US6701129B1
Expired / Lapsed
US
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Receiver based adaptive modulation scheme
Assignee: Apple Inc
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Filing: 2000-09-27
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Granted: 2004-03-02
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Expires: 2020-09-27
Abstract
Abstract A method is provided for adapting modulation schemes to changing channel quality with reduced overhead signalling. A remote unit measures the channel quality of a radio channel along which a signal from a base station reached the remote unit. Based on the channel quality, the remote unit determines a desired set of transmission parameters from a list of sets of transmission parameters. The remote unit determines a difference in position within the list between the current set of transmission parameters and the desired set of transmission parameters. The remote unit transmits the difference to the base station, which selects a new set of transmission parameters using the current set of transmission parameters and the difference. The method requires little signalling between the remote unit and the base station, and is particularly beneficial in communication systems employing many sub-carriers, such as OFDM systems.
Inventors
- 👤 Bassam M. Hashem
- 👤 Shalini S. Periyalwar
- 👤 David G. Steer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:11
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/0001; H04L1/0023; H04L1/0028; H04L1/0029; H04L1/0025; H04L5/00; H04L5/003; H04L5/0044; H04L1/0002; H04L1/0003; H04L1/0009; H04W; H04W24/00; H04W28/00; H04W28/02; H04W28/06; H04W28/16; H04W28/18
Claims Analysis
Total Claims: 56
Claim 1
Independent Claim
173 words
A method of adapting a current Link Mode (LM) in a radio communication system, a LM being a set of at least one transmission parameter, the communication system including a base station which transmits a signal to a remote unit using the current LM, the method comprising the steps of: storing a sequence of allowed LMs at the base station and at the remote unit, each LM having a sequential position within the sequence; at the remote unit, determining a channel quality of the signal; at the remote unit, determining a desired LM from amongst the sequence of allowed LMs based on the channel quality; at the remote unit, determining a sequential difference defined as a difference between the sequential position of the current LM and the sequential position of the desired LM; transmitting the sequential difference from the remote unit to the base station; at the remote unit, setting a new current LM to be the desired LM; and at the base station, setting the new current LM using the sequential difference.
Claim 2
Independent Claim
173 words
A method of adapting a current Link Mode (LM) in a radio communication system, a LM being a set of at least one transmission parameter, the communication system including a base station which transmits a signal to a remote unit using the current LM, the method comprising the steps of: storing a sequence of allowed LMs at the base station and at the remote unit, each LM having a sequential position within the sequence; at the remote unit, determining a channel quality of the signal; at the remote unit, determining a desired LM from amongst the sequence of allowed LMs based on the channel quality; at the remote unit, determining a sequential difference defined as a difference between the sequential position of the current LM and the sequential position of the desired LM; transmitting the sequential difference from the remote unit to the base station; at the remote unit, setting a new current LM to be the desired LM; and at the base station, setting the new current LM using the sequential difference.
Claim 3
Dependent Claim
28 words
The method of claim 1 further comprising the step of transmitting the desired LM from the remote unit to the base station if a predefined condition is met.
Claim 4
Dependent Claim
15 words
The method of claim 1 wherein the channel quality is a signal to interference ratio.
Claim 5
Dependent Claim
16 words
The method of claim 1 wherein the channel quality is determined from the transmission error rate.
Claim 6
Dependent Claim
16 words
The method of claim 1 wherein the at least one transmission parameter includes a modulation scheme.
Claim 7
Dependent Claim
16 words
The method of claim 1 wherein the at least one transmission parameter includes a coding rate.
Claim 8
Dependent Claim
16 words
The method of claim 6 wherein the at least one transmission parameter includes a modulation scheme.
Claim 9
Dependent Claim
16 words
The method of claim 1 wherein the at least one transmission parameter includes antenna directional coefficients.
Claim 10
Dependent Claim
20 words
The method of claim 1 wherein the at least one transmission parameter includes space-time coding coefficients for multiple antenna systems.
Claim 11
Dependent Claim
154 words
The method of claim 1 wherein the signal is transmitted over a plurality of sub-carriers, each sub-carrier belonging to one of a plurality of groups of sub-carriers, each group of sub-carriers having a current LM, and wherein: the step of determining a channel quality determines a channel quality for each sub-carrier the step of determining a desired LM determines a desired LM for at least one group of sub-carriers; the step of determining a sequential difference determines a sequential difference for at least one group of sub-carriers; the step of transmitting the sequential difference transmits a sequential difference for at least one group of sub-carriers; the step of setting a new current LM at the remote unit sets a new current LM for at least one group of sub-carriers; and the step of setting a new current LM at the base station sets a new current LM for at last one group of sub-carriers.
Claim 12
Dependent Claim
35 words
The method of claim 10 further comprising the step of transmitting the desired LM for at least one group of sub-carriers from the remote unit to the base station if a predefined condition is met.
Claim 13
Dependent Claim
18 words
The method of claim 10 wherein the channel quality of each sub-carrier is a signal to interference ratio.
