KR20080054131A - Apparatus and method for resource allocation in broadband wireless communication system - Google Patents

Abstract

An apparatus and a method for allocating resources in a broadband wireless communication system are provided to select a resource allocation tree node according to the channel characteristics of each terminal and allocate resources to an uplink pilot by combining resource allocation tree nodes, thereby preventing the pilot collision of the each terminal and transmitting the resources to the uplink pilot with a small amount of information. A scheduler(201) comprises a channel characteristic checking unit(301), a pilot requirement setting unit(303), and a pilot resource allocating unit(305). The channel characteristic checking unit checks the channel characteristics of each terminal using the pilot of the each terminal received from a feedback receiver. The pilot requirement setting unit sets the pilot requirement conditions of the each terminal according to the channel characteristics of the each terminal received from the channel characteristic checking unit. The pilot resource allocating unit allocates resources to the uplink pilot of the each terminal using the pilot requirement condition information of the each terminal received from the pilot requirement setting unit.

Description

Resource allocation apparatus and method in broadband wireless communication system {APPARATUS AND METHOD FOR RESOURCE ALLOCATION IN BROADBAND WIRELESS COMMUNICATION SYSTEM}

1 is a diagram illustrating a resource structure allocated for an uplink pilot in a broadband wireless communication system according to the prior art;

2 is a block diagram of a base station in a broadband wireless communication system according to the present invention;

3 is a block diagram illustrating a detailed block configuration of a scheduler in the broadband wireless communication system according to the present invention;

4 is a diagram illustrating an operation procedure of a base station in a broadband wireless communication system according to an embodiment of the present invention; and

5 is a diagram illustrating a resource structure allocated for an uplink pilot in a broadband wireless communication system according to an embodiment of the present invention.

The present invention relates to an apparatus and method for allocating resources of a broadband wireless communication system, and more particularly, to an apparatus and method for allocating resources for an uplink pilot signal of each terminal in the broadband wireless communication system.

The broadband wireless communication system performs resource allocation based on uplink / downlink channel information. In this case, the channel information of the uplink / downlink is estimated using the pilot included in the uplink / downlink signal. For example, in the case of downlink, the base station of the broadband wireless communication system transmits a pilot signal over the entire frequency band. Accordingly, the terminal may estimate the downlink channel by receiving the pilot signal.

In the case of uplink, when the terminals transmit pilot signals at the same time and frequency position, the pilot signals collide. Accordingly, the base station should allocate different time and frequency positions for the mobile station to transmit a pilot signal. Here, the Institute of Electrical and Electronics Engineers (IEEE) 802.20 D1 draft standard has a resource allocation structure for an uplink pilot as shown in FIG. 1.

1 illustrates a resource structure allocated for an uplink pilot of a broadband wireless communication system according to the prior art.

Referring to FIG. 1, according to the IEEE 802.20 D1 standard, the uplink pilot includes a reverse dedicated pilot channel (R-DPICH) as shown in FIG. It transmits on a reverse pilot channel (R-PICH (Reverse link-Pilot Channel)) as shown in FIG.

First, when using the reverse dedicated pilot channel, as shown in FIG. 1 (a), the terminal transmits the pilot together with uplink data. That is, the terminal transmits the pilot together with the uplink data so that the base station can measure a channel state of a frequency band currently used among all frequency bands of the terminal. Therefore, the base station uses the channel information estimated through the pilot as a reference for detecting received data.

Next, when using the reverse pilot channel, as shown in (b) of FIG. 1, the terminal transmits the pilot through a resource of a frequency band determined according to time resources. That is, the terminal transmits the pilot through the resource of the frequency band determined according to the time resource so that the base station can measure the channel state of the entire frequency band of the terminal. Accordingly, the base station allocates resources of the terminal using channel information estimated through the pilot. Here, the terminal transmits the pilot in units of a reverse link-phy frame of a reverse link.

As described above, the terminal of the broadband wireless communication system transmits an uplink pilot using the reverse dedicated pilot channel and the reverse pilot channel. In this case, the base station performs reception data detection or resource allocation using the uplink pilot. In this case, the wideband wireless communication system has a limited frequency range and resolution for measuring the uplink channel. In addition, the uplink channel measurement period through the pilot in the broadband wireless communication system is also limited by the data transmission time and hopping time.

