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AssigneeMotorola Mobility LLC
InventorsKevin L. Baum, Brian K. Classon, Arvind Krishnamoorthy, Vijay Nangia, Philippe J. Sartori
Estimating the term…
A method and apparatus for performing resource allocation with lower required overhead is provided herein. Resource allocations for data transmissions are chosen in such a way as to provide channel quality information for various parts of the channel bandwidth (frequency selective channel quality information), such as allocating two different resource blocks (on different sets of subcarriers) to a mobile unit for two different transmissions. These data transmissions are used to estimate frequency selective channel quality information, thereby eliminating or greatly reducing the need for channel sounding with a broadband pilot. As a result, the overhead on the uplink of the communication system may be significantly reduced.
A method for a communication unit to obtain a resource assignment from a base station, the method comprising the steps of:
A method for a communication unit to obtain a resource assignment from a base station, the method comprising the steps of:
A method in a base station for assigning resources within a communication channel bandwidth to a communication unit for transmission by the communication unit, the method comprising the steps of:
An apparatus in a base station comprising:
A method for assigning resources to a communication unit, the method comprising the steps of:
Dependencies are inferred from the claim text.
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Devices specially adapted for wireless communication networks
Time-frequency: the frequencies being orthogonal, e.g. OFDM or DMT
Inter-user or inter-terminal allocation: frequency-contiguous, i.e. with no allocation of frequencies for one user or terminal between the…
Arrangements for allocating sub-channels of the transmission path: allocation of pilot signals, i.e. of signals known to the receiver
About 4 years 5 months of term left · ends 7 Apr 2031 (estimated)
The present invention relates generally to communication channel resource allocation and in particular to a method and apparatus for performing frequency semi-selective resource allocation.
It is well known that orthogonal frequency division multiplexed (OFDM) systems divide a channel bandwidth into several narrowband subcarriers. Many modern OFDM system proposals include the capability to support frequency-selective (FS) resource allocation. During frequency-selective resource allocation, the channel bandwidth is divided into several sub-bands, which may be called tiles or resource blocks. Each resource block is used for a particular transmission over a particular time interval, and includes several adjacent OFDM subcarriers and spans multiple OFDM symbol periods. For example, a resource block in an OFDM system with a 15 kHz subcarrier spacing and a 4.76 us cyclic prefix length could be defined as containing 12 adjacent subcarriers (˜180 kHz), and the minimum time that a resource block can be assigned for could be seven OFDM symbol periods (˜0.5 msec).
A Discrete Fourier Transform (DFT) pre-coder can be applied to data prior to mapping the data onto the OFDM subcarriers. Such a modulation scheme is known as DFT-spread OFDM, or DFT-SOFDM. DFT-SOFDM can use resource blocks for transmission, similar to plain OFDM.
FIG. 1 is a block diagram of a communication system.
FIG. 2 illustrates a wideband channel divided into many narrow frequency bands.
FIG. 3 illustrates the two-dimensional nature of OFDM resource allocation.
In order to address the above-mentioned need, a method and apparatus for performing resource allocation with lower required overhead is provided herein. More particularly, a hybrid approach to obtaining channel quality information and to resource allocation is provided and referred to as frequency semi-selective (FSS) resource allocation, or FSS-RA. FSS-RA obtains some of the advantages of frequency selective (FS) allocation, such as high performance due to transmission on a part of the channel bandwidth having higher quality, and some of the advantages of frequency non-selective (FNS) allocation, such as low overhead and robustness to channel variations due to Doppler. The proposed FSS-RA scheme does not require channel sounding overhead. However, channel sounding may be used advantageously with the invention for some conditions, such as at the start of a series of transmissions by a mobile unit, in order to provide initial channel quality information.
For FSS-RA, resource allocations for data transmissions are chosen in such a way as to provide channel quality information for various parts of the channel bandwidth (frequency selective channel quality information), such as allocating two different resource blocks (on different sets of subcarriers) to a mobile unit for two different transmissions. These data transmissions are used to estimate frequency selective channel quality information, thereby eliminating or greatly reducing the need for channel sounding with a broadband pilot. As a result, the overhead on the uplink of the communication system may be significantly reduced.
The present invention encompasses a method for assigning resources to a communication unit for transmission by the communication unit. The method comprises the steps of receiving a first transmission from the communication unit, where the first transmission comprises data, and where the first transmission occupies only a first portion of the communication channel bandwidth. A channel quality is estimated for a first set of candidate time-frequency resources based on the received first transmission, and a second transmission is received from the communication unit. The second transmission comprises data, and occupies only a second portion of the communication channel bandwidth. A channel quality is estimated for a second set of candidate time-frequency resources based on the received second transmission. The communication unit is assigned one of the first and the second set of candidate time-frequency resources having a higher estimated channel quality along an additional set of time-frequency resources to the communication unit for at least data transmission by the communication unit.