Telecommunications – Radiotelephone system – Including private cordless extension system
Reexamination Certificate
2001-02-07
2004-07-13
Vo, Nguyen T. (Department: 2682)
Telecommunications
Radiotelephone system
Including private cordless extension system
C455S550100
Reexamination Certificate
active
06763239
ABSTRACT:
The invention relates to a control unit for a terminal of a digital, cordless telecommunication system for delivering control signals to further units of the terminal, as well as to a method for such a control unit.
The communication between the terminals of a digital, cordless telecommunication system, notably between handsets and base stations, takes place via a radio control unit which is connected to an antenna in each terminal. The typical construction of a terminal is shown in FIG.
1
. The radio control unit
2
therein is controlled by a control unit
1
(BMC: Burst Mode Controller). The control unit
1
is responsible for the time-critical processing of the data to be transmitted and received. Moreover, it outputs control signals via the control leads of the radio control unit
2
. The control unit
1
itself is controlled by a microcontroller
3
which carries out the protocol functions and other, less time-critical functions. In addition, a further unit
4
may be provided for some systems, for example, for systems involving the transmission of audio data, which further unit carries out digital signal processing of the data to be transmitted or of the received data. Finally, the microcontroller
3
and the unit
4
for the digital signal processing have access to the applications
5
of the terminal.
FIG. 2
shows the construction of the control device
1
in greater detail.
The main components of the control device
1
are formed by a control unit
10
and a data processing unit
11
. The control unit
10
receives commands
20
from the microcontroller
3
; in conformity therewith it controls the output of control signals
22
, via control leads, to the radio control unit
2
and generates and outputs control signals
23
for the data processing unit
11
. Moreover, the data processing unit
11
supplies the control unit
10
with feedback information
24
which can also influence the control behavior of the control unit
10
. The data processing unit
11
itself is used to perform given functions on the data bits
27
,
29
received and the data bits
26
,
28
to be transmitted, for example, encryption (scrambling)
12
,
14
, or generating a test sum
13
(CRC: Cyclic Redundancy Code). In a terminal of a digital cordless telecommunication system, for example, DECT, the data to be transmitted and received must be processed in real time. The control unit
10
and the data processing unit
11
can both apply status information
21
,
25
to the microcontroller
3
.
The control unit of a control device is typically implemented as a hardware automatic. Therefore, problems are encountered as soon as a modification of the output of the control signals is required. For example, any change of format of the data packets necessitates a new design of the control unit, even when the same data processing functions are to be used and merely a different bit timing is desired. Similarly, the addition or removal of data processing functions as well as a modification of the specification of the radio interface or the timing for the radio control signals also necessitate a new design of the control unit. Consequently, the hardware of a control unit for a given telecommunication standard, for example DECT, can be used for other telecommunication systems, for example the United States ISM band system, only at the expense of major adaptations.
From GSM, however, a baseband control unit is known in which the hardware implemented automatic for the output of control signals is dispensed with. The unit used instead is illustrated in FIG.
3
: a microcontroller writes values for an event containing control signals into a control signal register
30
and writes the values for an instant at which the control signals of the event are to be output via the control lines
36
connected to the control signal register
30
in an instant register
31
. A comparator
32
continuously compares the instant of the instant register
31
with the time delivered by a timer
32
. The timer
32
is controlled by a local clock generator
35
. In the case of correspondence, the event is output from the control signal register
30
via an output register
34
and the control lines
36
. The control lines may supply, for example, a radio control unit with control signals
38
and also apply control signals
37
to a data processing unit.
The time settings and the occupancy of the control lines thus can be selected completely at random, because the tasks of the hardware automatic were transferred to the software. Because of the use of the registers it is not necessary either for the software to imitate the actions of the hardware automatic bit by bit.
This offers an advantage, for example, when the format of data packets changes. Because the instants for transferring control signals from the control unit to the data processing unit are preset by the software, a change of format can be dealt with by way of a software modification which is far less intricate than a new design of the hardware. The addition or removal of functions of the data processing unit can also be realized by simple changes in the allocation of the individual bits of the registers to the control lines from the control unit to the data processing unit. Newly allocated significance contents and changed output times for the control lines can thus be maintained by way of pure software modification. The significance contents, the timing and the levels of the radio control signals can also be completely preset by the software, so that modifications are also possible for the radio interface without directly necessitating a new design of the hardware.
An appropriate proposal for a GSM mobile radio apparatus can be found, for example in the publication DE 197 47 275 A1.
The control units that are known from the GSM application, however, cannot be simply transferred to applications in the digital, cordless field. For example, applications such as DECT have a bit rate of 1152 kbit/s which is significantly higher than that of GSM in which the bit rate is 270 kbit/s. Moreover, DECT requires the simultaneous support of a plurality of connections. This leads to a significant amount of software processing and to real-time requirements that can hardly be met at present. For example, in the worst case a reaction time of less than the time of a bit, so less than 0.87 &mgr;s, is required. Because of the need for a minimum delay during the processing in cordless systems connected to PSTN (Public Switch Telephone Networks), on the other hand “off-line” processing of the data received, so processing not in real time, is not possible. Finally, processing steps such as encryption and checking of a test sum etc. must be performed on the data received immediately and with the timing of the signal data received. Therefore, the use of a reference time which is dependent on the local system time (as used for GSM) is not possible either.
It is an object of the invention to provide a flexible and energy-saving control unit for a terminal of a digital, cordless telecommunication system for delivering control signals to further units of the terminal. It is another object of the invention to provide a method enabling the use of a flexible and energy-saving control unit for a terminal of a cordless telecommunication system.
The object according to the invention is achieved by means of a control unit.
The object is also achieved by means of a method of using the control unit.
The control unit according to the invention and the method according to the invention are based on software control with adequate hardware support, resulting in a high flexibility while ensuring at the same time that no excessive requirements are imposed on the microcontroller performance.
The invention enables adaptations to changing secondary conditions without necessitating a new design of the hardware. It is thus simply possible to perform an adaptation to applications of different systems by appropriately adapting the events and instants delivered to the register arrays by the microcontroller. Similar
Huber Holger
Stobart Christopher
Behulu Alemayehu
Koninklijke Philips Electronics , N.V.
Vo Nguyen T.
Waxler Aaron
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