In another embodiment, in case of IEEE 802.16e, the terminal transmits an uplink pilot together with the uplink data or transmits the uplink pilot using a sounding channel.

First, when transmitting the pilot with the uplink data, the terminal transmits the pilot with the uplink data so that the base station can measure the channel state of the frequency band currently used by the terminal. Therefore, the base station uses the channel information estimated through the pilot as a reference for detecting received data.

Next, when using the sounding channel, the broadband wireless communication system allocates a specific time resource and a frequency resource as a sounding channel for uplink pilot. Accordingly, the terminal transmits the uplink pilot using the sounding channel. In this case, the base station allocates resources of the terminal using channel information estimated through pilot received through the sounding channel.

When the sounding channel is used in the wideband wireless communication system, the base station should allocate resources for the sounding channel of each terminal to transmit to each terminal. At this time, the resource for transmitting the allocation information of the resource for the sounding channel has a problem that acts as a large overhead of the broadband wireless communication system.

As described above, the base station of the broadband wireless communication system should be able to measure the uplink channel of each terminal for each desired frequency range, resolution, and desired time period in order to perform the uplink scheduling. In order for the base station to transmit an uplink channel of the terminal to a desired frequency range, resolution, and a desired time period to each terminal, too much resource is consumed, resulting in an increase in overhead of the system. In addition, when limiting the uplink pilot to reduce the overhead of the broadband wireless communication system, there is a problem that the frequency range and resolution for measuring the uplink channel is limited.

Accordingly, an object of the present invention is to provide an apparatus and method for allocating resources for an uplink pilot of each terminal in a broadband wireless communication system.

Another object of the present invention is to provide an apparatus and method for allocating resources for an uplink pilot of each terminal so that an uplink pilot of each terminal does not overlap each other in a broadband wireless communication system.

Another object of the present invention is to allocate resources for the uplink pilot of each terminal so that the base station of the broadband wireless communication system can measure the uplink channel of each terminal at a desired frequency range, resolution and desired time period. To provide an apparatus and method for.

According to a first aspect of the present invention for achieving the above object, a method for allocating resources for the uplink pilot at the transmitting end of the broadband wireless communication system, the process of identifying the channel characteristics for the receiving end, the channel characteristics And setting the pilot allocation conditions of the receivers, and allocating resources for the pilots of the receivers by combining the pilot allocation conditions.

According to a second aspect of the present invention, a transmitting end device for allocating resources for an uplink pilot in a broadband wireless communication system includes a channel characteristic checking unit for checking channel characteristics of receiving terminals, and a pilot of the receiving terminals according to the channel characteristics. And a resource allocation unit for allocating resources for the pilots of the receivers by combining the pilot allocation conditions.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In describing the present invention, when it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, the present invention describes a technique for allocating resources for uplink pilot of each terminal in a broadband wireless communication system. In other words, a technique for allocating resources for an uplink pilot of each terminal so that a base station of the broadband wireless communication system can measure an uplink channel of each terminal at a desired frequency range, resolution, and desired period of time. Explain about.

Hereinafter, a description will be given of an example of a broadband wireless communication system using an orthogonal frequency division multiple access method.

2 is a block diagram of a base station in a broadband wireless communication system according to the present invention.

As shown in FIG. 2, the base station includes a scheduler 201, an encoder 203, a modulator 205, an OFDM modulator 207, an RF processor 209, and a feedback receiver 211.

First, the scheduler 201 allocates resources for uplink pilot of each terminal according to channel characteristics of each terminal. In this case, the scheduler 201 transmits resource allocation information for the uplink pilot of the respective terminals to the terminals. For example, the scheduler 201 is configured as shown in FIG. 3 below.

3 illustrates a detailed block configuration of a scheduler in the broadband wireless communication system according to the present invention.

As shown in FIG. 3, the scheduler 201 includes a channel characteristic checking unit 301, a pilot request condition setting unit 303, and a pilot resource allocating unit 305.

