Redefining Connectivity with LTE – WiFi Interworking

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We go through the following topics:
1) Need for Cellular WiFi Interworking.

2) What is LTE – WiFi Interworking?
3) How can Seamless Integration of LTE and WiFi be achieved?

4) What are the Business Benefits of LTE-WiFi Interworking?

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At a time when end customers look for high-speed data to power their new-age device form factors, operators look for cost-effective methodologies to enable this growing thirst for data and also put efforts to ease out pressure from their networks. This data-intensive challenge can successfully be met by innovating on delivering connectivity to the users by intertwining next-generation cellular technologies such as LTE with WiFi and deliver carrier-grade WiFi coverage regions that can offload the operator traffic in a cost-efficient manner. Internet Protocol or IP is the underlying fabric upon which networks are built and IP defines the structure of information packets and most importantly, it also defines how they are transported between two end-to-end IP devices across an interconnection of networks. Driven by global standards, IP protocols are designed to be agnostic to the underlying characteristics of any of the intervening networks and have provided the highway architecture for the modern internet today. And owing to these technology-agnostic characteristics of IP, it has become a natural choice of selection for interworking Cellular and WiFi Networks, since It is a common language that is supported by both the networks and seamlessly integrates the both to deliver best in class carrier-grade WiFi capability that can deliver exactly what users need and where they need it. The world over, including in India, operators are fast realising the full potential of WiFi and as a result, today, Cellular WiFi Integration is seen as a technique that can smartly manage difficult data traffic scenarios in a mobile operator network. And hence, in such a situation, a successful amalgamation of WiFi and Cellular technologies such as LTE can dynamically route data to use the optimal radio interface that is just ideal for particular data applications at the user end. The best part of this technology integration is the fact that at the end-user level, nothing changes, while at the operator level cellular network handshake of WiFi ensures a considerable reduction of stress on the operator’s backhaul as well as optimal usage of network resources such as spectrum. As there is an upsurge in the usage of mobile devices such as iPhones, tablets and phablets, delivering the right user experience is becoming increasingly important for operators as consumers expect to receive the same quality of service whether they use WiFi, 3G or LTE. But at the operator level, as an intertwining technology, WiFi must provide operators with the right tools to manage WiFi networks in a similar fashion that operators are used to operating and maintaining their existing 3G or LTE networks, and hence delivery of carrier-grade WiFi solutions becomes important. In a 4G scenario where operators are looking at incorporating the best possible LTE strategies, WiFi is an intertwining technology that can very well integrate the trusted and untrusted WiFi networks with the operator’s packet core and this way operators can provide a seamless integration of their mobile and WiFi access. 

What is LTE – WiFi Interworking?


LTE – WiFi interworking is a methodology that can enable an operator to offload their LTE driven subscriber data requirement onto a WiFi Access network and still be able to control LTE packet core infrastructure for subscriber Authentication, Policy and Charging functions. While operators device strategy to interlink LTE and WiFi, authentication of the end-user is surely a very critical aspect for any network and that is why operators need a converged AAA that supports DIAMETER based EAP authentication along with RADIUS-based authentication for RADIUS supportive networks like WiFi. And this is where STL can provide a much-needed boost for operators WiFi strategy. 

How can Seamless Integration of LTE and WiFi be achieved?


STL has an advanced AAA known as Evolved 3GPP AAA compliant to industry standards of 3GPP which plays an important role in LTE interworking with WiFi. Converting challenges into opportunities for operators, this compliant by STL can support diameter based EAP Authentication required for integration with LTE type of network or where Access network is on DIAMETER as well as authentication for RADIUS supportive networks like WiFi. And hence this can enable a platform on which LTE and WiFi interworking can be established in a seamless manner. STL’s Evolved 3GPP AAA also holds functionalities that can provide the Wx interface support for HSS authentication over the LTE network. It is capable to provide support for 3GPP standard-compliant SWa interface for EAP authentication with HSS as well as capable to support SWm – for additional Authentication parameters based on subscriber profile, authorization information update, ePDG initiated session termination and S2b interface support towards PGW over GTP or PMIPv6 tunnelling. It will also provide support for S6b interface between 3GPP evolved AAA and P-GW for tunnelling authentication.

What are the Business Benefits of LTE-WiFi Interworking?

