Frequency look-ahead and link state history based scheduling in indoor wireless pico-cellular networks
First Claim
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1. A frequency hopping time division duplex indoor wireless communication system comprising:
- a master unit having a processor and a first frequency selection unit for finding a current frequency on which to transmit and receive during a current time slot and at least a second frequency selection unit interfaced with said processor to look ahead at frequencies that are to be used in future time slots; and
a plurality of mobile stations communicating with said master unit.
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Abstract
A method and apparatus of combating the problem of interference in master-slave time division duplex indoor wireless networks based on standards, such as the Bluetooth™ standard, is proposed. The method involves a frequency look-ahead scheme in frequency hopping systems, a scheme of monitoring states of master-slave wireless communication links through values recorded in link history counters, and a scheme of scheduling an appropriate slave unit and choosing a suitable packet size to overcome the effect of interfering sources, if any, in the pico-cell.
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Citations
30 Claims
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1. A frequency hopping time division duplex indoor wireless communication system comprising:
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a master unit having a processor and a first frequency selection unit for finding a current frequency on which to transmit and receive during a current time slot and at least a second frequency selection unit interfaced with said processor to look ahead at frequencies that are to be used in future time slots; and a plurality of mobile stations communicating with said master unit. - View Dependent Claims (2, 3)
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4. A frequency hopping indoor wireless communication system comprising:
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a master unit and a plurality of slave units; said master unit having a plurality of link state counters C(i,j), wherein the condition of wireless links between the master unit and a slave unit are recorded in link state counters provided one for each frequency of communication fj between the master and the slave “
I”
. - View Dependent Claims (5, 6)
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7. A frequency hopping time division duplex master-slave indoor wireless communication system comprising:
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a master unit having a processor and a first frequency selection unit for finding a current frequency on which to transmit and receive during a current time slot and at least a second frequency selection unit interfaced with said processor to select frequencies to be used in future time slots; and a plurality of slave units communicating with said master unit, said master unit having a plurality of link state history counters C(i,j), wherein the link state counters are provided one for each frequency of communication fj between the master and the slave “
i”
, whereina) before transmission to a slave unit, the master unit obtains the frequencies corresponding to time slots which will be encountered in the immediate future, b) if the link state history counter for a scheduled slave unit at an expected transmission frequency indicates that a transmission attempt can be made, the master unit proceeds to transmit to the slave unit at an appropriate packet size, c) the master unit tries to choose another active slave unit, if any, for transmission if the link state history counter for the scheduled slave forbids transmission, d) the master unit records the loss and gain of service by the slave units when transmission to slave units takes place in an order different from the regular scheduling order, and e) if the link state history counter values of all active slave units are above a threshold TTRANSMIT, the master unit chooses a slave unit whose link state history counter has the lowest value, and decides on a packet size of one. - View Dependent Claims (8)
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9. A frequency hopping time division duplex master-slave indoor wireless communication system comprising:
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a master unit and a plurality of slave units, wherein (a) every active slave unit monitors packet transmissions from the master unit and records the number of successful receptions by using goodness counters GC(i,j) for every slave unit “
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with reference to frequency fj,(b) a slave unit increments a goodness counter GC(i,j) when a packet transmitted by the slave unit on frequency fj is successfully acknowledged by the master unit, (c) short-term link history is maintained by periodic transfer of goodness counter values from active slave units to the master unit, (d) the master unit constructs a link state history table of counters after receiving values of goodness counters GC(i,j) from all the slave units and uses this information during a next scheduling period, (e) goodness counters GC(i,j) are reset to zero by slave units after successfully transmitting their values to the master unit, and (f) the goodness counters GC(i,j) are allowed to count up to the maximum value and stay there until reset. - View Dependent Claims (10)
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11. A frequency hopping time division duplex master-slave indoor wireless communication system comprising:
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a master unit and a plurality of slave units, wherein (a) a second level frequency look-ahead is performed by the master unit even before a packet from an addressed slave unit is received, and (b) the second level look-ahead is performed by the master unit to determine the slave units and packet sizes to be used next corresponding to the different sizes of packet that might be transmitted by an addressed slave unit. - View Dependent Claims (12)
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13. A communication device employing a frequency hopping sequence to communicate with other communication devices in a wireless communications system, the device comprising:
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a processor; a first frequency selection unit coupled to the processor for determining a frequency to transmit or receive messages during a current time slot; and a second frequency selection unit coupled to the processor for determining one or more future frequencies to transmit or receive messages during look-ahead time slots. - View Dependent Claims (14, 15)
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16. A wireless communications system having a plurality of communication devices, comprising:
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a link state database for containing values representing link states of the plurality of communication devices; a first communication device for updating the link state database in accordance with condition of messages exchanged between the devices of the plurality of communication devices; and a device selection module having a predetermined rule operative to select a second communication device in accordance with values of the link state of the plurality of communication devices, wherein the first and second communication device exchange messages if the value of the link state between the first and second devices is less than or equal to a predetermined transmission threshold. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. A wireless communications system having a plurality of communication devices, comprising:
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a global link state database for containing values representing link states of the plurality of communication devices; a first communication device having a local link state database, wherein the local link state data database contains values representing link states with a second communication device of the plurality of communication device, wherein the values of link states are updated in accordance with condition of messages exchanged with the second communication device, and wherein the values of link states are transmitted in a predetermined time period; a link state database update module for updating the global link state database with the information received from the first communication device; and a device selection module having a predetermined rule operative to select a second communication device in accordance with the values of link states of the plurality of communication devices, wherein the first and second communication device exchange messages. - View Dependent Claims (26, 27, 28, 29, 30)
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Specification