Overview of Mobile Wireless Communication Student Presentations and Research Papers National Wireless Communications Technology Roadmap Trends in Communications and Media Technology, Applications and Use Evolution of Mobile Wireless Communication Networks: 1G to 4G Mobile & Wireless Communication Technologies & Techniques Improvements in WiFi eMobility Strategic Research Agenda

Network (IP) + Application Layer Modification: Virtual WiFi + WiFiProfiler A Case Study

MultiNet: Connecting to Multiple IEEE Networks Using a Single Wireless Card  There are a number of scenarios where it is desirable to have a wireless device connect to multiple networks simultaneously.  Currently, this is possible only by using multiple wireless network cards in the device.  Unfortunately, using multiple wireless cards causes excessive energy drain and consequent reduction of lifetime in battery operated devices.  Microsoft Research’s MultiNet facilitates simultaneous connections to multiple networks by virtualizing a single wireless card.  The wireless card is virtualized by introducing an intermediate layer below IP, which continuously switches the card across multiple networks.  The goal of the switching algorithm is to be transparent to the user who sees his machine as being connected to multiple networks.  VirtualWiFi is transparent for the upper layer protocols, and works well over popular IEEE wireless LAN cards.

Motivation behind MultiNet  The MultiNet virtualization architecture enables several new applications that were earlier not possible using a single wireless card e.g.:  Concurrent Connectivity:  A user can connect her machine to an ad hoc network, while staying on her authorized infrastructure network.  For example, consider the case where Kisco’s employees conduct a business meeting with Macrosoft’s employees at Macrosoft’s headquarters.  With MultiNet and a single wireless network card, Kisco employees can share documents, presentations, and data with Macrosoft’s employees over an ad hoc network.  Macrosoft’s employees can stay connected to their internal network via the access point infrastructure while sharing electronic information with Kisco’s employees.  Macrosoft does not have to give Kisco employees access in their internal network in order for the two parties to communicate.

Motivation behind MultiNet  Network Elasticity:  The range of an infrastructure network can be extended by allowing border nodes to act as relays for authorized nodes that are outside the range of the Access Point (AP).  For example, a node X, associated to a home AP, is being used to browse the web.  Another node Y is moving while connected to the same AP and looses its connection because it goes out of range.  With MultiNet, if X is within range of Y, it can connect to Y over an ad hoc network, and forward Y’s traffic on to the AP.

Motivation behind MultiNet  Gateway Node:  A node that is part of a wireless ad hoc network and close to an AP, connected to the Internet, can become a gateway node for the ad hoc network.  This node becomes a bridge for other nodes on the ad hoc network, passing their packets to and from the Internet.

Motivation behind MultiNet  Network Security:  Different groups (e.g. human resources personnel, secretaries, developers etc.) within a company may be given different permissions to access data servers.  These servers could be on physically different networks.  For a privileged user, who has permission to access different networks, having MultiNet is valuable.  S/he would not have to disconnect and reconnect between networks every time s/he wishes to access resources on different networks.

Motivation behind MultiNet  Increased Capacity:  The capacity of ad hoc networks can be increased when nodes within interference range can communicate by switching on orthogonal channels.  Virtual Machines:  Users can connect different virtual machines, to physically different wireless networks.

MultiNet Architecture

MultiNet Implementation

Virtual WiFi related Publications  "A Virtualization Architecture for Wireless Network Cards" Ranveer Chandra PhD Thesis, Cornell University, September  "MultiNet: Connecting to Multiple IEEE Networks Using a Single Wireless Card" Ranveer Chandra, Paramvir Bahl and Pradeep Bahl Proceedings of IEEE Infocom 2004, Hong Kong, March 7-11, Infocom Presentation "MultiNet: Connecting to Multiple IEEE Networks Using a Single Wireless Card" Infocom Presentation  MultiNet: Enabling Simultaneous Connections to Multiple Wireless Networks Using a Single Radio Ranveer Chandra, Paramvir Bahl and Pradeep Bahl Demo and Poster in ACM/USENIX MobiSys, San Francisco, May 5-8, 2003 Poster in Mesh Networking Summit, Snoqualmie, WA, June 23-24, 2004 MultiNet: Enabling Simultaneous Connections to Multiple Wireless Networks Using a Single Radio  MultiNet: Enabling Simultaneous Connections to Multiple Wireless Networks Using a Single Radio Paramvir Bahl, Pradeep Bahl and Ranveer Chandra Microsoft Tech Report, MSR-TR , June 2003 MultiNet: Enabling Simultaneous Connections to Multiple Wireless Networks Using a Single Radio

