME.

There is nothing to scratch to get go, the provisions of such nature framework and already there with 3GPP, like for LIMONET (http://www.3gpp.org/DynaReport/WiVsSpec--500028.htm). We can leverage this for convergence of the two networks at local network level with a common core. The Standards for LIPA specific work at 3GPP (23.859) provide the data path connectivity compressed till local network, although the signaling for that remain intact like a normal PDN connectivity. This could be taken in principle for the convergence of two networks at local network level.

We believe strongly that Service provider can create yielding business case around a associated Wi-Fi network. The convergence at RAN and at network layer level would be a pure software solution with existing infrastructure and can be a ready to move solution. Other specific approaches will be requiring necessary ecosystem around for their success.

We are actively seeking the support and sponsors to extend our POC work. We need support from service provider and OEMs for widen-out our POC development. Please feel free to contact us for detail and discussion.

Note : We are strongly pursuing on our believe on next gen network with a central theme of "Homogeneous connectivity through heterogeneous networks" the solution for Wi-Fi convergence to cellular is inclined to this theme. We believe technology like MEC is going to give a master boost to our center theme.

WiFi & LTE convergence at network level using 3GPP LIMONET standards

5G - 3GPP Progress on Release15

The 3GPP standards body has forced key decisions to be made in its RAN work some three months earlier than originally planned, concerning areas where system-level features have dependency on RAN decisions. It has also agreed to develop Non-Standalone New Radio scenarios (that will use current LTE core network connectivity) in parallel with a Standalone scenario that will use the Next Generation Core.