Claim 14
Dependent Claim
107 words
The method of claim 12 wherein the base station transmits a pilot signal over at least one pilot sub-carrier such that the pilot signal is either on or off, the pilot sub-carrier having a signal strength when it is received by the remote unit and a carrier frequency, and the step of determining the signal to interference ratio of a sub-carrier having a carrier frequency closer to the carrier frequency of the pilot sub-carrier than to a carrier frequency of any other pilot sub-carrier calculates a ratio of the signal strength when the pilot signal is on to the signal strength when the pilot signal is off.
Claim 15
Dependent Claim
14 words
The method of claim 13 wherein the communication system employs Orthogonal Frequency Division Multiplexing.
Claim 16
Dependent Claim
16 words
The method of claim 10 wherein each group of sub-carriers contains sub-carriers having contiguous sub-band numbers.
Claim 17
Dependent Claim
14 words
The method of claim 10 wherein each group of sub-carriers contains a single sub-carrier.
Claim 18
Dependent Claim
16 words
The method of claim 10 wherein the at least one transmission parameter includes a modulation scheme.
Claim 19
Dependent Claim
16 words
The method of claim 10 wherein the at least one transmission parameter includes a coding rate.
Claim 20
Dependent Claim
16 words
The method of claim 18 wherein the at least one transmission parameter includes a modulation scheme.
Claim 21
Dependent Claim
14 words
The method of claim 10 wherein the communication system employs Orthogonal Frequency Division Multiplexing.
Claim 22
Dependent Claim
125 words
The method of claim 1 comprising the further steps of: at the remote unit, selecting a packet number of a packet which will arrive at the remote unit after propagation of a return signal to the base station and propagation of a signal to the remote unit; and transmitting the selected packet number from the remote unit to the base station; and wherein the step of setting a new current LM at the remote unit sets a new current LM once the remote unit receives a packet identified by the selected packet number, and wherein the step of setting a new current LM at the base station sets a new current LM once the base station transmits a packet identified by the selected packet number.
Claim 23
Dependent Claim
138 words
A remote unit for a radio communication system, the remote unit including a decoder which decodes a signal received from a base station using a current Link Mode (LM), a LM being a set of at least one transmission parameter, and the remote unit comprising: means for storing a sequence of allowed LMs, each LM having a sequential position within the sequence; means for determining a channel quality of the signal; means for determining a desired LM from amongst the sequence of allowed LMs based on the channel quality; means for determining a sequential difference defined as a difference between the sequential position of the current LM and the sequential position of the desired LM; means for transmitting the sequential difference to the base station; and means for setting a new current LM to be the desired LM.
Claim 24
Dependent Claim
138 words
A remote unit for a radio communication system, the remote unit including a decoder which decodes a signal received from a base station using a current Link Mode (LM), a LM being a set of at least one transmission parameter, and the remote unit comprising: means for storing a sequence of allowed LMs, each LM having a sequential position within the sequence; means for determining a channel quality of the signal; means for determining a desired LM from amongst the sequence of allowed LMs based on the channel quality; means for determining a sequential difference defined as a difference between the sequential position of the current LM and the sequential position of the desired LM; means for transmitting the sequential difference to the base station; and means for setting a new current LM to be the desired LM.
Claim 25
Dependent Claim
27 words
The remote unit of claim 22 further comprising means for transmitting the desired LM to the base station in the event that a predefined condition is met.
Claim 26
Dependent Claim
16 words
The remote unit of claim 22 wherein the channel quality is a signal to interference ratio.
Claim 27
Dependent Claim
17 words
The remote unit of claim 22 wherein the at least one transmission parameter includes a modulation scheme.
Claim 28
Dependent Claim
17 words
The remote unit of claim 22 wherein the at least one transmission parameter includes a coding rate.
Claim 29
Dependent Claim
17 words
The remote unit of claim 26 wherein the at least one transmission parameter includes a modulation scheme.
Claim 30
Dependent Claim
142 words
The remote unit of claim 22 wherein the signal is received over a plurality of sub-carriers, each sub-carrier belonging to one of a plurality of groups of sub-carriers, each group of sub-carriers having a current LM, and wherein: the means for determining a channel quality comprise means for determining a channel quality for each sub-carrier; the means for determining a desired LM comprise means for determining a desired LM for at least one group of sub-carriers the means for determining a sequential difference comprise means for determining a sequential difference for at least one group of sub-carriers; the means for transmitting the sequential difference comprise means for transmitting a sequential difference for at least one group of sub-carriers; and the means for setting a new current LM comprise means for setting a new current LM for at least one group of sub-carriers.
Claim 31
Dependent Claim
30 words
The remote unit of claim 28 further comprising means for transmitting the desired LM for at least one group of sub-carriers in the event that a predefined condition is met.
Claim 32
Dependent Claim
19 words
The remote unit of claim 28 wherein the channel quality of each sub-carrier is a signal to interference ratio.