  • LTE- WiFi Interworking allows the operator to provide the same set of services that are already available in the existing LTE network – Product plans
  • Operators can use WiFi as alternate technology to LTE where LTE radio coverage is weak or the cost of coverage is higher compare to WiFi
  • LTE- WiFi Interworking allows the operator to grow their network into rural/distant areas and save on transport and OPEX cost
  • Allows Operator launch bundled services – with WiFi
  • With packet core network integration an operator can enable improved visibility and control over WiFi traffic and gain enhanced customer experience.
  • Furthermore, users are able to reach their LTE services via both mobile and WiFi access. This makes WiFi a truly integral part of mobile broadband access.
  • It enables even closer control over traffic with seamless network-controlled handovers between radio and WiFi even during roaming.
  • Session continuity assures that applications are not affected when the user device moves between different WiFi networks as the same IP address is preserved


Frequently Asked Questions

1. What is a LTE network?

LTE or commonly known as long-term evolution is a global open interoperable standard for wireless high-speed cellular data and is the technology behind today’s 4G cellular networks. LTE provides high-speed mobile broadband data, telephone services like VoLTE ie Voice over LTE, Multimedia video support, public safety functions such as secure database access, computer-aided design, mapping, remote management systems, and non-mission critical push to talk service. This standard is developed by the 3rd Generation Partnership Project (3GPP).

An LTE network has four major components: Core Network (Often called the brain of the subsystem, it consists of gateways and servers that control access, quality of service, billing, and network policies), Radio Access Network (These are the cell sites/towers and consists of transceiver equipment eNodeB and antennas that provides wireless coverage to the device), backhaul network(It consists of fibre & microwave connections and it connects the radio access network to the core network), User Equipment (It consists of mobile devices, routers etc. and it helps connect directly to the radio access network).

Four major features of LTE are:

a) Exclusive Spectrum – Better spectrum allocation with the division between commercial and mission-critical services

b) High Speed – LTE networks are typically designed with three sectors on each site and each sector supports the same amount of data. Each sector usually supports 40Mbps of data.

c) Priority and Preemption – It allows the network operator to make sure that the most important traffic always gets allocated to the priority user even if the network gets busy.

d) Self Organising Networks (SON) – It allows the network to automatically self-heal itself during outages ie temporarily one cell site can compensate for the non-functional site avoiding a communication blackout. This allows the users in the sector to access the service but the throughput may vary because more users get added to the specific sector.

2. What is WiFi?

Put simply, WiFi is a technology that uses radio waves to create a wireless network through which devices like mobile phones, computers, printers, etc., connect to the internet. A wireless router is needed to establish a WiFi hotspot that people in its vicinity may use to access internet services. You’re sure to have encountered such a WiFi hotspot in houses, offices, restaurants, etc.

To get a little more technical, WiFi works by enabling a Wireless Local Area Network or WLAN that allows devices connected to it to exchange signals with the internet via a router. The frequencies of these signals are either 2.4 GHz or 5 GHz bandwidths. These frequencies are much higher than those transmitted to or by radios, mobile phones, and televisions since WiFi signals need to carry significantly higher amounts of data. The networking standards are variants of 802.11, of which there are several (802.11a, 802.11b, 801.11g, etc.).

3. What is backhaul?

Backhaul is a transport network that connects the core network (routes data in various sub-networks) and access network (connects end devices to the network). Backhaul can be wired (via optical fibre cable/copper cable/ coaxial cable/ethernet cable) or wireless (via Free space optics (FSO)/Point to Point microwave radio transmission such as terrestrial or satellite/ Point to Multipoint microwave radio transmission such as LDMS, WiFi, WiMAX). Wireless backhaul offers cost efficiency, ease of deployment and high capacity. On the other hand, Wireline backhaul offers endless capacity, better life span, reliability but require significant investment on the network deployment side. 

Use cases of Backhaul:

a) Mobile Backhaul: As more users keep coming online and data-heavy applications increase in number, the global mobile data traffic is going up. This demands broader network coverage and larger capacity/bandwidth. To address these challenges service providers have to either put more macro towers or increase spectrum spaces or develop newer technologies such as LTE/LTE-A to utilise the spectrum more efficiently, all of which is capital intensive. Another inexpensive solution is mobile backhaul which essentially is low powered small towers with lesser footprint for catering to the user and their needs more efficiently. These small cells can be Femto (indoor cell for the residential area; 10m to 1km) / Pico (indoor cell for small businesses; range 200m) / Micro (for rural areas; range 35kms) / Metro (for urban areas; less than 100m) for extending macrocell service.

b) Private Networks: On-premise networks that are owned privately have dramatically enabled organisations to transition from expensive legacy based voice-only networks to media and applications serving networks. With high user density and data demand, wireless backhaul networks like LTE (pico/femto cells) work best for such environments. 

c) Critical Infrastructure Networks: Such networks demand communications to be secure and available at all times with ultra-low latency. Existing mission-critical networks like TETRA, Tetrapol, etc. are voice-centric and going forward to serve the needs the future will be around 4G/5G technologies. To deliver high-performing applications like real-time video, high-resolution imagery, multimedia messaging, situational awareness etc. backhaul support will be a must.

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