Cellular to Wi-Fi Data Offloading

10 Apr

It’s now 18 years since the 802.11 came out by IEEE, since then the Wi-Fi had rapid developments and there are over five billion devices support Wi-Fi today around the world [1]. Since early beginnings of the year 2000, the competition of notebook, laptop and smartphone manufacturing made it essential to have a WLAN card for wireless networking, and the Wireless LANs are everywhere today in offices, hotels, homes, airports, and restaurants. The need for Wi-Fi is increasing day after day, and it became the most favorite way to be online. The Wi-Fi became a Universal technology for the modern term called “Connected Homes”, where TV and Multimedia, Home operations and automation, Life Management, and broadband connectivity are managed through the Wi-Fi.

The revolution of smartphone industry, which rose after the Apple iPhone®, had a vast spread of Wi-Fi technology along with smartphones. The 3rd Generation Partnership Project (3GPP), a collaboration between groups of telecommunications associations aims to make a globally applicable third-generation (3Gmobile phone system specification, became aware of the increasing role of Wi-Fi and started putting standards for Wi-Fi and Mobile Networks interoperability. Some mobile operators, Wireless Internet Service Providers (WISPs), and vendors saw the potential in Wi-Fi as generic and low cost wireless technology to provide their data and Internet services to millions of users through their already equipped Wi-Fi in smartphones, tablets, laptops, and PDAs.

The global mobile data traffic grew by 81 percent in 2013 [2], and nearly 18 times nearly the entire global internet traffic in the year 2000. Mobile Network Operators (MNOs) are facing increasing deployment challenges to spread their 3G and 4G sites to serve the increasing needs of customers for high speed broadband connectivity. The cost of building a new 3G/4G site is about 100 to 150 times building a Wi-Fi Access Point (AP) [3], a study by Wireless 2020shows that Wi-Fi offloading could save around 7% of total Network Deployment cost with 60% Wi-Fi coverage.  The Wi-Fi offloading became lately the most hotly debated business opportunity that provides solutions for MNOs for a lot of challenges like spectrum licensing, running costs, coverage gaps ,deployment delays, and congestion. In addition, Wi-Fi can give new business opportunities to MNOs to access new types of users like laptop, tablet, and home users. The study of Wireless 2020shows that 65% of traffic can be offloaded via already installed Wi-Fi Networks in USA. Some MNOs are thinking about building their networks using the Wi-Fi as a primary network and the mobile cellular network as a secondary network.


What is Mobile Data Offloading?

Mobile Data offloading is the use of complementary network technologies for delivering data originally targeted for cellular networks. Examples of complementary networks are the Wi-Fi and Wi-Max. With Wi-Fi Mobile Data offloading, MNOs can deliver their data services to the customers through a Wi-Fi AP connected to the core network with seamless connectivity with the cellular network. Seamless connectivity means no need for any user interaction; with many options to authenticate the user and perform the data charge payments, and make an automatic handover called “vertical handover” from the cellular network to the Wi-Fi network and vice versa. With the increased CAPEX and OPEX of applying new 3G and 4G technologies, MNOs found a great business opportunity in Wi-Fi to increase the revenue per MB by deploying APs in hotspots and cellular network coverage gaps.


How it can be done?

3GPP started defining its system to Wireless LAN interoperability in Release 6, where the cellular core network authenticate the user through 3GPP AAA server, once authentication is performed the WLAN AP allow the user to access the internet.

The authentication can be performed in multiple ways: SIM based authentication, authentication through SMS, username and password authentication, or manual authentication.

ImageFigure 1: 3GPP release 6 WLAN Access Control


Smartphone manufacturers started applying the choice in operating systems to favor either the Wi-Fi or the cellular network like Apple iOS and Android 4.0. 3GPP release 6 was the first step towards allowing Wi-Fi users to access the cellular network, but still the selections of the radio access not defined how to favor access between Wi-Fi and the cellular network; it still needs user interaction or management by an application. Another drawback is when the user switches from cellular to Wi-Fi during a download, depending on the application, the download may stop. This switching mechanism between the Wi-Fi network and the cellular network that depend on the application is called Application Based Switching as the application has to depend on its own to continue the data transfer after switching the Radio Access Technology.

