Towards Reducing Handoff Time in Next Generation Wireless Networks

The handoff process in WiFi networks has a very important role to provide continuity of the service to wireless users where the access points (APs) are in numerous numbers. In traditional WiFi networks, the handoff process takes a few seconds and is initiated by the wireless devices, but these few s

Project Title

Towards Reducing Handoff Time in Next Generation Wireless Networks

Project Area of Specialization

Information & Communication Technology

Project Summary

The handoff process in WiFi networks has a very important role to provide continuity of the service to wireless users where the access points (APs) are in numerous numbers. In traditional WiFi networks, the handoff process takes a few seconds and is initiated by the wireless devices, but these few seconds could be a reason for information loss when dealing with delay sensitive applications. In this project, we propose a reduced detection and discovery time approach (DeRy), which generates a solution based on software defined WiFi networks (SD-WiFi) for next generation wireless networks. A simple network management protocol (SNMP) manager and received signal strength indicator (RSSI) manager are employed to report the AP traffic conditions and RSSI values to the SDN controller and instead of the wireless devices, the handoff decisions are taken at the controller end. When to initiate the handoff (detection phase) and which destination AP to associate to (discovery phase) are handled by the centralized SDN controller. To implement DeRy, extensive simulation runs are carried out on Mininet- NS3-WiFi network simulator. The simulation results are expected show that the DeRy significantly reduces the handoff times by 60–70% and reduces the average number of retransmissions by 4–49%, hence maintaining the throughput for delay sensitive applications such as VoIP, when compared to the standard RSSI-based handoff scheme, channel measurement-based access selection scheme (CMAS) and (DL-SINR) downlink-signal to interference plus noise ratio AP selection scheme (DASA).

Project Objectives

In this project, we propose a DeRy approach that aims to reduce the detection and discovery times during the handoff process by using the advantages of the SDN to improve the overall network performance. The SDN controller having the overall view of the network collects the information of the APs through SNMP and RSSI manager. SNMP manager provides the traffic information of APs and RSSI manager provides the RSSI values of the APs. On collecting AP reports, the SDN controller makes the association/de-association decisions targeting reduced handoff times. The controller decides when to initiate the handoff (detection phase) and re-associates the wireless devices to an appropriate AP (discovery phase). Our solution brings novelty in three ways. The handoffs in the traditional networks only depend on a single metric; that is, RSSI and studies have shown that relying on a single metric for handoff creates crowded hotspots.16 Our solution focuses on reducing the handoff times by considering the traffic load and RSSI values on the APs together. Considering the traffic load minimizes the number of handoffs as the destination AP selected by the controller guarantees the QoS. The second aspect of the proposed study is that both the client side and AP side3 are tamed for reducing the handoff times as compared to the previous studies where only client side or AP side information is considered separately. Finally, our solution does not require any hardware changes and is applicable to any wireless device that supports the OpenFlow standards. The core contributions of this study are as follows:

We propose DeRy to reduce the handoff times in SD-WiFi by using SNMP and RSSI managers. SNMP manager forwards the traffic information to the SDN controller whereas the RSSI manager forwards the APs RSSI information to the controller. On collecting these reports, the controller decides when to trigger handoff (detection phase) and which destination AP to associate to (discovery phase).

We propose a multi-criterion, based on RSSI and traffic load to select an optimal destination AP in order to reduce handoff time and guaranty the QoS.

We create a simulation platform to test the performance evaluation of DeRy for multi number of associations(connections).

Project Implementation Method

The handoff delay is mostly influenced by the discovery and the detection phases. The paper focuses on discovery and detection control in SD-WiFi to improve the handoff time. The centralized SDN controller manages the OpenFlow tables in the APs and having the overall view of the network takes two decisions: (1) when the handoff is needed and (2) which destination AP to associate to. The DeRy architecture is depicted in Figure below. The architecture consists of three planes: application plane, control plane, and the data plane. The data plane depicts applications such as smart homes, healthcare, or campus WiFi where the wireless devices connected to a WiFi network undergo handoffs. The wireless devices forward the RSSI information to the RSSI manager through OpenFlow enabled APs, and on computation, the SDN controller in the control plane chooses a destination AP for the de-associated wireless devices. The RSSI values are extracted from the packets exchanged between the wireless devices and the APs. The traffic information on the APs is collected by the SNMP manager in the application plane. The information helps the SDN controller in deciding a suitable destination AP. The RSSI and the SNMP manager residing in the application plane forward the reports to the SDN controller. On receiving the reports, the SDN controller chooses the most optimal destination AP for wireless devices to re-associate too. values are extracted from the packets exchanged between the wireless devices and the APs. The traffic information on the APs is collected by the SNMP manager in the application plane. The information helps the SDN controller in deciding a suitable destination AP. The RSSI and the SNMP manager residing in the application plane forward the reports to the SDN controller. On receiving the reports, the SDN controller chooses the most optimal destination AP for wireless devices to re-associate too.

