Hier werden die Unterschiede zwischen zwei Versionen angezeigt.
| Beide Seiten der vorigen Revision Vorhergehende Überarbeitung Nächste Überarbeitung | Vorhergehende Überarbeitung | ||
|
forschung:applying_formal_methods_for_qos_provisioning_in_mobile_architectures [2009/09/24 16:48] barakat |
forschung:applying_formal_methods_for_qos_provisioning_in_mobile_architectures [2011/10/28 14:37] barakat |
||
|---|---|---|---|
| Zeile 3: | Zeile 3: | ||
| \\ | \\ | ||
| \\ | \\ | ||
| + | <style justify> | ||
| This project focuses on the application of formal methods to model and manage QoS for Network Mobility. {{ :forschung:image007.jpg|}}The field of network mobility is gaining ground in telecommunications because of the evolution of broadband technologies and the increasing applications that demand broadband access, e.g. connectivity in public transportation and IMS. Network Mobility is the field that considers sets of mobile devices moving together as one entity with one or more access points which are called mobile routers. These networks are standardized under the IETF-RFC3963 specification also known as NEMO Basic Support, while QoS challenges are described in IETF-RFC4980. NEMO BS is an extension to MIPv6 described under IETF-RFC3775. Mobile routers can possess multiple Radio Access Technologies (RATs) and have to perform real-time operations, e.g. handover, managing binding updates, merging/splitting mobile networks and managing QoS. The intelligent management of mobility, data streams of different QoS requirements and the available RATs makes the formalization of this problem a necessity due to its complexity. The importance of this study comes from the industry focus on network operator’s IP services, especially IMS. NEMO BS provides a solution for this system and at the same time requires investment in research to improve QoS. | This project focuses on the application of formal methods to model and manage QoS for Network Mobility. {{ :forschung:image007.jpg|}}The field of network mobility is gaining ground in telecommunications because of the evolution of broadband technologies and the increasing applications that demand broadband access, e.g. connectivity in public transportation and IMS. Network Mobility is the field that considers sets of mobile devices moving together as one entity with one or more access points which are called mobile routers. These networks are standardized under the IETF-RFC3963 specification also known as NEMO Basic Support, while QoS challenges are described in IETF-RFC4980. NEMO BS is an extension to MIPv6 described under IETF-RFC3775. Mobile routers can possess multiple Radio Access Technologies (RATs) and have to perform real-time operations, e.g. handover, managing binding updates, merging/splitting mobile networks and managing QoS. The intelligent management of mobility, data streams of different QoS requirements and the available RATs makes the formalization of this problem a necessity due to its complexity. The importance of this study comes from the industry focus on network operator’s IP services, especially IMS. NEMO BS provides a solution for this system and at the same time requires investment in research to improve QoS. | ||
| + | </style> | ||
| \\ | \\ | ||
| === Work Plan === | === Work Plan === | ||
| + | <style justify> | ||
| This work consists of two main parts; building the formal model and simulating the NEMO protocol. These parts are to be run in parallel to achieve interdependability between each other. This means that simulation measurements will be used to support theoretic hypothesis made by the formalized description of the QoS problem. On the other hand, formal tools have to be implemented in order to be able to incorporate extensions which in turn will allow making predictions of the behavior of the modeled system in a similar way to simulations. This means that these tools will be designed to be able to generate quantitative as well as qualitative conclusions. | This work consists of two main parts; building the formal model and simulating the NEMO protocol. These parts are to be run in parallel to achieve interdependability between each other. This means that simulation measurements will be used to support theoretic hypothesis made by the formalized description of the QoS problem. On the other hand, formal tools have to be implemented in order to be able to incorporate extensions which in turn will allow making predictions of the behavior of the modeled system in a similar way to simulations. This means that these tools will be designed to be able to generate quantitative as well as qualitative conclusions. | ||
| + | </style> | ||
| \\ | \\ | ||
| Zeile 473: | Zeile 477: | ||
| </html> | </html> | ||
| + | <style justify> | ||