In 3GPP release 8, a new approach introduced to solve the later problem and define a way for the mobile users to automatically choose between cellular and Wi-Fi networks and allowing the user to perform vertical handover between the two technologies without any application or user interaction. With the introduction of Hotspot 2.0 and Mobile IP (MIP), the 3GPP release 8 allows Wi-Fi mobility with service continuity when moving between the two technologies.

ImageFigure 2: 3GPP release 8 WLAN Seamless Mobility

Hotspot 2.0 was created by the Wi-Fi Alliance in 2012, a technology intended to render Wi-Fi technology similar to cellular technology with a suite of protocols to allow easy selection and secure authentication. It allows the mobile devices automatically select the Wi-Fi network based on its SSID. It also allows reacting some useful information such as Network and venue type, list of roaming partners, and types of authentication available.

Mobile IP allows the mobile device to have dual IPs to communicate with each access technology; with the H1 interface the Home Agent (HA) manages the mobility between the two access technologies.

The 3GPP provided further enhancement with release 10; a completely seamless Wi-Fi offloading, where the mobile device can have multiple connections to each technology managed by the 3GPP core network. Some heavy traffic like video streaming and P2P downloads can be routed via Wi-Fi and the HTTP and VoIP traffic through the cellular Network.

ImageFigure 3: 3GPP release 10 WLAN Seamless offload


Why Wi-Fi is the future potential for increased user demands?

With the increased speed of technology development today, companies like Apple, Samsung, Google, and Microsoft are changing their project schemes from yearly basis planning to quarterly basis. The market today receives a new product every quarter, the users are more demanding for high data rate applications, and the personal computing power doubles every 18 months. This creates challenges to the telecommunication vendors and cellular network operators of fast solutions to fit this increased user demands and offer economic and practical solutions to transfer from 10x speed today’s cellular data rate evolution into 1000x. The evolution of the Wi-Fi resulted in 5 generations, and reached today with IEEE 802.11ac Gigabits of speed.

ImageFigure 4: The evolution of Wi-Fi

The mobile cellular technology has 4 generations today and practically reached 100 Mbps with the LTE technology, and it is expected to reach 300 Mbps with the coming few years.

ImageFigure 5: The evolution of Mobile Cellular Speeds

Since the Wi-Fi AP is designed to cover a range of 50 meters indoor and 100 meters outdoors, repeating this coverage all over the coverage of a single cellular cell will allow the current data rate speed to jump from 10x growth into 1000x growth, providing higher spectrum efficiency and allowing application that consume much data rates like HD IPTV and the “Connected Home” approach.

ImageFigure 6: Wi-Fi + Cellular Network Integration.

 Source: Qualcomm, Wi-Fi evolution


What is the Future?

            The Wi-Fi is a great opportunity for cellular mobile operators towards deploying high efficient, low cost, high speed, and robust network. Many vendors and operators already started deploying Wi-Fi offloading solutions around the world today, and mobile country regulators are started making new laws and regulations for the spectrum by increasing the band of Wi-Fi for mobile operators to implement this technology. It can be said that it’s a new track in the mobile telecommunication evolution before the Cellular 5th Generation standard comes within the next 10 years, forcing the standard writes to consider Wi-Fi as essential part the next global telecommunication  standard.



1-      https://www.abiresearch.com/press/wi-fi-enabled-device-shipments-will-exceed-15-bill

2-      Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2013–2018

3-      ROI analysis of Wi-Fi Offloading: A Study by Wireless 2020.

4-      http://www.qualcomm.com/media/documents/files/wi-fi-evolution.pdf

Source: http://sifianbenkhalifa.wordpress.com/2014/04/09/cellular-to-wi-fi-data-offloading/


One Response to “Cellular to Wi-Fi Data Offloading”

  1. sjm786 April 10, 2014 at 9:46 am #

    Reblogged this on TELCO GLOBAL CONNECT.

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