Virtual WiFi Applications related Publications  "Architecture and Techniques for Diagnosing Faults in IEEE Infrastructure Networks" Atul Adya, Paramvir Bahl, Ranveer Chandra and Lili Qiu Proceedings of ACM Mobicom, Philadelphia, September 26-30, "Architecture and Techniques for Diagnosing Faults in IEEE Infrastructure Networks"  "SSCH: Improving the Capacity of IEEE Multihop Networks Using Slotted Seeded Channel Hopping" Paramvir Bahl, Ranveer Chandra and John Dunagan Poster in Mesh Networking Summit, Snoqualmie, WA, June 23-24, 2004 "SSCH: Improving the Capacity of IEEE Multihop Networks Using Slotted Seeded Channel Hopping"  "SSCH: Slotted Seeded Channel Hopping for Capacity Improvement in IEEE Ad-Hoc Wireless Networks" Paramvir Bahl, Ranveer Chandra and John Dunagan Proceedings of ACM Mobicom, Philadelphia, September 26-30, Mobicom Presentation "SSCH: Slotted Seeded Channel Hopping for Capacity Improvement in IEEE Ad-Hoc Wireless Networks" Mobicom Presentation  "WiFiProfiler: Cooperative Fault Diagnosis in Wireless LANs" Ranveer Chandra, Venkata N. Padmanabhan and Ming Zhang Proceedings of ACM/USENIX MobiSys, Uppsala, Sweden, June 19-22, MobiSys Presentation "WiFiProfiler: Cooperative Fault Diagnosis in Wireless LANs" MobiSys Presentation  "Opportunistic Use of Client Repeaters to Improve Performance of WLANs" Paramvir Bahl, Ranveer Chandra, Patrick P. C. Lee, Vishal Misra, Jitendra Padhye, Dan Rubenstein and Yan Yu Proceedings of ACM CoNEXT, Madrid, Spain, December 9-12, "Opportunistic Use of Client Repeaters to Improve Performance of WLANs"

Virtual WiFi Download URL  53d1-4dba-a9d8-8ba1dcccead7/ 53d1-4dba-a9d8-8ba1dcccead7/  > 12 MB in size

Microsoft Research

WiFi Hardware IHV Miniport Driver (ExtSTA, NetMon, ExtAP) NDIS Port 1 VWiFi Filter Driver VWiFi Bus Driver VWiFi Miniport Driver NDIS Port 0 NWiFi Filter Driver VWiFi Filter Driver Networking Stack Primary Adapter Secondary Adapter Networking Stack WLAN Service PrivateInterfaceLegend:Control Data Control & Data Netsh Provided by: Microsoft ISV IHV OEM WCN ISV App IHV App OEM App Hosted Network APIs User Mode Kernel Mode

// open handle dwError = WlanOpenHandle( WLAN_API_VERSION_2_0, NULL, &dwNegotiatedVersion, &hClientHandle); // check return value // configure softap dwError = WlanHostedNetworkInitSettings( hClientHandle, &FailReason, NULL ); // check return value // start softap dwError = WlanHostedNetworkStartUsing( hClientHandle, &FailReason, NULL ) ; // check return value // use softap // stop softap dwError = WlanHostedNetworkStopUsing( hClientHandle, &FailReason, NULL ) ; // check return value // close handle dwError = WlanCloseHandle(hClientHandle, NULL);

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WiFiProfiler: Cooperative Diagnosis in Wireless LANs Microsoft Research

Wireless Woes  Users often wonder why:  “My machine says: wireless connection unavailable”  “I get poor performance on wireless”  “My wireless card keeps trying to authenticate”  “Is it just me?”

Wireless Woes  Users often wonder why:  “My machine says: wireless connection unavailable”  “I get poor performance on wireless”  “My wireless card keeps trying to authenticate”  “Is it just me?”  Many places have no/minimal network admin  Hotspots: cafes, airports  Transient networks: conferences, IETF meetings

Prior Work: Operator View  Infrastructure-based monitoring (Aruba, DAIR)  Focuses on operator perspective (e.g., rogue APs)  Monitoring at clients (e.g., [Adya 2004])  Fault diagnosis using infrastructure support  Also focuses on operator perspective  Correlate client observations at AP (MOJO)  Detect PHY level anomalies

WiFiProfiler Goal: User View Enable clients to diagnose network failures without requiring admin/infrastructure support:  Reduce user frustration  Reduce load on admin, when there is one Help users help themselves

State of the Art: Local Diagnosis Wireless Connection Manager, WZC Reasonable detection, Poor diagnosis Cannot Associate MAC Filtering Bad AP Bad WEP Key Bad NIC

WiFiProfiler  Based on two key observations:  Clients form Information Plane with peers  Even when client cannot connect to AP  Extent of problem indicates cause Diagnose faults by correlating peers’ health

WiFiProfiler Overview Create Information Plane Dissatisfied Machine (Cannot connect to WEP-enabled AP) Req. Health Health Info. (WEP key info) Diagnose Problem: Same WEP key? Access Point Healthy Client Health Info. (WEP key info) Healthy Client Diagnose range of problems across layers!

