Method and system for random access interference mitigation in heterogeneous cellular networks
First Claim
1. A method at a user equipment operating in a heterogeneous wireless network having a plurality of access nodes comprising a first access node and at least one low power access node, Wherein the user equipment is configured to receive stronger downlink signals from the first access node than from the at least one low power access node, the method comprising:
- determining, by the user equipment, whether a low power access node is better for uplink data transmission than the first access node, the low power access node having lower transmit power than the first access node and being within the coverage area of the first access node;
identifying, by the user equipment, one random access preamble out of a plurality of sets of random access preambles, wherein the plurality of sets includes a first set of random access preambles used for sending to the first access node, and a second set of random access preambles used for sending to the low power access node; and
if the low power access node is better for uplink data transmission, sending from the user equipment to the low power access node, a random access preamble belonging to the first set of random access preambles for sending to the first access node.
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Accused Products
Abstract
Methods and systems at a user equipment, low power access node and first access node operating in a wireless network having a plurality of access nodes comprising a first access node and at least one low power access node having lower transmit power than the first access node, wherein the user equipment receives stronger downlink signals from the first access node than from the at least one low power access node, the method at the user equipment determining, by the user equipment, whether a low power access node is better for uplink data transmission than the first access node; and if the low power access node is better for uplink data transmission, sending from the user equipment to the low power access node, a random access preamble directed to the first access node.
16 Citations
28 Claims
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1. A method at a user equipment operating in a heterogeneous wireless network having a plurality of access nodes comprising a first access node and at least one low power access node, Wherein the user equipment is configured to receive stronger downlink signals from the first access node than from the at least one low power access node, the method comprising:
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determining, by the user equipment, whether a low power access node is better for uplink data transmission than the first access node, the low power access node having lower transmit power than the first access node and being within the coverage area of the first access node; identifying, by the user equipment, one random access preamble out of a plurality of sets of random access preambles, wherein the plurality of sets includes a first set of random access preambles used for sending to the first access node, and a second set of random access preambles used for sending to the low power access node; and if the low power access node is better for uplink data transmission, sending from the user equipment to the low power access node, a random access preamble belonging to the first set of random access preambles for sending to the first access node. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A user equipment operating in a heterogeneous wireless network having a plurality of access nodes comprising a first access node and at least one low power access node, wherein the user equipment receives stronger downlink signals from the first access node than from the at least one low power access node, the user equipment comprising:
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a processor; and a communications subsystem, wherein the processor and communications subsystem cooperate to; determine whether a low power access node is better for uplink data transmission than the first access node, the low power access node having lower transmit power than the first access node and being within the coverage area of the first access node; identify one random access preamble out of a plurality of sets of random access preambles, wherein the plurality of sets includes a first set of random access preambles used for sending to the first access node, and a second set of random access preambles used for sending to the low power access node; and if the low power access node is better for uplink data transmission, send to the low power access node, a random access preamble belonging to the first set of random access preambles for sending to the first access node.
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11. A method at a low power access node operating in a heterogeneous wireless network having a plurality of access nodes comprising a first access node and at least one low power access node, the method comprising:
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determining, at the low power access node, a presence of a first random access preamble, wherein the first random access preamble is of a first set of preambles at a first set of physical random access channel (‘
PRACH’
) opportunities rather than from a second set of preambles at a second set of PRACH opportunities, wherein the first set of preambles is configured for the first access node and the second set of preambles is configured for the low power access node, the low power access node having lower transmit power than the first access node and being within the coverage area of the first access node; andforwarding a report of the first random access preamble to the first access node. - View Dependent Claims (12, 13, 14, 15)
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16. A low power access node operating in a heterogeneous wireless network having a plurality of access nodes comprising a first access node and at least one low power access node, the low power access node comprising:
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a processor; and a communications subsystem, wherein the processor and communications subsystem cooperate to; determine, at the low power access node, a presence of a first random access preamble, wherein the first random access preamble is of a first set of preambles at a first set of physical random access channel (‘
PRACH’
) opportunities rather than from a second set of preambles at a second set of PRACH opportunities, wherein the first set of preambles is configured for the first access node and the second set of preambles is configured for the low power access node, the low power access node having lower transmit power than the first access node and being within the coverage area of the first access node; andforward a report of the first random access preamble to the first access node.
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17. A method at a first access node operating in a heterogeneous wireless network having a plurality of access nodes comprising the first access node and at least one low power access node, the method comprising:
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signalling first set and a second set of random access preambles and a first set and a second set of random access opportunities, wherein a first preamble of the first set of random access preambles is from a user equipment receiving downlink signals from the first access node to send a random access preamble to the first access node over the first set of random access opportunities and a second preamble of the second set of random access preambles is intended for a user equipment receiving downlink signals from the first access node to send a random access preamble to a lower power node over the second set of random access opportunities;
detecting a presence of a first preamble of the first set of random access preambles over the first set of random access opportunities;receiving at least a physical random access channel (‘
PRACH’
) detection report from at least one low power access node, the low power access node having lower transmit power than the first access node and being within the coverage area of the first access node, the report containing at least one of;
a random access preamble identifier indicating a second preamble of the second set of random access preambles detected over the second preamble opportunities, a preamble resource identifier indicating the time-frequency resource over which the preamble was detected, a detected second time of arrival, a second time offset, or a second uplink power adjustment; andsending a random access response for each of at least one of the first preamble or the second preamble detected by the first access node or received in the report from the at least one low power access node. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
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28. A first access node operating in a heterogeneous wireless network having a plurality of access nodes comprising the first access node and at least one low power access node, the first access node comprising:
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a processor; and a communications subsystem, wherein the processor and communications subsystem cooperate to; signal a first set and a second set of random access preambles and a first set and a second set of random access opportunities, wherein a first preamble of the first set of random access preambles is from a user equipment receiving downlink signals from the first access node to send a random access preamble to the first access node over the first set of random access opportunities and a second preamble of the second set of random access preambles is intended for a user equipment receiving downlink signals from the first access node to send a random access preamble to a lower power node over the second set of random access opportunities; detect a presence of a first preamble of the first set of random access preambles over the first set of random access opportunities; receive at least a physical random access channel (‘
PRACH’
) detection report from at least one low power access node, the low power access node having lower transmit power than the first access node and being within the coverage area of the first access node, the report containing at least one of;
a random access preamble identifier indicating a second preamble of the second set of random access preambles detected over the second preamble opportunities, a preamble resource identifier indicating the time-frequency resource over which the preamble was detected, a detected second time of arrival, a second time offset, or a second uplink power adjustment; andsend a random access response for each of at least one of the first preamble or the second preamble detected by the first access node or received in the report from the at least one low power access node.
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Specification