Investigation into the Limitations of MPEG-2 Codecs and IP-Based Networks for Large-Scale ITS Deployments, 10-9401Printer Friendly Version
Inclusive Dates: 06/23/03 - 10/23/03
Background - SwRI has been involved in communications infrastructure design for Intelligent Transportation Systems (ITS) for several years. Previous work dealt with Motion Picture Experts Group (MPEG-2) compressed video over Asynchronous Transfer Mode (ATM) networks, as these were the technologies that SwRI recommended for our clients to pursue at that time. Recent developments have led smaller Departments of Transportation (DOT) to investigate the possibility of implementing emerging technologies associated with Internet Protocol (IP) based networks as opposed to ATM. We believe that there will soon be a strong push in the ITS community to deploy these technologies in communications infrastructures. SwRI had some experience working with IP technology but needed to come up the learning curve on several key issues that will directly impact future ITS deployments.
This program was undertaken to investigate the emerging technologies associated with MPEG-2 over IP, Gigabit Ethernet backbone networking, IP Multicasting, Internet Group Management Protocol (IGMP) Snooping, Spanning Tree, and Rapid Spanning Tree Protocols, and to look into the recent developments with Class of Service (CoS) and Quality of Service (QoS) for IP that would impact the feasibility of deploying these technologies in a large scale ITS infrastructure.
Approach - The original proposal defined a research-based approach of identifying applicable industry standards, analyzing these standards for ambiguity, and correlating these standards to SwRI's knowledge of and experience with large-scale ITS networks. From this research, a working network architecture was designed and applicable product was researched to provide a springboard for SwRI to foster discussions with potential customers. The figure below depicts the preliminary working diagram. The principal areas investigated were:
Results from this program were presented in the final report in a way to serve as a tutorial for other SwRI staff not directly involved with this effort to use as a reference when discussing the potential performance and interoperability issues with equipment vendors and customers. All referenced standards and subsequent technical articles were archived to enable externally funded projects to build upon this research.
Accomplishments - As of the recent completion of this program, technical benefits are already being felt. Ongoing work with existing customers has benefited from technical details brought forth in this report, and discussions with other potential customers have begun. It is expected that as a result of this program, SwRI will be better prepared to assist our ITS customers with their technical challenges in the years to follow.