Telecommunications – Transmitter and receiver at separate stations – Plural transmitters or receivers
Reexamination Certificate
2000-12-12
2003-09-23
Maung, Nay (Department: 2684)
Telecommunications
Transmitter and receiver at separate stations
Plural transmitters or receivers
C455S069000, C455S068000, C455S070000
Reexamination Certificate
active
06625466
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to a method and to a system for regulating the transmission power of a mobile station of a mobile radiotelephone system in which information are transmitted in different carrier frequencies with a frequency hopping method.
2. Description of the Related Art
In order to replace the various analog and digital standards that exist in Europe, the DECT (digital enhanced cordless communication) standard was passed in the early ‘90’s. It is the first common European standard for cordless telecommunication. A DECT network is a micro-cellular, digital mobile radiotelephone network for high subscriber densities and is mainly designed for use in buildings. Use of the DECT standard, however, is likewise possible outside of buildings. The capacity of the DECT network of about 10,000 subscribers per square kilometer makes the cordless standard into an ideal access technology for network operators. According to the DECT standard, the transmission of data signals is also possible in addition to the transmission of speech. Thus, cordless data networks can also be constructed on a DECT basis.
The DECT standard is explained in greater detail below with reference to
FIG. 2. A
digital, cordless telecommunication system was standardized for Europe under the name DECT. In combination with the switching function of a telecommunication system, this system is thus suitable for the mobile telephone and data traffic in an office building or on a corporate campus. The DECT functions supplement a telecommunication system and thus turn a switch into the fixed station FS of the cordless telecommunication system. Digital radio connections between the fixed station FS and the maximum of 120 mobile stations MS can thus be set up, monitored and controlled on up to 120 channels.
Transmission on a maximum often different carrier frequencies (carriers) is carried out in the frequency range of 1.88 GHz to 1.9 GHz. This frequency-division multiplex method is referred to as FDMA (frequency division multiple access).
Respectively twelve timeslots are transmitted in chronological succession in the uplink and in the downlink in the time-division multiplex method TDMA (time division multiple access) on each of the ten carrier frequencies. Thus 120 channels derive for the cordless telecommunication according to the DECT standard for ten carrier frequencies, each having twelve timeslots in the uplink and in the downlink. Since, for example, one channel is required for each voice connection, 120 connections to a maximum of 120 mobile stations MS derive. Alternating mode (duplex, TTD) is employed on the carriers. After twelve channels (channels
1
-
12
) have been sent by the fixed station, it switches to reception and receives twelve channels (channels
13
-
24
) from at least one mobile station in the opposite direction.
A time-division multiplex frame is thus composed of 24 channels (see FIG.
2
). Channel
1
through channel
12
are transmitted from the fixed station FS to the mobile stations MS, whereas channel
13
through channel
24
are transmitted in the opposite direction from the mobile stations MS to the fixed station FS. The frame duration is 10 ms. 320 bits of information (for example, speech) and 104 bits of control data (e.g., synchronization, signalling and error monitoring data) are transmitted in this time. The payload bit rate for a subscriber (channel) derives from the 320 bits of information within 10 ms, which translate to 32 kilobits per second.
Integrated components that convert the DECT functions have been developed for fixed and mobile stations. The fixed station and the mobile station perform similar functions. One of the integrated modules is the RF module, i.e., the module that implements the actual function of receiving and transmitting in the RF range.
It is known to employ “fast hopping” RF modules, i.e., RF modules that can implement a change of the carrier frequency from one timeslot or, channel to the next. However, these fast hopping RF modules are very complex and expensive, so usually “slow hopping-RF modules are employed in practice, i.e., modules that require a certain time for changing the carrier frequency. In practice, the time span that the slow hopping RF module requires for the change of the carrier frequency essentially corresponds to the time span of a time slot. This means that an inactive time slot (blind slot) in which no data can be transmitted must follow each active time slot, i.e., each slot in which are transmitted. This means that only six connections can be implemented in practice on a carrier frequency in the DECT standard instead of the twelve connections that are possible.
A DECT channel is defined by its time slot and its carrier frequency. According to the DECT standard, the organization of the reemployment of physical channels ensues with a dynamic channel selection. A complicated frequency planning, as in cellular systems, is thus superfluous. For a connection setup, the signal levels of all channels are continuously measured and the malfunction-free channels are administered in a channel list (channel map). During a connection, the signal levels of all channels as well as the reception quality continue to be measured. When this monitoring shows that the channel employed at the moment was transmitted on a carrier frequency that was disturbed (due, for example, to the influence of a transmission on the same carrier frequency from or to a different fixed station), a different carrier frequency that is entered as disturbance-free in the in the channel list is automatically selected for the next active time slot.
As an alternative, a “frequency hopping” method in which the carrier frequency is changed after a predetermined time span, for example, one frame of the transmission, can also be employed.
For countries outside of Europe, the DECT standard may have to be modified and adapted to the local conditions. In the USA, for example, the transmission cannot ensue in the normal DECT range between 1.88 and 1.90 GHz; rather, the generally accessible 2.4 GHz ISM (industrial, scientific, medical) band is available. Furthermore, changes would have to be undertaken for adaptation to the national regulations such as the American rule FCC part
15
which describes the transmission methods, transmission powers and the available bandwidth allowed for the air interface.
In the DECT standard, each time slot contains another 104 bits required for the signal transmission in addition to the aforementioned 320 information bits as well as 56 bits of a guard field, so that each time slot contains a total of 480 bits, permitting a data rate of (24×480 bits)/10 ms=1,152,000 bits/s. This high data rate is not meaningful in the American ISM band since too great a bandwidth would be required per usable channel. Despite these rules, optimally unmodified component parts developed for the DECT standard such as the baseband controller should, for cost reasons, continue to be useable despite these rules.
Since, further, mobile stations are usually battery/storage cell-operated, the energy they consume during operation should be as low as possible in order to enable long operating times.
ETS 300 578: March 1995 (GSM 5.08 version 4.12.0) discloses a system in which a change of the transmission signal power of a mobile part is initiated by exceeding a upward or, downward limit of a signal level threshold by a plurality of values of a signal level measured by the base station as well as exceeding an upward or downward transgression of a quality threshold by a plurality of values of a quality parameter value measured by the base station.
For the mobile radio transmitter/receiver, particularly a mobile part, of a cordless telecommunication system according to German patent document DE 44 26 255 A1, the mobile part—regardless of a reception level evaluation by the base station—should be independently in the position to regulate the transmission power in order to reduce the power or, energy consumpt
Dicker Olaf
Kockmann Jürgen
Bell Boyd & Lloyd LLC
Gantt Alan T.
Maung Nay
Siemens Aktiengesellschaft
LandOfFree
Method and system for regulating the transmission power of a... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and system for regulating the transmission power of a..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and system for regulating the transmission power of a... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3044916