Telecommunications – Transmitter and receiver at separate stations – Having measuring – testing – or monitoring of system or part
Reexamination Certificate
1998-08-14
2001-03-06
Nguyen, Lee (Department: 2683)
Telecommunications
Transmitter and receiver at separate stations
Having measuring, testing, or monitoring of system or part
C455S063300, C455S067700, C455S067700, C455S423000, C455S454000, C455S446000, C455S448000, C455S449000, C370S445000, C370S446000, C370S447000, C370S448000
Reexamination Certificate
active
06198909
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a communication environment with a plurality of radio systems which have at least one radio station. Before a useful signal is transmitted, the radio station checks whether a certain sub-frequency range in a predefined frequency range is free.
2. Description of the Related Art
From the document “R. O. LaMaire and A. Krishna: On the Advantages and Disadvantages of Some Options for Sharing Etiquettes in the 5.15-5.35 GHz band, 5 GHz Sharing Rules Drafting Committee, SRDC/10.28.96.13B, Nov. 14, 1996” is known a radio system which works in the 5 GHz band according to the LBT method (LBT=Listen Before Talk). Radio stations implementing, for example, a CDMA or TDMA method may occupy a part of a predefined spectrum or of a frequency range. First of all it is then necessary for a radio station to check whether a sub-frequency range is free. This is determined by means of an energy detection in the desired sub-frequency range. If the radio station detects that the certain sub-frequency range is free and thus no other radio station utilizes the certain sub-frequency range for signal transmission, this sub-frequency range is; seized for transmitting useful signals. However, it may happen that two radio stations simultaneously seize the certain sub-frequency range. In that case a proper useful signal transmission cannot take place due to the simultaneous seizure of the sub-frequency range by, for example, two radio stations.
SUMMARY OF THE INVENTION
It is an object of the invention to provide another communication environment with a plurality of radio systems.
The object is achieved in a communication environment with a plurality of radio systems of the type defined in the opening paragraph by the following measures: at least one radio station of a radio system:
in a first phase prior to each transmission of a useful signal, checks whether a certain sub-frequency range in a predefined frequency range for a selected size of a radio propagation area is free,
in a second phase if the certain sub-frequency range for the selected size of the radio propagation area is free, transmits at least two pulses restricted to the certain sub-frequency range at random instants and avoids collisions if another radio system has seized the certain sub-frequency range in an overlapping radio propagation area at the same time, and
in a third phase, if the certain sub-frequency range for the selected size of the radio propagation area is free and no collision can be detected, transmits at least useful signals restricted to the certain sub-frequency range.
In a communication environment with a plurality of radio systems, these radio systems are to share a predefined frequency range for the transmission of useful signals. Such a radio system may be a base radio station with a plurality of mobile stations or, for example, fixed stations of a directional radio system. Before it transmits useful signals, a radio system is first to check for a defmied selected size of its radio propagation area whether the selected sub-frequency range lying inside the predefined frequency range is occupied. After a radio station has detected in a first phase that a sub-frequency range is free, a second phase is proceeded to in which pulses are transmitted by the radio station at random instants. The bandwidth of the pulses is limited and the pulses have an average energy for a defined period of time on the periphery of the radio propagation area by which energy the other radio systems are not subjected to interference when they do not have overlapping radio propagation areas. When the pulses are transmitted, the radio station shows other radio stations that it would like to occupy the sub-frequency range to which the pulse s are limited. If the radio station detects that another radio station having an overlapping radio propagation area also transmits pulses generated in the same manner in this specific subfrequency range, the second phase will be terminated because a collision will be at hand and will be avoided by going back to the first phase. If the radio station detects that the certain sub-frequency range is free, a change is made to the third phase in which the useful signals are transmitted. Thanks to the measures according to the invention collisions may be avoided even when two or more systems have simultaneous access to a sub-frequency range when their radio propagation areas are overlapping.
The size of the radio propagation area of the radio system is at least determined by the radiated energy of one radio station of the radio system. This radio station detects a sub-frequency range as free when, on the one hand, the radiated energy outside its radio propagation area is so weak that another radio system does not cause interference on this radio station and, on the other hand, the radiated energy of another radio system in the radio propagation area does not cause interference in its own radio system.
After the radio station has detected in the first phase that the certain sub-frequency. frequency range in the predefined frequency range for the selected size of a radio propagation area is occupied, the radio station again checks after a period of time determined at random either with a reduced size of the radio propagation area of the radio system or with another subfrequency range.
If during a predefined period of time the average radiated energy of the radio station is smaller than the energy by which the size of the radio propagation area is determined, the radio station transmits pulses in addition to the useful signals in the third phase.
For each radio system to be in a position to carry out a detection process in like manner, at least one radio station of each radio system stores at least in the second phase the average energy for a predefined time period on the periphery of a radio propagation area, of the predefined time period and of the minimum or maximum instant between two successive pulses.
The radio station determining the size of a radio propagation area determines via an estimated or empirically determined formula the average energy to be radiated during a predefined period of time so that the threshold value known to each radio system is found on the periphery of the radio propagation area. In similar manner, the interference energy is detected of a radio station of at least one other radio system.
A radio system may comprise, for example, a base radio station and a plurality of mobile stations. A mobile station can only communicate with other mobile stations or the base radio station of the same radio system when the mobile station is located in the radio propagation area. For this purpose, each radio station (for example, mobile station) of a radio system performs an energy detection. A radio station is provided for communicating with other radio stations of the radio system only when the energy detection proves that the radio station is located in the radio propagation area of the radio system.
The invention also relates to a radio station of a radio system and a method of seizing a sub-frequency range in a predefined frequency range by a radio system belonging to a communication environment.
REFERENCES:
patent: 5042083 (1991-08-01), Ichikawa
patent: 5822682 (1998-10-01), Schroderus et al.
patent: WO9527338 (1995-12-01), None
By R.O. Lamaire et al. On the Advantages and Disadvantages of Some Options for Sharing Etiquettes in the 5.15.35 GHZ Band, GHZ Sharing Rules Drafting Committee, SRDC/10.28.9613B, Nov. 14, 1996, pp. 1-11.
Ferguson Keith
Nguyen Lee
U.S. Philips Corporation
LandOfFree
Communication environment with plurality of radio systems does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Communication environment with plurality of radio systems, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Communication environment with plurality of radio systems will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2530769