Benefits of the Project

In this project, a DeRy approach is proposed to minimize the handoff times and the average number of

retransmissions in SD-WiFi. In traditional WiFi networks, the handoff process is initiated by the wireless devices, thus making it solely vendor dependent. DeRy aims to control the detection phase (when to initiate the handoff) and discovery phase (which AP to re-associate to) through a centralized SDN controller, hence leading towards minimized handoff times. When comparing DeRy to the traditional WiFi networks, the handoff times are reduced by 60–70% which means enhanced communication stability, better throughput and least packet loss. The average number of retransmissions are also reduced in DeRy by 4%, 7%, and 49% when compared to CMAS, DASA, and traditional WiFi networks, respectively. Instead of a single decision metric such as RSSI used in traditional WiFi networks, DeRy approach takes into account both the RSSI and amount of traffic as decision parameters while selecting an optimal destination AP. The results show that the proposed DeRy outperforms traditional WiFi networks in RSSI and handoff time performance with respect to multi number of connections. We plan to extend DeRy by considering other metrics such as throughput and packet loss rate as decision parameters for selection of optimal destination AP in high-density software defined WiFi networks that may result in better QoS for delay sensitive applications.

Technical Details of Final Deliverable

The simulation topology is designed to check the efficiency of DeRy approach regarding the detection phase.. Two simulation runs are carried, one for the traditional WiFi network, where the association decisions are carried by the wireless devices and the second run takes into account the DeRy approach, where RSSI is chosen as the only decision parameter to select the destination AP. Initially, the wireless device is connected to the source AP1. Gradually the wireless device moved towards AP2, de-authenticates from AP1 and connects to AP2. Similarly, the same procedure is repeated from AP2 to AP1. The process of connecting the wireless device from AP1 to AP2 and vice versa was repeated 5 times resulting in 10 connections. The handoff time performance of DeRy is compared to that of the traditional WiFi network. It is observed that the handoff times are efficient and more or less similar when compared to the traditional approach. In some cases, the handoff time of traditional WiFi network is much higher than the DeRy approach by almost 60% which could lead to further delay when dealing with delay sensitive applications such as VoIP.

It is observed during the simulation run that number of times the RSSI value of the AP2 was higher than the source AP but the wireless device did not initiate a handoff. Due to improper decision of whether to or whether not to initiate a handoff, the packets were lost during communication resulting in retransmissions. In contrast, the DeRy approach triggered the detection phase through a centralized controller having an overall view of the network thus maintaining the QoS.

The simulation setup is designed to verify the efficiency of DeRy regarding the discovery phase. In addition to RSSI as only decision parameter in the previous subsection, now the amount of traffic was also considered in the selection of the optimal destination AP. AP3 is enhanced in signal strength of 25 dBm while the other two APs are configured with the same signal strength of 9 dBm. The calibration allowed to have different RSSI values inside a simulation environment. Ten simulation runs are conducted. Initially, the wireless device is connected to the source AP1. Gradually the wireless device moves towards AP2 and AP3. The controller has to choose the best destination AP among AP2 and AP3. It is observed that the handoff times are improved by almost 70% in DeRy as compared to the traditional WiFi network.

Final Deliverable of the Project

Hardware System

Core Industry

Telecommunication

Other Industries

Manufacturing

Core Technology

Internet of Things (IoT)

Other Technologies

Cloud Infrastructure

Sustainable Development Goals

Affordable and Clean Energy, Decent Work and Economic Growth, Industry, Innovation and Infrastructure

Required Resources

If you need this project, please contact me on contact@adikhanofficial.com