A Practical Traffic Management System for Integrated LTE-WiFi Networks Zhuoran Li 11/4/2015.
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Transcript of A Practical Traffic Management System for Integrated LTE-WiFi Networks Zhuoran Li 11/4/2015.
![Page 1: A Practical Traffic Management System for Integrated LTE-WiFi Networks Zhuoran Li 11/4/2015.](https://reader036.fdocuments.us/reader036/viewer/2022062409/5697bf8d1a28abf838c8c847/html5/thumbnails/1.jpg)
A Practical Traffic Management System for Integrated
LTE-WiFi Networks
Zhuoran Li11/4/2015
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Overview
• Problem:– With the data traffic increasing fast, operators
start to deploy Wi-Fi for additional capacity, therefore how to manage the network interface for user flows is important.
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Drawbacks of current solution
• Naïve policies: in most cases, the connection managers are on the user device. (User decides to connect to WiFi AP or basestation.)
• Static decision: interface selection isn’t adaptive to dynamic conditions of wireless networks.
• Coarse-grained policies: interface selections based on the user-level. However, application-level based selection will be better.
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Their Idea: ATOM
LTE Core-Network
WiFi Gateway
Traffic Manager
Maps user flows to appropriate network(LTE/WiFi) Centralized management -> Efficient use of network
resources Reduces backhaul costs -> Facilitates dynamic traffic
mgmt Operates for each LTE cell -> Scalable Standards agnostic -> Easily Deployable
PDN-gateway
MME
Serving-gateway
Network Interface
Assignment
Switching Service
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Components Network Interface Assignment Algorithm
(NIA)– Goal: Dynamically maps user traffic flows to
appropriate LTE basestation or WiFi AP
• Interface switching service (ISS)– Goal: Switch current user flows from WiFi AP to
LTE or vice versa based on decisions from NIA
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Component 1: NIA
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Consider an LTE cell and multiple WiFi APs in its coverage area
• Assign basestation/ AP to each flow– Maximize sum of users flows’ QoE
• QoE captured using “utility”– Weighted PF provides differential QoE
• Pricing function supports 2 models– Based on data usage– Based on price/byte
Problem Formulation
7
k
max kU
())1log( PtwU kk
Weight Throughput Network Pricing
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Network Interface Assignment (NIA)
• Problem is NP-Hard– Including the simplest topology of an LTE cell and a WiFi AP
• NIA is a two-step greedy heuristic– Considers each AP-basestation in isolation– Fixes assignment for AP that maximized incremental utility– Iterate till all hotspots are covered– Complexity is O(B2N), where N = # flows, B = # APs
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NIA algorithm
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Component 2: Interface Switching Service
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Interface Switching Service (ISS)
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ISS
• They focus on the HTTP-based traffic flows.– HTTP-based downloads: go through core-network,
connecting with the HTTP Proxy in the Core-Network.
– HTTP-based video streaming and browsing: for this traffic, they design it go directly to the Internet.
– Non HTTP-traffic: go through the core network.
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Evaluation
In WiFi AP1, 4 users steamYouTube videos of average bit-rate 1.5 Mbps while 1 user downloads a large-file. In WiFi AP2, 2 users stream YouTube videos of average bit-rate 1.5 Mbps while 2 users download large-files. Both the LTE users stream YouTube videos of average bit-rate 1.5 Mbps. We compare the throughput of WiFi users for the case with and without ATOM (NO-ATOM).
With ATOM, User #3 and user #6 are moved to LTE-basestation.
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Evaluation
There are 4 users streaming YouTube videos of average bit-rate of 1.5 Mbps. Users#1, 2 and 3 are within WiFi coverage while User#4 can only access the eNodeB. We introduce 2WiFi users with background traffic at around 30 seconds into the experiment such that the flows are active for about 40 seconds
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Benchmarking the ISSMeasured the time taken for flows to switch using ISS:
• HTTP based video streaming flows• Hulu (uses HTTP-DASH) v/s Youtube(uses HTTP-PD)
Insight: Switching time improves with DASH streaming• DASH flows use smaller chunk sizes to ensure adaptive-ness
to changing network conditions
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My understanding
• Pros:– The most important contribution of this work is
that they build a real system. For interface selection, a lot of searcher provides a lot of algorithm, however, this is the first one to build the real system.
– To verify their system, they build a small testbed and also did a large-scale simulation. The combination of real testbed and simulation can convince people about their system.
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My understanding
• My questions:– Is that possible for a mobile device to send data
though both cellular and wifi? If that is possible, why a user have to choose one interface not transferred at both?
– They didn’t say clearly if they make the HTTP-based video streaming go directly to the Internet, how the charge this data?
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Thanks!