Claim 33
Dependent Claim
109 words
The remote unit of claim 30 wherein at least one sub-carrier is a pilot sub-carrier which carries a pilot signal, the pilot signal being either on or off, the pilot sub-carrier having a signal strength when it is received by the remote unit and a carrier frequency, and the means for determining a signal to interference ratio of a sub-carrier having a carrier frequency closer to the carrier frequency of the pilot sub-carrier than to a carrier frequency of any other pilot sub-carrier comprise means for calculating a ratio of the signal strength when the pilot signal is on to the signal strength when the pilot signal is off.
Claim 34
Dependent Claim
15 words
The remote unit of claim 31 wherein the communication system employs Orthogonal Frequency Division Multiplexing.
Claim 35
Dependent Claim
17 words
The remote unit of claim 28 wherein each group of sub-carriers contains sub-carriers having contiguous sub-band numbers.
Claim 36
Dependent Claim
15 words
The remote unit of claim 28 wherein each group of sub-carriers contains a single sub-carrier.
Claim 37
Dependent Claim
17 words
The remote unit of claim 28 wherein the at least one transmission parameter includes a modulation scheme.
Claim 38
Dependent Claim
17 words
The remote unit of claim 28 herein the at least one transmission parameter includes a coding rate.
Claim 39
Dependent Claim
17 words
The remote unit of claim 36 wherein the at least one transmission parameter includes a modulation scheme.
Claim 40
Dependent Claim
15 words
The remote unit of claim 28 wherein the communication system employs Orthogonal Frequency Division Multiplexing.
Claim 41
Dependent Claim
108 words
A base station for a radio communication system, the base station transmitting a signal to a remote unit using a current Link Mode (LM), a LM being a set of at least one transmission parameter, the base station comprising: means for maintaining a sequence of allowed LMs, each LM having a sequential position within the sequence; means for receiving from the remote unit a sequential difference defined as a difference between the sequential position of the current LM and the sequential position of a desired LM, the desired LM belonging to the sequence of allowed LMs; and means for setting a new current LM using the sequential difference.
Claim 42
Dependent Claim
108 words
A base station for a radio communication system, the base station transmitting a signal to a remote unit using a current Link Mode (LM), a LM being a set of at least one transmission parameter, the base station comprising: means for maintaining a sequence of allowed LMs, each LM having a sequential position within the sequence; means for receiving from the remote unit a sequential difference defined as a difference between the sequential position of the current LM and the sequential position of a desired LM, the desired LM belonging to the sequence of allowed LMs; and means for setting a new current LM using the sequential difference.
Claim 43
Dependent Claim
37 words
The base station of claim 39 further comprising means for setting a new current LM to be equal to the desired LM in the event that the base station receives the desired LM from the remote unit.
Claim 44
Dependent Claim
17 words
The base station of claim 39 wherein the at least one transmission parameter includes a modulation scheme.
Claim 45
Dependent Claim
17 words
The base station of claim 39 wherein the at least one transmission parameter includes a coding rate.
Claim 46
Dependent Claim
17 words
The base station of claim 42 wherein the at least one transmission parameter includes a modulation scheme.
Claim 47
Dependent Claim
92 words
The base station of claim 39 wherein the signal is transmitted over a plurality of sub-carriers, each sub-carrier belonging to one of a plurality of groups of sub-carriers, each group of sub-carriers having a current LM, and wherein: the means for receiving a sequential difference comprise means for receiving a sequential difference for at least one group of sub-carriers; and the means for setting a new current LM comprise means for setting a new current LM for at least one group of sub-carriers using the sequential difference for that group of sub-carriers.
Claim 48
Dependent Claim
17 words
The base station of claim 44 wherein each group of sub-carriers contains sub-carriers having contiguous sub-band numbers.
Claim 49
Dependent Claim
15 words
The base station of claim 44 wherein each group of sub-carriers contains a single sub-carrier.
Claim 50
Dependent Claim
29 words
The base station of claim 44 wherein the base station transmits a pilot signal over at least one sub-carrier such that the pilot signal is either on or off.
Claim 51
Dependent Claim
15 words
The base station of claim 47 wherein the communication system employs Orthogonal Frequency Division Multiplexing.
Claim 52
Dependent Claim
50 words
The base station of claim 44 further comprising: means for setting a new current LM for at least one group of sub-carriers to be equal to a desired LM for that group of sub-carriers in the event that the base station receives the desired LM for that group of sub-carriers.
Claim 53
Dependent Claim
17 words
The base station of claim 44 wherein the at least one transmission parameter includes a modulation scheme.
Claim 54
Dependent Claim
17 words
The base station of claim 44 wherein the at least one transmission parameter includes a coding rate.
Claim 55
Dependent Claim
17 words
The base station of claim 51 wherein the at least one transmission parameter includes a modulation scheme.
Claim 56
Dependent Claim
15 words
The base station of claim 44 wherein the communication system employs Orthogonal Frequency Division Multiplexing.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2007-03-02 | 2007-09-01 | 2008-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2011-03-02 | 2011-09-01 | 2012-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2015-03-02 | 2015-09-01 | 2016-03-02 | $7700.00 | Window Closed / Lapsed |