| Π-Calculus is a modeling formality that focuses on communicating processes. It offers firm representation of connectivity and messaging using math-like expressions. Π-Calculus had initially a monadic syntax where single arguments are passed through channels. Later on, polyadic π-Calculus was introduced to allow pushing sets of arguments at once over the communication channels. Process replication was also introduced. In the higher order π-Calculus, process names can be exchanged through the channels too. Some research uses available syntax to express problems like QoS while others ground their own flavor of it by introducing modifications to the syntax like spi-Calculus which is specifically suitable for cryptology. One more example is Ambient-Calculus which concerns itself with defining computation domains or ambiences where communication between local processes happens within its boundary, ambiences can move and communication crossing the border is analogous to crossing firewalls. The extensibility, expressiveness, flexibility and firm formality of π-Calculus make it the most suitable tool for modeling communication protocols and prototypes of enhancements. This work aims to make further contributions to π-Calculus in order to achieve the following: | Π-Calculus is a modeling formality that focuses on communicating processes. It offers firm representation of connectivity and messaging using math-like expressions. Π-Calculus had initially a monadic syntax where single arguments are passed through channels. Later on, polyadic π-Calculus was introduced to allow pushing sets of arguments at once over the communication channels. Process replication was also introduced. In the higher order π-Calculus, process names can be exchanged through the channels too. Some research uses available syntax to express problems like QoS while others ground their own flavor of it by introducing modifications to the syntax like spi-Calculus which is specifically suitable for cryptology. One more example is Ambient-Calculus which concerns itself with defining computation domains or ambiences where communication between local processes happens within its boundary, ambiences can move and communication crossing the border is analogous to crossing firewalls. The extensibility, expressiveness, flexibility and firm formality of π-Calculus make it the most suitable tool for modeling communication protocols and prototypes of enhancements. This work aims to make further contributions to π-Calculus in order to achieve the following: | ||
| * Π-Calculus is founded on the principle of state automata. Consequently, processes in π-Calculus interact and switch their states upon reception of messages over communication channels, which means that message reception among processes triggers the interaction and causes the system to evolve. However, modeling real-world systems needs more than that. The notion of time is currently unavailable in the syntax of π-Calculus, which makes it unsuitable for performing simulations in which particular events take place at certain points of time, e.g. time-out events. In this work we aim to introduce a new component in the syntax of π-Calculus to enable it to model timed events. | * Π-Calculus is founded on the principle of state automata. Consequently, processes in π-Calculus interact and switch their states upon reception of messages over communication channels, which means that message reception among processes triggers the interaction and causes the system to evolve. However, modeling real-world systems needs more than that. The notion of time is currently unavailable in the syntax of π-Calculus, which makes it unsuitable for performing simulations in which particular events take place at certain points of time, e.g. time-out events. In this work we aim to introduce a new component in the syntax of π-Calculus to enable it to model timed events. | ||
| Zeile 480: | Zeile 484: | ||
| * A π-Calculus model for NEMO BS has to be built as described in RFC3963. Software development of the protocol under the simulation tool and QoS enhancements should be based on this model. This is important to ensure strong analogy interrelationships between simulation measurements and the qualitative deductions made from the formal model. | * A π-Calculus model for NEMO BS has to be built as described in RFC3963. Software development of the protocol under the simulation tool and QoS enhancements should be based on this model. This is important to ensure strong analogy interrelationships between simulation measurements and the qualitative deductions made from the formal model. | ||
| * Depending on the interdependency between simulation and formal model verification results further studies can evolve to explain observed phenomena and try to set rules to make this relation deterministic. | * Depending on the interdependency between simulation and formal model verification results further studies can evolve to explain observed phenomena and try to set rules to make this relation deterministic. | ||
| + | |||
| \\ | \\ | ||
| Zeile 486: | Zeile 491: | ||
| * It allows quantitatively comparing formal models and making early choices about modifications and improvements. | * It allows quantitatively comparing formal models and making early choices about modifications and improvements. | ||
| * It shortens the software development cycle by limiting the need to go back to the model and make modifications for issues discovered after implementation. | * It shortens the software development cycle by limiting the need to go back to the model and make modifications for issues discovered after implementation. | ||
| + | |||
