Mobile connectivity protocols and throughput measurements in the Ricochet Microcellular data network (MCDN) system

ABSTRACT

We describe the protocols implemented in the Ricochet MCDN system to provide continuous connectivity to mobile users traveling up to 70 mph. These protocols are general in nature for any frequency-hopping microcell-based system, particularly those that follow the FCC part 15.247 rules [9] and operate in unlicensed spectrum. We also present throughput measurements as a function of velocity and describe a model to predict those numbers based upon the protocols implemented. The MCDN system is a mesh-based system of microcells that are connected wirelessly to an interspersed mesh of wired access points (WAPs) that cover approximately 12 square miles on average [7]. The average microcell density is approximately 5-6 per square mile, with 3-8 overlapping cells at each point. Since the system is entirely packet-based, we have instantaneous hand-off between microcells as there are no complicated cellular-type negotiations for circuits required as all of the information needed to route the packet through the system is included in the header; however, when traveling through the mesh of microcells at a high rate of speed, the mobile unit must acquire new microcells fast enough to ensure continuous connectivity. The system must also know how to route packets to the mobile unit as it drops old cells and acquires new ones, as well as being able to contact a moving mobile unit. This paper discusses the acquisition, registration, and routing protocols that make this possible and reviews performance data of typical mobile users.

REFERENCES

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INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.1 PROCESSOR ARCHITECTURES
      C.1.3 Other Architecture Styles
          Subjects: Cellular architecture (e.g., mobile)

Additional Classification:
  C. Computer Systems Organization
  C.2 COMPUTER-COMMUNICATION NETWORKS
      C.2.1 Network Architecture and Design
          Subjects: Network communications
  C.4 PERFORMANCE OF SYSTEMS
      Subjects: Performance attributes

General Terms:
Design, Measurement, Performance

Keywords:
MCDN system architecture, Mobility, wireless networks, wireless protocols, wireless routing