Faults and Some Causes No IP Address Security H/w or s/w DHCP Server No Association No AP Detected Location WAN congestion Wireless problem Poor Performance End-to-End Failure Firewall/proxy WAN Disconnect

WiFiProfiler Design Goals  Transparency:  Minimal user impact/involvement  Deployability:  Work with off-the-shelf cards and unmodified drivers  Scalability:  Work with a large number of clients  Security:  Prevent compromise of clients and AP

WiFiProfiler Architecture  Sensing: What is monitored?  Communication: How is it shared?  Diagnosis: How are faults diagnosed?

Sensing  Monitor health of client’s connectivity  Static info (e.g., NIC type)  Dynamic info (e.g., assoc. success/failure) H/w or s/w No Association Fault Some Causes Sensed Info NIC Model, Make, Driver version Auth/Encryption setting, key info Security

Sensed Information  User-level service (daemon) polls various layers  Wireless: NIC, BSSID, RSSI, Beacon Loss, 1-way hash of key, Interface Queue  IP: IP Address, DHCP, DNS  Transport: Failed connections, Server Ports  Application: Web proxy settings  Snapshot obtained once every second  Summarized information < 1200 bytes

Communication NICs can connect to only one network at a time Challenges:  Discovery: How does H know that D needs help?  Parallelism: How does H send packets to D? Req. Health Sensed Info D H Establishing the Information Plane

Discovery  D initiates ad hoc network with distinct SSID  Special SSID format denotes request for help  H receives beacon even when associated to AP D Port: 5000 SSID: Help: :5000 H

VirtualWiFi Layer Virtual Interface 3 TCP/IP, Network Stack Virtual Interface 2 Application Layer User-level Kernel-level Approach: Virtualize card, buffer packets, switch b/w networks Virtual Interface 1 Wireless Card Parallelism using VirtualWiFi

Communication Protocol  WiFiProfiler uses 2 (virtual) adapters:  Primary adapter activated in normal use  Helper adapter dedicated for WiFiProfiler  Activated only when needed D H Port: 5000 SSID: Help: :5000 Primary VNIC Helper VNIC

Diagnosis  Initiated by user  Correlate peers’ info and infer likely cause  Rule-based techniques instead of black-box  Suggest steps for problem resolution  Change configuration settings  e.g. local DNS server, web proxy, WEP key  Change location, contact admin  Diagnose faults across layers of network stack

NOYES Diagnosing Association Failure Is Sec. config Same? Bad Sec. setting (Fix it) NO Low Signal Level? Bad signal (change location) Similar card Associated? YES If another peer has successfully associated with the AP: YES MAC Filtering (contact admin) NO S/w or H/w config (change NIC or update driver)

Diagnosis Features  Inherent uncertainty in some cases  Need info from AP to confirm MAC filtering  Conflicting info from peers  Used to eliminate branches in diagnosis procedure, e.g. NIC type  Vulnerability to bogus info from attackers  Use information from large number of peers  Susceptible to Sybil attack

Evaluation  Sensing: Low overhead  (used < 1% CPU on 1.33 GHz laptop)  Communication using VirtualWiFi:  Healthy clients spend < 2 sec sending info  Sick clients get information within 30 seconds  Much of the delay in discovery (scanning delays)

Little Impact on Healthy Clients Extra 0.5 to 3 seconds!

Effectiveness of WiFiProfiler Relevant diagnosis at all clients within 30 seconds!

WiFiProfiler Summary  Enables cooperative diagnosis in WLANs  Without infrastructure support, low overhead  Working system on Windows XP  Future work:  Security: Privacy, Sybil Attacks, Passive Mode  Long-term Profiling

 INNOVATIVE TECHNOLOGY (Beam Forming etc.)  7363 Mesh APs already deployed in UET Taxila Boys Hostels with Zone Director 3000 Centralized Management Hardware  In the process of procuring more 7363s and 7372s for Library, Hostels, Multi-purpose Hall and other buildings. CASE STUDY: RUCKUS WIRELESS