DECT Based Project Examples

This work involved development of the DECT protocol stack itself at all layers including MAC, DLC, NWK, IWU and application and then integration onto numerous platforms for different end clients, TBR22 conformance testing and novel application development.

DECT Protocol Stack Development

For this project we worked in conjunction with the clients own development team to produce a complete DECT stack. The project involved interpretation of the relevant parts of the DECT ETSI specifications, high level design of that functionality using SDL, implementation in 'C' initially on a PC platform and then finally porting to a reference hardware platform.

Test of individual functionality modules was achieved using a custom test harness to inject messages at appropriate points in the stack and detect the outcome. This test harness was also used to test and debug at the module, layer or complete stack level.
As the ETSI specifications were modified/updated by the ETSI committee, changes were implemented initially within the SDL high level design environment and then at the coding level. We would also implement new features and services (such as data transfer) as they were introduced by ETSI.

DECT Integration and Porting Projects

This development involved porting a DECT stack to various hardware platforms using different microprocessor cores, burst mode controllers and radio modules. The majority of the protocol stack modifications were required at the MAC level to enable interface with different radio and burst mode controller (BMC) modules. Each implementation also involved writing different MMI and Inter Working Unit modules. For a residential handset this covered the keyboard, LCD display contents and menu system, for a base-station this covered interfacing to fixed telephone lines and operation of hook-switch, battery charging and external buttons. For a business system base-station, this involved interfacing with PABX code.

DECT GAP Conformance Testing

This project involved setting up and running TBR22 test scripts to check for GAP (Generic Access Profile) compliance of the DECT stack. Where non-compliance was found, two possibilities existed: The first and usual case was that the stack did not conform; appropriate remedial action was then taken. However, occasionally there were mistakes in the test scripts themselves. Identification, submission and confirmation of the problem then led to ETSI correcting the scripts.

DECT Messaging System

For this project our client proposed to update their existing specialist analogue paging systems with digital technology to produce a more resilient and feature rich system. DECT was chosen as it is a mature and well proven technology. However, the client did not possess the in-house expertise for evaluation or development of the system.

We were approached initially to provide consultancy on DECT system design, software design and operational issues as they applied to the proposed system. A major issue was cost, as their target market is cost sensitive. We proposed a novel system design that met the requirements for up to 2000 subscribers with guaranteed message distribution times. After agreeing a base system topology, we were contracted to produce a documentation suite including a System Requirements Specification, Functional Specification, Detailed Design, Interface Specifications and Test Specifications. These were all successfully delivered on time and to a fixed budget.

The project continued with us writing new application layers for the chosen third party DECT stack. The nature of the system required significant modification of the stack and the need to understand the stack software implementation, for which we were given the source code. Stack documentation was minimal as the stack vendor had not been through this exercise previously, with previous changes being performed in-house. This represented a significant challenge in interpersonal communication with the stack vendor's engineers; whose English I am happy to say was far better than our Danish!

Following the success of the project Raycomm were subsequently contracted to develop other parts of the system, including a central controller unit. This unit controlled up to 32 DECT Fixed Parts, interfaced remotely via a modem to a serially connected configuration terminal, interfaced to an Ethernet connected management terminal and connected to our client's own existing infrastructure.

The central controller unit included an embedded TCP/IP stack. Communication between the central controller and the FPs was by UDP/IP/Ethernet with a bespoke transport protocol. The unit also handled text message distribution and delivery verification, registration database management, distribution and authentication functions.

Due to the success of our partnership we also developed several Portable Part User Interfaces to sit on a common application layer for different applications which were originally planned to be written in-house.

DECT Based Wireless Management System

This project was for various applications centred around team management for fast food outlets and supermarket chains.

The project brief was to design the hardware and software for the central control unit, and also to design special builds for targeted applications that were not practical to include in the main design. The product had a very wide range of target uses which proved this to be a challenging but enjoyable project.

The design utilised a 16F84 PIC micro and a CENS90200 audio processing DSP for echo and noise cancellation. I2S digital audio technology was also used ( TLC320AD77 CODEC's ). The product had two parts a main control board and a small remote card which took in microphone audio and converted to digital I2S to transport to the main board. Other inputs to the main board included a loop vehicle sensor, an ultrasonic sensor, RS232 and RS422 data inputs. The system utilised customised Inventel DECT modules.

Raycomm are a UK based, custom software and electronics design and development service company creating bespoke electronic products, mobile device software applications, backend web server software and e-commerce database software.