A Brief Survey of Media Access Control, Data Link Layer, and Protocol Technologies for Lunar Surface Communications

This paper surveys and describes some of the existing media access control and data link layer technologies for possible application in lunar surface communications and the advanced wideband Direct Sequence Code Division Multiple Access (DSCDMA) conceptual systems utilizing phased-array technology that will evolve in the next decade. Time Domain Multiple Access (TDMA) and Code Division Multiple Access (CDMA) are standard Media Access Control (MAC) techniques that can be incorporated into lunar surface communications architectures. Another novel hybrid technique that is recently being developed for use with smart antenna technology combines the advantages of CDMA with those of TDMA. The relatively new and sundry wireless LAN data link layer protocols that are continually under development offer distinct advantages for lunar surface applications over the legacy protocols which are not wireless. Also several communication transport and routing protocols can be chosen with characteristics commensurate with smart antenna systems to provide spacecraft communications for links exhibiting high capacity on the surface of the Moon. The proper choices depend on the specific communication requirements

TCP over Satellite Hybrid Networks: A Survey

Satellite is going to play an important role in the global information infrastructure. Satellite canprovide direct to home Internet service (i.e. DirecPC from Hughes Network System) and it can alsoserve as traffic trunk in the middle of the network. About 98 percent of the Internet traffic is TCPtraffic. TCP works well in the terrestrial fiber network. However, in the satellite hybrid networks,because of the long propagation delay, large bandwidth-delay product, high bit error rate anddownstream/upstream bandwidth asymmetry, TCP performance degrades dramatically. This paperaddresses the problems of TCP in satellite data networks and reviews the proposed solutions in theliterature. For each solution, the advantages and disadvantages are pointed out. In addition,extensive simulations have been done for the proxy based scheme currently used in the industry tofind out how and to what extent the enhancements, such as connection splitting, window scalingand selective acknowledgement, benefit the TCP throughput

A Comparative Analysis of Transmission Control Protocol Improvement Techniques over Space-Based Transmission Media

The purpose of this study was to assess the throughput improvement afforded by the various TCP optimization techniques, with respect to a simulated geosynchronous satellite system, to provide a cost justification for the implementation of a given enhancement technique. The research questions were answered through model and simulation of a satellite transmission system via a Linux-based network topology; results of the simulation were analyzed primarily via a non-parametric method to ascertain performance differences between the various TCP optimization techniques. It was determined that each technique studied, which included the Space Communication Protocol Standard-Transport Protocol (SCPS-TP), window scale, selective acknowledgements (SACKs), and combinational use of the window scale and SACK mechanisms, provided varying levels of improvement as compared to a standard TCP implementation. In terms of throughput, SCPS-TP provided the greatest overall improvement, with window scale and window scale/SACK techniques providing significant benefits at low levels of bit error rate (BER). The SACK modification improved throughput performance at high levels of BER, but performed at levels comparable to standard TCP during scenarios with lower BER levels. These findings will be of assistance to communications planners in deciding whether or not to implement a given enhancement or deciding which technique to utilize

MAXIMIZING DATA DOWNLOAD CAPABILITIES FOR FUTURE CONSTELLATION SPACE MISSIONS

We outline the first step toward the development of a unified space communication network approach, offering more flexibility, robustness, expandability and compatibility with terrestrial networks. The aim is to maximize the data download capabilities of future missions while reducing the development and operational costs. We introduce the current State-of-the-Art in space communications, present the benefits of a unified approach and discuss some challenges that need to be addressed to enable this transition. We focus on developing a suitable dynamic routing algorithm and a reconfigurable simulation framework. A case study on the Magnetospheric Multi-Scale constellation mission shows that both NASAs Deep Space Network and some commercial ground facilities can provide sufficient coverage for this mission and demonstrates the benefits of a unified space network. We also demonstrate the usefulness of a modular simulation framework as a low-cost but powerful tool for evaluating the performance of protocols and architectures in this environment

Congestion management in access networks with long propagation delay

Satellite networks are going to play an important role in the global information infrastructure. Satellites can be used to provide Internet services to fixed users and to mobile users. However, recent measurements show that the satellite link efficiency is only about 30%. In order to improve the performance of Internet over satellite, a new protocol called Receiver Window Backpressure Protocol (RWBP) is proposed. RWBP uses per-flow queuing, round robin scheduling and receiver window backpressure for congestion management. Simulation results show that RWBP can maintain high utilization of the satellite link and improve fairness among the competing connections