First, the channel characteristic checking unit 301 checks the channel characteristics of each terminal by using the pilots of the respective terminals provided from the feedback receiver 211. Here, the channel characteristics include frequency range, delay spread, and Doppler frequency.

The pilot requirement setting unit 303 sets pilot requirement of each terminal according to channel characteristics of each terminal provided from the channel characteristic checking unit 301. For example, the base station should be able to measure the uplink channel of the terminals in a desired frequency range, resolution, and time period for uplink scheduling. Accordingly, the pilot requirement setting unit 303 sets the pilot frequency range according to the supportable frequency range or the preferred frequency band information of the terminal and sets the frequency resolution of the pilot according to the delay spread information. do. In addition, the pilot request condition setting unit 303 sets a time period of the pilot according to the Doppler frequency information. In this case, the pilot requirement setting unit 303 sets a pilot requirement according to each channel characteristic by using a resource allocation tree according to channel characteristics of the terminals.

The pilot resource allocator 305 is an uplink pilot of each terminal using pilot requirement information (eg, pilot frequency range, resolution, and time period) of each terminal provided from the pilot requirement setting unit 303. Allocate resources for In this case, the pilot resource allocation unit 305 so that the pilot requirements of the respective terminals do not match so as not to cause a collision in the pilots of the respective terminals.

The feedback receiver 211 receives a pilot signal from each terminal and provides it to the scheduler 201.

The encoder 203 encodes data to be transmitted according to a predetermined code rate according to scheduling information of each terminal provided from the scheduler 201.

The modulator 205 modulates and outputs a signal provided from the encoder 203 according to a corresponding modulation scheme.

The OFDM modulator 207 outputs a time domain signal by performing inverse fast Fourier transform on the frequency domain signal provided from the modulator 205.

The RF processor 209 frequency-modulates the baseband signal provided from the OFDM modulator 207 into a high frequency signal (RF signal) and outputs it through an antenna.

4 is a flowchart illustrating an operation procedure of a base station in a broadband wireless communication system according to an exemplary embodiment of the present invention.

Referring to FIG. 4, first, the base station determines whether pilot signals are received from the respective terminals in step 401.

If the pilot signals are received from the terminals, the base station proceeds to step 403 to check the channel characteristics for each terminal using the received pilot signals. Here, the channel characteristics include frequency range, delay spread, and Doppler frequency.

After checking the channel characteristics for each terminal, the base station proceeds to step 405 to set pilot requirements for each terminal according to the channel characteristics. That is, the base station sets a pilot requirement according to each channel characteristic by using a resource allocation tree according to channel characteristics of the terminals. For example, the resource allocation tree is configured as shown in FIG.

5 illustrates a resource structure allocated for an uplink pilot in a broadband wireless communication system according to an embodiment of the present invention.

As shown in (a) of FIG. 5, the base station includes a resource allocation tree according to channel characteristics of the terminals.

First, tree A 500 represents a tree for allocating pilot frequency range information according to a supportable bandwidth or a preferred band of the terminal. In this case, when the broadband wireless communication system has 16 subcarriers, the tree A 500 has pilot allocation information as shown in Table 1 below.

index Resource allocation information One 1111111111111111 01 0000000011111111 10 1111111100000000 0001 0000000000001111 0010 0000111100000000 0100 0000000011110000 1000 1111000000000000

Here, in the resource allocation information, 0 represents a portion where the pilot is not located, and 1 represents a portion where the pilot is located.

Next, the tree B 510 represents a tree for allocating pilot resolution information according to the delay spread of the channel. In this case, when the broadband wireless communication system has 16 subcarriers, the tree B 510 has pilot allocation information as shown in Table 2 below.

index Resource allocation information One 1111111111111111 01 0101010101010101 10 1010101010101010 0001 0001000100010001 0010 0100010001000100 0100 0010001000100010 1000 1000100010001000

Here, in the resource allocation information, 0 represents a portion where the pilot is not located, and 1 represents a portion where the pilot is located.

Next, tree C 520 represents a tree for allocating a pilot time period according to the Doppler frequency. In this case, when the broadband wireless communication system uses 16 time slots, the tree C 520 has pilot allocation information as shown in Table 3 below.

index Resource allocation information One 1111111111111111 01 0101010101010101 10 1010101010101010 0001 0001000100010001 0010 0100010001000100 0100 0010001000100010 1000 1000100010001000

Here, in the resource allocation information, 0 represents a portion where the pilot is not located, and 1 represents a portion where the pilot is located.

