Abstract
In any system, whether wireless or wireline, there are signalling procedures that might be repeated each time the subscriber wants to connect to the network. In particular, inside those procedures the contents of one or more messages might be repeated each time the procedure is run. An example of repeated information is signalling or data channel configuration. Such information might be large in size, in which case any storage method that avoids sending this repeated information would reduce procedure processing and setup delays. The gain becomes more relevant when the signalling procedure is run over the air interface. In this thesis a novel generic storage method is proposed which results in a significant reduction in signalling messages exchanged between a user’s equipment and network over the air interface. Besides acting as a limit to achievable spectral efficiency the signalling overhead is a limit to energy efficiency and can cause delay in a session setup. The problem will become more important as the trend moves towards smaller and smaller cells in support of huge mobile data traffic in 2020 in future mobile broadband internet due to mobility-related signalling. As an example, in a call setup procedure the saving is achieved by splitting messages into two steps. The first step is during the first call where only a part of one or many messages in the procedure is stored. The second step is during the second call, where the remaining parts of the messages that were stored in the first step are transmitted. Such a method not only stores part of a signalling message but also, depending on the procedure used, the contents of a whole message. As a result, not only is the number of signalling messages that are exchanged reduced but also the receiver can start applying the contents of an already stored message in advance over the standard procedure. This is because the receiver does not have to wait anymore for a message to read its contents and take action, rather it reads the stored contents. To demonstrate the effectiveness of this novel method, 3rd generation mobile standard, a UMTS (Universal Mobile Telecommunication System) call setup procedure is used and the new method is applied to it with a restriction that the new call setup procedure is still standard compliant. Results of the application of the new method to different UMTS procedures show significant gains in terms of size, duration and processing. As the UMTS call setup is the main signalling procedure studied in this thesis, a novel method of, not using a storage algorithm, is proposed. It works as follows: with the standard methods part of the UMTS call setup is sent at 3. 4 kbps and another part is sent at 13. 6 kbps, whereas with the proposed method all messages are sent at 13. 6 kbps. This is done by postponing the activation of the radio channel configuration. The method is then applied to the UMTS emergency call where an A-GPS (Assisted Global Positioning System) is used to locate the UE (User Equipment). As a result the signalling delay is largely reduced.