February 18, 2015


Carrier Wi-Fi: A Cost Effective Method for Network & Bandwidth Issues

Mobile data consumption is growing exponentially with the rapid growth of smartphones/tablets and bandwidth-hungry applications (Video/Music Streaming, Rich Media Communication and personal Cloud services, etc.) that they run. Analysts predict that Wireless Data Traffic will increase by 300% in 2017, compared with what it was in 2012.

While we all enjoy the benefits (or perils) of this ubiquitous connectivity, as end users we frequently experience the issue of degrading network performance and frequent service disruption. Service Providers have historically fulfilled a higher demand through the maximum utilization of their licensed spectrum and improvised radio network equipment simply by increasing the number of base stations. Since Spectrum is a scarce resource, the limits are already stretched from that perspective. A careful analysis of the nature and longevity of peak traffic congestions/ radio resource utilization in typically crowded places like Railway Stations/ Stadiums, etc. reveal that adding more base stations is not a viable solution with the prohibitive CAPEX-OPEX costs associated with them.

One of the most novel and cost-effective approaches that have evolved to address the bandwidth and network capacity asks is to Offload data traffic to Wi-Fi and integrate it as a part of the carrier’s access network in public places with a floating population/crowd. It tremendously improves overall customer experience while reducing the Service Provider’s CAPEX-OPEX concerns. Wi-Fi offload or Carrier Wi-Fi as some call it, is now maturing to provide secure, hassle-free and higher bandwidth services to the customer.

The key challenge with Service Providers who pursue this approach, synonymously referred to as Mobile Backhaul/ Carrier Wi-Fi depending upon the Service Provider’s context, is to ensure that the Offload Implementation meets their current needs and promises to tide over future demands on their networks. There is already a vast diversity in Service Provider network components and Subscriber Mobile Phones/ Tablet devices. Solutions like Carrier Wi-Fi, which require both Network Integration as well as UE support for being fully-functional pose a huge operational threat.

Hence, it is very critical for Service Providers to perform a thorough assessment of their Wi-Fi offload solution prior to deployment. While this assessment needs to include End User Experience as a Key Performance criteria, from a Network Engineering angle it would entail interoperability testing, protocol testing and rigorous testing of scalability, security, reliability and speed. Let’s find out why.

Over the past few years, there has been tremendous efforts in standardizing the Wi-Fi offload functionality – so that we don’t end up having OEM/ Service Provider specific approaches leading to a nightmare of Interoperability problems.  At the heart of this standard effort is the Wi-Fi Offload Gateway that plugs in to the edge of any Access network (Mobile or Wireline). WOG, as I would like to call it, provides the capability to bridge traffic between the carrier’s network and the local hotspots. The innovation/ differentiation of the Network Gear OEM or a Service Provider solution lies in the manner in which WOG is architected and leveraged in the network.

For me, from an assessment point of view – key performance parameters like data throughput, reliability of the connection, latency in comparison to the native (3G/4G) wireless access, activation times (in the order of milliseconds), handover times (from/to the native network) less than 50-100 ms are of utmost importance. Apart from these, we’d typically have a Service Provider flavor of specific requirements around security aspects (Authentication, Bearer Provisioning, (U) SIM based authorization, IPSec, need for Secure Tunnels, etc.), Network discovery (e.g., adaptation of 3GPP ANDSF), and evolution of WLAN standards themselves (Hotspot 2.0 / 802.11ac etc.) that need to be assessed. While generic access is what most Service Providers would start with, solutions would also look at incorporating and managing policies that aid in providing scalability and a consistent user experience.

In my view, the following criteria would be pivotal for Service Provider strategies (and hence, to Validation SMEs like me):

  • Policy governing the Applications/ Traffic type – which could be throttled as User Experience drops (e.g., number of apps and UE per gateway, maximum number of streams per UE)
  • Handling of Voice (have/ not have VoWiFi)
  • Handover triggers and success measures – facilitating secure and clean transfer without disconnections
  • How the whole experience would be managed/guided via the Connection Manager component in the UE – how Service Providers can be assured of UE compatibility upfront
  • QoS Guarantees vs. Best Effort: Public Wi-Fi services are plagued with performance issues with no QoS guarantees. The Carrier Wi-Fi/ Offload solution should be able to distinguish itself through specific QoS SLAs

I strongly believe that the success of a Carrier Wi-Fi Offload solution lies in the quality of the validation performed. Given the matrix of User and Network gear variability coupled with Service Provider requirements, this validation becomes very crucial. Yet, it would be constrained by traditional time-to-market challenges - a specific reason why we at HCL’s ERS Practice, are pursuing an approach of putting together an Assessment Framework that could be quickly configured for a Network gear OEM/ Service Provider specific Offload solution that asks and assesses service from UE/Network perspectives.


  1. Profiting from the Rise of Wi-Fi (http://www.cisco.com/web/about/ac79/docs/sp/SP_Wi-Fi_PoV.pdf)
  2. Wi-Fi Offload Gateway (http://h21007.www2.hp.com/portal/download/product/29461/Wi-Fi%20Offload%20Gateway_1291388665285.pdf)
  3. Amdocs Wi-Fi Control Solution for Service Provider (http://www.amdocs.com/Products/network-control/wifi-control/Documents/wifi-service-provider-datasheet-v1.pdf )
  4. Placement of Wi-Fi Access Points for Efficient Wi-Fi Offloading in an Overlay Network (http://people.cs.nctu.edu.tw/~wangyc/courses/2014f-winternet/paper/hw2-wifi.pdf)
  5. MITIGATING CARRIER MOBILE TRAFFIC JAMS - White Paper (http://www.motorolasolutions.com/web/Business/_Documents/White%20Paper/_Static%20files/mitigating_carrier_mobile_traffic_jams_white_paper.pdf)
  6. Technical Considerations for Mobile Data Offload with ePDG