After setting the pilot requirement according to the channel characteristic, the base station proceeds to step 407 and allocates resources for pilot of each terminal according to the set pilot requirement. For example, when the broadband wireless communication system uses 16 subcarriers and 16 time slots, when UE 1 sets pilot requirements as shown in Table 4 below, Equation 1 is used. Allocates resources for the pilot of the terminal 1.

Tree types Resource allocation information Tree A 10-> 1111111100000000 Tree B 01-> 0101010101010101 Tree C 0100-> 0100010001000100

Here, in the resource allocation information, 0 represents a portion where the pilot is not located, and 1 represents a portion where the pilot is located. In this case, the resource allocation information of the tree A and the tree B represents resource allocation information for subcarriers, and the tree B represents resource allocation information for time resources.

A pilot request condition for UE 1 as shown in Table 4 is applied to Equation 1 below to allocate resources for pilot of UE 1.

B는 각 요소들(Element)의 곱([a₁×b₁, a₂×b₂, …, a_n×b_n])을 나타내 고, 상기 ×는 상기 (A.×B) 행렬과 C행렬의 곱을 나타낸다.Here, R denotes resource allocation information for the pilot of the terminal 1, and A, B, and C indicate pilot requirement conditions of the tree A, tree B, and tree C. At this time, the A

B denotes the product of each Element ([a ₁ × b ₁ , a ₂ × b ₂ ,..., A _n × b _n ]), where × is the (A. × B) matrix and C Represents the product of a matrix.

Resource allocation information for the pilot of the terminal 1 determined according to Equation 1 is shown in Table 5 below.

Resource allocation information R 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Here, in the resource allocation information, 0 indicates a portion where the pilot is not located, and 1 indicates a portion where the pilot of the terminal 1 is located. In this case, the vertical axis of the resource allocation information represents a frequency resource, the horizontal axis represents a time resource.

After allocating resources for the pilots of the respective terminals, the base station proceeds to step 409 and transmits resource allocation information for the pilots to each terminal. The base station then terminates this algorithm.

As described above, the base station sets pilot requirements according to channel characteristics of the respective terminals. Thereafter, the base station determines the pilot position of each terminal by combining the pilot requirements. For example, the base station allocates one node in each tree of the tree A, tree B, and tree C according to the pilot's frequency range, frequency resolution, and time period. Thereafter, the base station determines the pilot position of each terminal by combining the nodes allocated to each terminal.

In this case, the base station should allocate resources for each terminal so that collision does not occur in the pilot of each terminal. That is, the base station should determine the position of the pilot of each terminal so that the position of the pilot of each terminal does not overlap. Accordingly, the base station allocates the nodes of the tree to each terminal so that all three nodes allocated to the terminals do not overlap. That is, two or less nodes among the three nodes allocated by the base station to the respective terminals may overlap.

For example, when the broadband wireless communication system uses 16 subcarriers and 16 time slots, pilot requirements according to channel characteristics of each terminal are shown in Table 6 below.

Terminal Tree types Resource allocation information  Terminal 1 Tree A 10-> 1111111100000000 Tree B 01-> 0101010101010101 Tree C 01-> 0101010101010101  Terminal 2 Tree A 10-> 1111111100000000 Tree B 01-> 0101010101010101 Tree C 10-> 1010101010101010  Terminal 3 Tree A 01-> 0000000011111111 Tree B 01-> 0101010101010101 Tree C 10-> 1010101010101010

In the resource allocation information, 0 indicates a portion where the pilot is not located, and 1 indicates a portion where the pilot is located.

As shown in Table 6, a pilot request condition is applied to Equation 2 to allocate resources for pilots of the terminal 1, the terminal 2, and the terminal 3.

