APPENDIX
Serial Bus Protocol
2.10
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19.01.2007
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5.3.3 CLDPS
CLDPS is a packet based protocol for connection-less data transfer through the DECT air
interface.
The advantages of the connection-less data transfer are:
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the available system data capacity is dynamically distributed to the PTs according to the
demand.
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thus a large amount of PTs - with the corresponding low bandwidth - may be operated
simultaneously.
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a PT may occupy a high capacity for a short period of time in order to transfer a data
burst.
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PTs will only occupy a channel if payload data are to be transferred. The channel
capacity will therefore be used efficiently.
5.3.3.1 Addressing
CLDPS addresses a PT through a temporary 8-bit address (PtAddr). A PT obtains its PtAddr
dynamically from a FT at registration. It will be valid throughout the session. If a PT changes
the radio cell it will obtain a new PtAddr.
As there is one FT per radio cell, CLDPS does not specifiy an FT address.
PtAddr is basically different from bus addresses used in bus systems. According to the
system architecture more than one bus ports may be available through a PtAddr, so it is not
a 1:1 correlation between addresses.
The CLDPS firmware implements ethernet interworking. This function manages mapping
between ethernet MAC address and the corresponding temporary PtAddr.
5.3.3.2 Functionality
CLDPS processes datagrams with variable lengths of up to 1600 bytes.
The datagram’s integrity will remain during transmission, i.e. the receiver side will output the
complete datagram.
Datagrams may be transferred as either unicast or multicast. A unicast datagram is directed
to a specific port whereas a multicast addresses all bus ports.
There is no direct communication between PTs. In case a PT sends a multicast datagram or
an unicast datagram to a specific PT, the datagrams are first transmitted to the FT which
relays them to their destination.
Internally protocols for error correction are used in order to reliably detect transmission errors
and solve this condition by re-transmission. The application may assume that the data
delivered by CLDPS are correct. However, complete loss of datagrams is possible. The
order of unicast datagrams to and from any PT will remain.
5.3.3.3 Registration to a Base Station
The PT will automatically register to an available FT under control of CLDPS. Of course it
must first be subscribed to the FT(s) during configuration.