| Thomas Kunz | |
| Systems and Computer Engineering | |
| Carleton University | |
| http://kunz-pc.sce.carleton.ca/ | |
| tkunz@sce.carleton.ca |
| Infrastructure-less, may need to traverse multiple wireless links to reach a destination |
| Mobility causes route changes |
| Ease of deployment | |
| Speed of deployment | |
| Decreased dependence on infrastructure |
| Personal area networking | ||
| cell phone, laptop, ear phone, wrist watch | ||
| Military environments | ||
| soldiers, tanks, planes | ||
| Civilian environments | ||
| taxi cab network | ||
| meeting rooms | ||
| sports stadiums | ||
| boats, small aircraft | ||
| Emergency operations | ||
| search-and-rescue | ||
| policing and fire fighting | ||
| Wireless communication: huge field, but not mine J (I.e.: IEEE 802.11/15/16 standards, CDMA, coding and modulation) | |
| Many open research problems for TCP/IP networks, multiple IETF working groups exploring part of the problem space | |
| Dynamic topology: routing (MANET) and management (ZEROCONF) | |
| Mobility management (in particular when MANET is connected through gateway to fixed Internet): Mobile IP, SEAMOBY | |
| Transport layer: flow control for streaming services: DCCP | |
| Own research interest: routing (energy efficiency, capacity maximizing, multicast routing), QoS support, interlayer design |
| Mobile Ad Hoc Network Routing Protocols: | ||
| Limited radio transmission range and node mobility | ||
| Many Routing Protocols (literally 100s): | ||
| On-demand: AODV, DSR | ||
| Pro-Active: OLSR | ||
| Hybrid: ZRP | ||
| Problems: | ||
| Most existing performance comparisons based on ideal propagation model (free space model, two-ray ground model) | ||
| Our simulation results with shadowing model show severe performance degradation | ||
| Question: does physical layer impact performance of routing protocols and if so, what to do about it? | ||
| Ideal Models | ||
| Free space model and two-ray ground reflection model | ||
| Shadowing Model | ||
| b: loss exponent, corresponding to mean transmission range | ||
| s:shadowing deviation | ||
| Signal strength fluctuates in shadowing model | ||
| Ideal model (left) and shadowing model (right) over the same distance between two nodes | ||
| Fluctuation at least 2 orders of magnitude | ||
| Signal strength fluctuation causes active links to “break” | ||
| Simulations of AODV & DSR show that | ||
| Packet Delivery Ratio (PDR) decreases significantly | ||
| Broken links introduce more Route Discovery processes | ||
| Cause more control messages and longer packet delay | ||
| Performance Comparisons with different b values |
QoS Routing: Find Routes satisfying QoS constraints
| Link state metrics should be available and manageable | |
| Link quality changes quickly and continuously due to node movement and surrounding changes | |
| Computational cost and protocol overhead affect the performance of the QoS routing protocol | |
| Protocol performance evaluation is complex |
| Advantages | |
| suitable for the unpredictable nature of Ad-Hoc networks | |
| suitable for the requirement of quick reaction to QoS demands | |
| makes call admission control possible | |
| avoids the waste of network resources | |
| Disadvantages | |
| introduces additional protocol overhead | |
| trade-off between the QoS performance and traditional protocol performance |
| Selects MPR to cover 2-hop neighbors | |
| Exchanges neighbor/MPR information in Hello message | |
| Generates and relays TC message to broadcast topology information | |
| Reduces control overhead by limiting MPR set | |
| In the graph, B selects C as MPR |
| OLSR protocol does not guarantee to find the best bandwidth route | |
| Three heuristics are proposed to enhance OLSR in bandwidth aspect | |
| The heuristics select good bandwidth neighbor as MPR | |
| Based on evaluation in static network scenarios, heuristic 2 is chosen: best-bandwidth neighbours are selected as MPRs until 2-hop neighbourhood is covered | |
| In the previous network topology, B selects A,F as MPRs |
| Outperforms the original OLSR protocol in bandwidth aspect (i.e., finds better bandwidth routes) | |
| More MPRs are selected; more TC messages are generated and relayed | |
| The additional control messages increase the MANET network load | |
| The overlap of 2-hop neighbors covered by MPRs causes TC collision |
Next Steps: Build Wireless MESH with QoS Support (joint project with NCIT and CRC)
| Mesh nodes: special hardware based on Intel IXP 425 NPU (ZAP nodes) | |
| Wireless Links: 802.11a/b/g, future support for 802.16a | |
| Software: Routing between ZAP nodes based on OLSR (CRC code) | |
| My research group: QoS support at MAC, routing, and end-to-end layer | |
| Related project (i.e., shared platform) at U of O with Prof. Makrakis |