| + | Our simulator tool SimPiCal can be found [[http://web.embedded.rwth-aachen.de/pical/|here]]. | ||
| + | </style> | ||
| \\ | \\ | ||
| === Simulating the Protocol === | === Simulating the Protocol === | ||
| \\ | \\ | ||
| - | {{ :forschung:image009.jpg |Copyright OPNET Technologies, Inc.(r)}} | ||
| \\ | \\ | ||
| - | For this purpose OPNET Modeler® is being used under university licensing. This simulator contains a huge library of standardized protocols and devices as well as commercial ones, e.g. MIPv6 and mobile routers. The hierarchical structure of components and their modular design shortens the time required to develop own devices and extend particular protocols. To complete the required infrastructure for performing simulations the following tasks are ahead: | + | {{ :en:forschung:opnet.jpg |}} |
| + | \\ | ||
| + | \\ | ||
| + | <style justify> | ||
| + | For this purpose OPNET Modeler® is being used under university licensing. This simulator contains a huge library of standardized protocols and devices as well as commercial ones, e.g. MIPv6 and mobile routers. The hierarchical structure of components and their modular design shortens the time required to develop own devices and extend particular protocols. [[http://web.embedded.rwth-aachen.de/opnet/|<more info>]] | ||
| + | </style> | ||
| - | {{ :forschung:image011.jpg |Copyright OPNET Technologies, Inc.(r)}} | + | \\ |
| + | === Acknowledgement === | ||
| + | This work was funded by the DFG Cluster of Excellence on Ultra-high Speed Information and Communication (UMIC), German Research Foundation grant DFG EXC 89. | ||
| - | * Create a multi-RAT router on which the NEMO BS protocol is going to be run. Multiple RAT interfaces are necessary to study the effect of access technology switching on ongoing data sessions and to test possible QoS enhancements and strategies. This router shares its network layer between the different RATs by setting MIPv6 on top of Link Layer (LL) and Radio Resource Control (RRC) layers of available RATs. Each RAT will have its own physical, MAC, LL, Radio Link Control (RLC) and RRC of its own. On top of MIPv6 NEMO BS is going to be implemented. This structure allows for unified session management and QoS control. For this research, WiFi, WiMAX and LTE are going to be the RATs of our mobile routers. | ||
| - | * Create core-network components that will provide the required messaging to perform handover and domain administration. These components are described in 3GPP-23.401 and 3GPP-23.402. These specifications describe network structure for different scenarios (homing or visiting) in addition to mobility management, network selection, network access strategies and QoS provisioning. | ||
| - | * NEMO BS has to be modeled using our extensions of π-Calculus. Afterwards, the protocol can be implemented for simulation based on the prototyped model. This has to be done in this order because strong interdependency between simulation and formalization is required for further study purposes. | ||
| - | * Extend MIPv6 to include NEMO BS as described in RFC3963 and according to the prototyped π-Calculus model. To allow code-reuse NEMO BS will be written above an abstraction layer that will integrate it with OPNET. | ||
| - | * Integrate the NEMO BS extension with OPNET. At this point, full functionality of NEMO BS should be available for testing. | ||
| - | * Create test scenarios for use with simulations. These scenarios will be based on the use cases described in 3GPP-22.259. This document describes use-cases for PANs in IMS for which NEMO BS represents a suitable solution. This particular approach has been chosen in order to keep a close to industry requirements. | ||
| - | * Collect baseline measurements against which QoS improvements are going to be evaluated. | ||
| - | * Modify the implementation of NEMO BS to propagate the QoS improvements made using the π-Calculus based model and collect simulation measurements. These measurements will be compared with the baseline results to assess the improvements. In addition, they will be semantically compared to the quantitative attributes of the QoS improved model to see how these results match or differ. | ||
| \\ | \\ | ||
| === References === | === References === | ||
| + | <style justify> | ||
| - 3GPP-23.401 General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access. | - 3GPP-23.401 General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access. | ||
| - 3GPP-23.402 Architecture enhancements for non-3GPP accesses. | - 3GPP-23.402 Architecture enhancements for non-3GPP accesses. | ||
| Zeile 518: | Zeile 524: | ||
| - R. Milner. The Polyadic π-calculus: a tutorial. ECS-LFCS-89-85 91-180, University of Edinburgh, 1991. | - R. Milner. The Polyadic π-calculus: a tutorial. ECS-LFCS-89-85 91-180, University of Edinburgh, 1991. | ||
| - Claus Pahl, A PiCalculus based Framework for the Composition and Replacement of Components. In Workshop on Specification and Verification of Component-Based Systems (OOPSLA 2001), 2001. | - Claus Pahl, A PiCalculus based Framework for the Composition and Replacement of Components. In Workshop on Specification and Verification of Component-Based Systems (OOPSLA 2001), 2001. | ||
| + | </style> | ||
| \\ | \\ | ||