B는 각 요소들(Element)의 곱([a₁×b₁, a₂×b₂, …, a_n×b_n])을 나타낸다.Here, R denotes resource allocation information for pilots of UE 1, UE 2, and UE 3, and A _i , B _i , and C _i indicate pilot requests of the tree A, tree B, and tree C of the i-th terminal. Indicates a condition. At this time, the A

B represents a product ([a ₁ × b ₁ , a ₂ × b ₂ ,..., A _n × b _n ]) of each element.

Resources for the pilot of the terminal 1, the terminal 2 and the terminal 3 using the equation (2) is allocated, as shown in (b) of FIG.

The above-described embodiment has been described with an example of acquiring each channel characteristic by using the pilot of the terminal in the base station in the broadband wireless communication system. In another embodiment, the terminal may check each channel characteristic and transmit the channel characteristic to the base station.

Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications are possible without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined not only by the scope of the following claims, but also by the equivalents of the claims.

As described above, in the broadband wireless communication system, by selecting a resource allocation tree node according to channel characteristics of each terminal and allocating resources for an uplink pilot by combining the resource allocation tree nodes, pilot collision of each terminal can be prevented. It is possible to transmit the resource for the uplink pilot with a small amount of information.

Claims (16)

A method for allocating resources for an uplink pilot at a transmitting end of a broadband wireless communication system, Checking the channel characteristics of the receiving end; Setting pilot allocation conditions of the receiving terminals according to the channel characteristic; And allocating resources for the pilots of the receivers by combining the pilot allocation conditions. The method of claim 1, The channel characteristic may include at least one of a supportable frequency range or a preferred frequency band of the receivers, delay spread of a channel, and a Doppler frequency. The method of claim 1, Checking the channel characteristics, Checking whether pilots are received from the receivers; And when the pilot is received, checking channel characteristics of the receivers using the pilot. The method of claim 1, Checking the channel characteristics, Checking whether a feedback signal is received from the receivers; And when the feedback signal is received, checking channel characteristics of the receivers included in the feedback signal. The method of claim 1, The requirements for the pilot assignment include at least one of a frequency range of the pilot, a frequency resolution of the pilot, and a time period of the pilot. The method of claim 1, Setting the requirements for the pilot allocation, Checking the resource allocation structure set for each channel characteristic; And selecting the pilot allocation condition for each channel characteristic of the receiving end in the resource allocation structure. The method of claim 6, The resource allocation structure is a resource allocation tree for each channel characteristic. The method of claim 1, Allocating a resource for the pilot, Checking and comparing the pilot allocation conditions for each channel characteristic of the receivers; And when the pilot allocation conditions of the first and second receivers do not match, allocating the resources for the pilots of the receivers by combining the pilot allocation conditions. The method of claim 1, Transmitting resource allocation information for the pilots of the receivers to the receivers. A transmitting end device for allocating resources for an uplink pilot in a broadband wireless communication system, A channel characteristic verification unit for verifying channel characteristics of the receiver; A pilot assignment condition setting unit for setting pilot assignment conditions of the receivers according to the channel characteristic; And a resource allocator for allocating the resources for the pilots of the receivers by combining the pilot allocation conditions. The method of claim 10, The channel characteristic checking unit, And identifying a channel characteristic of at least one of a supportable frequency range or a preferred frequency band, a delay spread of a channel, and a Doppler frequency using the pilots received from the receivers. The method of claim 10, The channel characteristic checking unit, And identifying a channel characteristic of at least one of a supportable frequency range or a preferred frequency band, a delay spread of a channel, and a Doppler frequency in the feedback signals received from the receivers. The method of claim 10, The pilot assignment condition setting unit, And setting a pilot allocation condition for each channel characteristic of the receiving end in a resource allocation tree set for each channel characteristic. The method of claim 13, The pilot assignment condition setting unit selects at least one pilot assignment condition among a frequency range of the pilot, a frequency resolution of the pilot, and a time period of the pilot according to channel characteristics of the receivers in the resource allocation tree. Device. The method of claim 10, The resource allocation unit, When the pilot allocation conditions of the first and second receiving end do not match by checking and comparing the pilot allocation conditions of the receiving end, the pilot allocation conditions are combined to allocate resources for the pilot of the receiving end. Device. The method of claim 10, And a transmitter for transmitting resource allocation information for the pilots of the receivers to the receivers.

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