7 Error handling

08.583GPPBase Station Controler - Base Transceiver Station (BCS-BTS) Interface Layer 3 SpecificationRelease 1999TS

7.1 General

The procedures specified above apply to those messages which pass the checks described below.

The behaviour of BSC in erroneous cases is implementation dependent.

The behaviour of BTS in erroneous cases is to ignore the message and to send a report to BSC. The report can be sent in either of the following messages:

– CHANNEL ACTIVATION NACK in connection with channel activations;

– MODE MODIFY NACK in connection with a channel mode change;

– ERROR REPORT in other cases.

For procedures controlled by the BSC, and in particular procedures where the BSC sends a request for resources at the BTS and waits for an acknowledge, the implementation in the BSC must provide means for avoiding deadlock situations at the BTS as e.g. hanging resources.

7.2 Message discriminator error

A message with a non-specified message discriminator is erroneous.

7.3 Message type error

A message with a non-specified message type is considered correct, but is ignored by BTS.

7.4 Message sequence error

A message with an existing message type which is not possible according to the specification and to the state of the BTS is erroneous.

7.5 General information element errors

This category includes:

– Information element out of sequence;

– Abnormally duplicated element;

– Missing element.

A message with such an error is erroneous.

7.6 Mandatory information element errors

This includes:

a) Non-existing element type.

b) Information length error.

c) Content which does not comply with the specification (value reserved for future use is considered as case d)).

d) Value indicated as reserved for future use.

e) Bits reserved for future use not set to 0.

f) Content complying with specification but incompatible with the state.

g) Content complying with the specification but inconsistent.

All cases except e) are considered erroneous.

In case e), BTS simply ignores the reserved (RFU) bits.

7.7 Optional information element errors

The same categories of errors as in previous subclause apply.

In cases other than b), e), f) and g), BTS ignores the element and processes the rest of the message.

Cases b), f) and g) are considered erroneous.

In case e), BTS ignores the reserved (RFU) bits.

7.8 Conditional information element errors

The same categories of errors as in subclause 7.6 apply.

If the conditions for presence of the element are met, the same erroneous cases as in subclause 7.6 apply.

If the conditions for presence of the element are not met, the same erroneous cases as in subclause 7.7 apply.