Phase shifted time slice transmission to improve handover
First Claim
1. A method of receiving a plurality of data packets from a wireless system by a wireless terminal, the wireless system comprising a first base station and a second base station, the method comprising the steps of:
- (a) determining a first amount of phase shift that is associated with a current first channel burst that comprises a first group of data packets, wherein the first amount of phase shift is associated with the first base station and wherein the first amount of phase shift is different from a second phase shift that is associated with the second base station; and
(b) receiving the current first channel burst in accordance with the first amount of phase shift;
(c) determining the second amount of phase shift that is associated with the second base station;
(d) measuring a first signal characteristic of a first signal that is transmitted by the first base station;
(e) measuring a second characteristic of a second signal that is transmitted by the second base station; and
(f) if the first signal characteristic satisfies a first predefined criterion and if the second signal characteristic satisfies a second predefined criterion, switching reception from the first base station to the second base station; and
(g) in response to step (f), receiving a second channel burst from the second base station in accordance with the second amount of phase shift, wherein the second channel burst comprises a second group of data packets.
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Abstract
The present invention provides methods and apparatus for a wireless system broadcasting a plurality of data packets to at least one wireless terminal. The wireless system comprises a plurality of base stations that interfaces to a backbone network in order to receive the plurality of data packets from a service source. Data packets are sent to a wireless terminal by a first base station transmitting a first channel burst and by a second base station transmitting a second channel burst, in which corresponding time offsets of the channel bursts, as characterized by amounts phase shifts, are different. Consequently, when the wireless terminal executes a handover from the first base station to the second base station, a probability that some of the data packets are lost, as result of practical network considerations, is reduced.
71 Citations
25 Claims
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1. A method of receiving a plurality of data packets from a wireless system by a wireless terminal, the wireless system comprising a first base station and a second base station, the method comprising the steps of:
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(a) determining a first amount of phase shift that is associated with a current first channel burst that comprises a first group of data packets, wherein the first amount of phase shift is associated with the first base station and wherein the first amount of phase shift is different from a second phase shift that is associated with the second base station; and (b) receiving the current first channel burst in accordance with the first amount of phase shift; (c) determining the second amount of phase shift that is associated with the second base station; (d) measuring a first signal characteristic of a first signal that is transmitted by the first base station; (e) measuring a second characteristic of a second signal that is transmitted by the second base station; and (f) if the first signal characteristic satisfies a first predefined criterion and if the second signal characteristic satisfies a second predefined criterion, switching reception from the first base station to the second base station; and (g) in response to step (f), receiving a second channel burst from the second base station in accordance with the second amount of phase shift, wherein the second channel burst comprises a second group of data packets. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. A wireless terminal that receives a plurality of data packets from a wireless system, the wireless system comprising a first base station and a second base station, comprising:
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a storage buffer; a timing module; a radio module that communicates with the wireless system over a radio channel; a processor that receives an indication from the timing module that a current first channel burst is being transmitted, wherein the current first channel burst contains a first group of data packets, and that stores the first group of data packets into the storage buffer, the processor configured to perform the steps of; (a) determining a first amount of phase shift that is associated with the current first channel burst that comprises the first group of data packets, wherein the first amount of phase shift is associated with the first base station and wherein the first amount of phase shift is different from a second phase shift that is associated with the second base station; and (b) receiving the current first channel burst in accordance with the first amount of phase shift; (c) determining the second amount of phase shift that is associated with the second base station; (d) measuring a first signal characteristic of a first signal that is transmitted by the first base station; (e) measuring a second characteristic of a second signal that is transmitted by the second base station; (f) if the first signal characteristic satisfies a first predefined criterion and if the second signal characteristic satisfies a second predefined criterion, switching reception from the first base station to the second base station; and (g) in response to step (f), receiving a second channel burst from the second base station in accordance with the second amount of phase shift, wherein the second channel burst comprises a second group of data packets. - View Dependent Claims (19, 20, 21, 22, 23)
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24. A method for broadcasting a plurality of data packets by a wireless system to a wireless terminal, the wireless system comprising a first base station and a second base station, the method comprising the steps of:
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(a) mapping a first group of data packets to a current first channel burst; (b) determining a first amount of phase shift that corresponds to the current first channel burst, wherein the first amount of phase shift is different from a second phase shift that is associated with the second base station;
p1 (c) transmitting, at a same time, the current first channel burst that corresponds to the first amount of phase shift to a plurality of wireless terminals, the current first channel burst supporting a digital broadband broadcasting service to the plurality of wireless terminals;(d) receiving, by the first base station, a first signal characteristic that is indicative of a first signal that is transmitted by the first base station and that is measured by the wireless terminal and a second signal characteristic that is indicative of a second signal that is transmitted by the second base station and that is measured by the wireless terminal; (e) determining whether the wireless terminal should be served by the second base station in accordance with the first and second signal characteristics; and (f) sending an instruction to the wireless terminal to switch base stations in response to step (e).
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25. A method of receiving a plurality of data packets from a wireless system by a wireless terminal, the wireless system comprising a first base station and a second base station, the method comprising the steps of:
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(a) determining a first amount of phase shift that is associated with a first channel burst that comprises a first group of data packets, wherein the first group of data packets is associated with a digital broadband broadcasting service and wherein the first amount of phase shift is associated with the first base station and the first data service; (b) receiving the first channel burst in accordance with the first amount of phase shift; (c) determining a second amount of phase shift that is associated with the second base station and the digital broadband broadcasting service; (d) measuring a first signal characteristic of a first signal that is transmitted by the first base station; (e) measuring a second characteristic of a second signal that is transmitted by the second base station; (f) if the first signal characteristic satisfies a first predefined criterion and if the second signal characteristic satisfies a second predefined criterion, switching reception from the first base station to the second base station; (g) in response to step (f), receiving a second channel burst from the second base station in accordance with the second amount of phase shift, wherein the second channel burst comprises a second group of data packets that is associated with the digital broadband broadcasting service; (h) if numbering of data packets is not consecutive, rearranging data packets of the second group of data packets so that the numbering is consecutive; and (i) if duplicate data packets are received within the second group of data packets, discarding one of the duplicate data packets.
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Specification