Dynamic Load Balancing and Channel Allocation in Indoor WLAN

1. Dynamic Load Balancing and Channel Allocation in Indoor WLAN Mohamad Haidar Committee : Dr. Hussain Al-Rizzo Dr. Robert Akl Dr. Haydar Al-Shukri Dr. Yupo Chan Dr. Hassan Elsalloukh Dr. Seshadri Mohan

2. Proposal Outline • Background • Problem Statement • Review of Literature • Research Objectives • Project Plan • Conclusion • References • Questions Dissertation Proposal

3. Background • What is WLAN? • Flexible data communications system • Consists of one or more wireless devices • WLAN uses IEEE 802.11 standard • Two types of WLAN: • Ad-Hoc: Two or more PCs equipped with wireless adapter cards, NO connection to a wired network. • Client/Server: Multiple wireless devices linked to a central hub (AP) which act as a bridge to the network resources. Dissertation Proposal

4. Background(continued) • Family of WLAN: • 802.11: 1-2 Mbps in the 2.4 GHz band (FHSS or DSSS) • 802.11a: Extension to 802.11 provides up to 54 Mbps in the 5 GHz band (OFDM) • 802.11b (Wi-Fi): extension of 802.11 provides 11 Mbps with a fall back to 5.5, 2, and 1 Mbps in the 2.4 GHz. (DSSS) • 802.11g: offers transmission of 20-54 Mbps over relatively short distances in the 2.4 GHz.(OFDM) • 802.11n: build on MIMO offers high throughput of 100-200 Mbps Dissertation Proposal

5. Problem Statement • Dynamically balance traffic load on APs and minimize channel interferences by assigning optimal channels (non-overlapping) to the APs on an indoor WLAN. • Interferences: Co-channel Adjacent Dissertation Proposal

6. Literature Review • Cellular networks review: • ILP optimization was used on selecting optimal position of BSs in a cellular network [1]. • Divide and conquer is another optimization technique was used to position BSs [2]. • Dynamic load balancing (channels) was applied in cellular networks to reduce call blocking probability [3]. • WLAN review: • Static • AP placement and channel assignment was proposed in [4] and [5] using an optimal ILP. • Provides best set of AP locations for load balancing • Constant BW is provided by a channel at an AP regardless of the number of users Dissertation Proposal

7. Literature Review (continued) • WLAN review: • Dynamic • Dynamic load balancing wasONLY considered by [8]. But did NOT provide reconfiguration of channels. • Only proposed an approach to minimize traffic disruption caused by association or dissociation of new nodes to and from their respective APs. • Other related work: • Moving objects, such as people affect the performance of the system by introducing large variations in the received signal strength [9]. Dissertation Proposal

8. Literature Review (continued) • Other Related work: • Without proper consideration of cell locations and cell sizes, deployment of high-density WLANS might carry significant risk of poor performance. WHY? Dissertation Proposal

9. Research Objectives • Optimize AP selection and traffic allocation • Formulate AP placement according to initial traffic • Optimize dynamic channel allocation • Formulate a dynamic optimal channel assignment by min. interference between adjacent and co-channel APs. Dissertation Proposal

10. Research Objectives (continued) • Interference by adjacent and co-channel cells should be minimized. • A node is considered to be covered by an AP if power received from its corresponding AP exceeds a certain threshold value. • User distribution traffic load will be treated as a statistical Poisson distribution (varying traffic with time). • Propagation mechanisms will be taken into consideration: • For optimal performance of the whole network, a centralized decision-making algorithm will be implemented. Dissertation Proposal

11. Research Objective (continued) • Formulation • Objective: • Minimize congestion at bottleneck APs: max{C1, C2, …, CM}, (1) Where i is the number of APs, j is the number of candidate APs and Ci is the congestion factor at AP i. • The objective function is subject to the following constraints (2) Where xijis a binary variable takes the value of 1 whendemand cluster i is assigned to AP j and 0 otherwise. for j=1,…,M (3) Where Bjis the maximum bandwidth of AP j, Ti is the average traffic load at demand cluster i. • Dynamic feature will add the time constraint on these equations! Dissertation Proposal

12. Project Plan • Phase I: • Has been started and in progress • Some simulations have been conducted using available software packages • Optimization and Network flow class with Dr. Yupo Chan • Realistic indoor environments will aid in formulating optimization problem Indoor floor plan using different wall materials, door way and Tx. Dissertation Proposal

13. Project Plan (continued) • Phase II: • Formulating the optimization problem • Apply the formulated problem to realistic environments • Phase III: • Dynamic optimization feature will be added. • Mobility model will be presented in terms of Poisson distribution • Several simulations will be carried out under different scenarios and constraints. • Results will be presented and compared to models reported in [4] and [5]. Dissertation Proposal

14. Conclusion • It is expected that the proposed dynamic traffic load-balancing scheme will lead to an effective utilization of the channel and an improvement in capacity and coverage area of WLAN. • Unlike other schemes this dynamic feature will strive to give the optimal performance as time progresses. Dissertation Proposal

15. References • C. Glaber, S. Reith, and H. Vollmer. “The Complexity of Base Station positioning in Cellular Networks.” Workshop on Approximation and Randomized Algorithm in Communications Networks, March 2000. • E. Yammaz and O. K. Tonguz. “Dynamic Load Balancing Performance in Cellular Networks with Multiple Traffic Types.” IEEE Vehicular Technology Conference, pages 3491-3495, September 2004 • S. Gordon and A. Dadej. “Design of High Capacity Wireless LANs based on 802.11b Technology.” 6th International Symposium on Communications Interworking, pages 133-144, October 13-16, 2002. • R. Akl and S. Park. “Optimal Access Point selection and Traffic Allocation in IEEE 802.11 Networks,” Proceedings of 9th World Multiconference on Systemics, Cybernetics and Informatics (WMSCI 2005): Communication and Network Systems, Technologies and Applications, paper no. S464ID, July 2005 • Y. Lee, K. Kim, and Y. Choi. Optimization of AP placement and channel assignment in wireless LANs. LCN 2002. 27th Annual IEEE Conference on Local Computer Networks, pages 831-836, November 2002. • M. Klepal, R. Mathur, A. McGibney, and D. Pesch. “Influence of People Shadowing on Optimal Deployment of WLAN Access Points.” IEEE Vehicular Technology Conference, pages 4516-4520, 2004. • S. Gordon and A. Dadej. “Design of High Capacity Wireless LANs based on 802.11b Technology.” 6th International Symposium on Communications Interworking, pages 133-144, October 13-16, 2002. Dissertation Proposal

16. Questions? Dissertation Proposal