An investigation into intelligent network congestion control strategies

This thesis examines the congestion control issues that arise in Intelligent Networks, when it is necessary to support multiple service types with different load requirements and priorities. The area of Intelligent Network (IN) congestion control has been under investigation for over a decade, but in general, the models used in this research were over-simplified and all service types were assumed to have the same priority levels and load requirements at the various IN physical elements. However, as the IN is a dynamic network that must process many different service types that have radically different call load profiles and are based on different service level agreements and charging schemes, the validity of the above assumptions is questionable. The aim of this work, therefore, is to remove a number of the classic assumptions made in IN congestion control research, by: • developing a detailed model of an IN, catering for multiple traffic types, • using this model to establish the shortcomings of classic congestion control strategies, • devising a new IN congestion control strategy and verifying its superiority on the model. To achieve these aims, an IN model (both simulation and analytic) is developed to reflect the physical and functional architecture of the network and model the information flows required between network entities in order to execute services. The effectiveness of various classic active and reactive congestion control strategies are then investigated using this model and it is established that none of these strategies are capable of protecting both the Service Control Point and Service Switching Points under all possible traffic mixes and loads. This is partially due to the fact that all of these strategies are based on the use of fixed parameters (and are therefore not flexible enough to deal with IN traffic) and partially because none of these strategies take into account the different load requirements of the different service types. A new, flexible strategy is then devised to facilitate global IN congestion control and cater for service types with different characteristics. This strategy maximises IN performance by protecting all network elements from overload while maximising network revenue and preserving fairness between service types during overload. A number of factors determining the relative importance or weight of different traffic types are also identified and used by the strategy to maintain call importance during overload. The efficiency of this strategy is demonstrated by comparing its operation to that of the best classic IN overload controls and also to a new strategy, which has scalable and dynamic behaviour (and which was devised for the purpose of providing a fair comparison to the optimisation strategy). The optimisation-based strategy and dynamic strategy are found to be equally effective and far superior to the classic strategies. However, the optimisation algorithm also preserves relative importance and fairness, while maximising network revenue - but at the cost of a not insignificant processing overhead

Network Simulation Cradle

This thesis proposes the use of real world network stacks instead of protocol abstractions in a network simulator, bringing the actual code used in computer systems inside the simulator and allowing for greater simulation accuracy. Specifically, a framework called the Network Simulation Cradle is created that supports the kernel source code from FreeBSD, OpenBSD and Linux to make the network stacks from these systems available to the popular network simulator ns-2. Simulating with these real world network stacks reveals situations where the result differs significantly from ns-2's TCP models. The simulated network stacks are able to be directly compared to the same operating system running on an actual machine, making validation simple. When measuring the packet traces produced on a test network and in simulation the results are nearly identical, a level of accuracy previously unavailable using traditional TCP simulation models. The results of simulations run comparing ns-2 TCP models and our framework are presented in this dissertation along with validation studies of our framework showing how closely simulation resembles real world computers. Using real world stacks to simulate TCP is a complementary approach to using the existing TCP models and provides an extra level of validation. This way of simulating TCP and other protocols provides the network researcher or engineer new possibilities. One example is using the framework as a protocol development environment, which allows user-level development of protocols with a standard set of reproducible tests, the ability to test scenarios which are costly or impossible to build physically, and being able to trace and debug the protocol code without affecting results

SATELLITE BASED DATA COMMUNICATION: A SURVEY

ABSTRACT Satellite communication is well known in providing best services where broadcasting is essential, where terrain is hostile and very sparsely populated. It also has niche where rapid deployment is very critical and important. In Global Network Infrastructure satellite is considered as an inseparable component of the communication infrastructure. A variety of research work has been explored and published for satellite based data communication & networking. It is utmost important to conduct a survey on different aspects and research issues of satellite based communication with a focus on the latest development. In this paper, we summarize, compare & comments on the approaches proposed for the satellite based data communication with keeping in view the parameters like Quality of service, Interplanetary Internet, Mobility management, explicit load balancing and packet reordering issue

Performance Analysis of Transactional Traffic in Mobile Ad-hoc Networks

Mobile Ad Hoc networks (MANETs) present unique challenge to new protocol design, especially in scenarios where nodes are highly mobile. Routing protocols performance is essential to the performance of wireless networks especially in mobile ad-hoc scenarios. The development of new routing protocols requires com- paring them against well-known protocols in various simulation environments. The protocols should be analysed under realistic conditions including, but not limited to, representative data transmission models, limited buffer space for data transmission, sensible simulation area and transmission range combination, and realistic moving patterns of the mobiles nodes. Furthermore, application traffic like transactional application traffic has not been investigated for domain-specific MANETs scenarios. Overall, there are not enough performance comparison work in the past literatures. This thesis presents extensive performance comparison among MANETs comparing transactional traffic including both highly-dynamic environment as well as low-mobility cases

TRANSPORT PROTOCOL AND FLOW CONTROL FOR IP-BASED BROADBAND AERONAUTICAL SATELLITE NETWORKS

The IP-based broadband aeronautical satellite network will provide numerous new applications and services for both airspace system operations and passenger communications. However, the interoperation between a satellite system and the exiting terrestrial Internet infrastructure introduces new challenges. In this thesis, we recommend suitable transport protocols for an aeronautical network supporting Internet and data services via satellite. We study the future IP-based aeronautical satellite hybrid network and focus on the problems that cause dramatically degraded performance of the Transport Protocol. Based on the observation that it is difficult for an end-to-end TCP solution to solve the performance problem effectively, we proposed a new splitting based transport protocol, called Aeronautical Transport Control Protocol (AeroTCP). The main idea of AeroTCP is the fixed window flow control, adaptive congestion control, and super fast error control. Simulation results showed that AeroTCP can achieve high utilization of satellite channel and fairness