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27.3.2017 : 12:32

Technical Highlights: System architecture and interfaces

The two first tasks of WP2 are now completed and their outcomes are summarized hereafter.

T2.1 was in charged of positioning and splitting the decisions in the global architecture and then identifying the different network architecture options to consider. 

T2.2 main objectives consisted in implementing the QoSMOS scenarios into these options, progressing the system specification, and defining the performance metrics for system evaluation.

Reference Model

WP2 gathers input from WP3, WP4, WP5 and WP6 to build a common reference model which defines the functional blocks needed to address the QoSMOS scenarios. The interactions between those blocks captured in the reference model crystallize the positioning and splitting of the decision making in the architecture. 

QoSMOS reference model


  • The "Spectrum Sensing" entity is responsible for controlling the sensing process by interacting with the sensor, for making decision based in sensing measurements, and to report the sensing measurements back to the requesting cognitive management entities.
  • The "Cognitive Manager for Spectrum Management" (CM-SM) is responsible for building the spectrum portfolio based on the external constraints and on spectrum sensing results. This spectrum portfolio contains spectrum usage policies and spectrum usage information, putting constraints on the decisions which can be taken by the other cognitive entities of the QoSMOS system.
  • The "Cognitive Manager for Resource Management" (CM-RM) is responsible for providing service to the application layer according to an agreed level of quality of service (QoS). This includes being responsible for the allocation of the spectrum following the policies contained in the spectrum portfolio, managing the mobility of the users and protecting the incumbent users
  • The "Transceiver" entity is able to perform synchronized data transmission and to provide unidirectional or bidirectional dedicated broadcast and multicast channels on different spectrum band operated by the supported heterogeneous radio access technologies. Additionally, it provides CM-RM with measurement reports and transceiver capabilities (i.e. capabilities to transmit and receive data).
  • The "Common Portfolio Repository" entity is used to store the spectrum portfolio and to exchange context information among network entities. The information includes available frequency bands and spectrum usage policies….
  • The "Global & Local Regulations Policy Databases" entity is used to provide regulatory information for spectrum assignment (licensee status, usage requirements).
  • The "Adaptation Layer" entity provides a seamless and RAT-agnostic communication between some of the different functional entities. This mainly applies to the communication in heterogeneous configurations to facilitate the data exchange between different network elements.
  • The "User Application" entity represents any application running on a user terminal providing a service to an end-user, and requiring access to the network. The user application should be able to express its requirements in terms of QoS for the CM-RMs to decide on admitting or refusing the associated service.
  • The "Network Coordination" entity has the overall responsibility of the configuration of an operator’s infrastructure network. It includes part of the mobility management, and monitors the overall performance of the networks under its control to eventually decide on the reconfiguration of network segments.


The different topologies relative to resource control (centralized, distributed, semi-distributed) and spectral sensing (centralized with overlapped or non-overlapped sets, or distributed) have been combined to form the different architecture options to be considered by the QoSMOS system. These possibilities are depicted in the following figure.

Relations between the topologies’ combinations and the QoSMOS scenarios


Architecture options

The architecture options are based on the topologies combinations and define how functional entities are deployed within the system elements involved in each topology.

As an example following figure depicts the case where both resource control and spectrum sensing functionalities are distributed across the peer network elements. For more information, please refer to [undefinedD2.3].

Architecture view for “distributed resource control with distributed spectrum sensing (RCD-SSD)” topology


Message Sequence Charts

Based on the use cases defined in [undefinedD1.1] and [undefinedD1.2], elementary procedures have been identified to show the interactions between the QoSMOS functional blocks These procedures will be later use for the definition of the protocols associated to the interfaces. Message Sequence Charts associated to these elementary procedures are provided in [undefinedD2.2] and [undefinedD2.3].

Dependencies between QoSMOS MSCs


Performance metrics

Evaluation criteria and performance metrics have been defined for comparing the different solutions considered in the project, which are built on the mapping of functional architectures to topologies and scenarios together with the implementation of the corresponding algorithms.

The criteria and metrics are designed in such a way that the overall performance of the system is fairly and consistently assessed on a technical basis. It should be noted that it is the overall performance of the system that is addressed by WP2 and hence the corresponding criteria and metrics for the components of the QoSMOS system must be derived from the overall criteria and metrics.

Metrics associated to service performance Metrics associated to spectrum utilization
User throughput Spectrum efficiency
End-to-end delay Overhead
Grade of Service (GoS) Frequency re-selection time
User fairness Sensing performance – false incumbent detection
Dropped session probability Sensing performance – missed incumbent detection
Handover failure Air interface flexibility
  Spectrum information timeliness
  Operator fairness



Many standards address architecture issues and/or PHY/MAC designs related to the operation in White Spaces. These standards have been studied to identify communalities with the QoSMOS scope and to prepare the dissemination of QoSMOS results related to the architecture. The standards which may influence (or be influenced by) QoSMOS architecture are:

  • ETSI RRS (Functional Architecture and Cognitive Pilot Channel)
  • IEEE 1900.4-2009, P1900.4a, P1900.4.1
  • IEEE P1900.6
  • IEEE 802.21
  • IEEE 802.19
  • IEEE 802.11af
  • IEEE 802.22

Analysis of these standards with respect to QoSMOS scope can be found in [undefinedD2.1]. More details on these standards are available here.