KR20080036534A - Apparatus and method for synchronous spectrum sharing in wireless communication system - Google Patents

Abstract

An apparatus and a method for synchronous spectrum sharing in a wireless communication system are provided to extract idle spectrum information from a sub frame related to a sub channel exclusive for a broadcast frame in an OFDM/OFDMA wireless communication system and transmit data in an identified symbol slot not used, thereby allowing a secondary user of the system to form ad-hoc mesh network communications dynamically in a fixed or mobile scenario. In a wireless communication system having a primary user node and a secondary user node, a synchronous spectrum sharing operation of the secondary user node is performed by extracting idle spectrum information from a sub-frame related to a network sub-channel only for a broadcast frame(1015), and transmitting data within a unused symbol slot, which is identified in the extracted idle spectrum information(1025).

Description

Apparatus and method for synchronizing spectrum sharing in wireless communication system {APPARATUS AND METHOD FOR SYNCHRONOUS SPECTRUM SHARING IN WIRELESS COMMUNICATION SYSTEM}

The present invention relates to a wireless communication system, and more particularly, to an apparatus and method for synchronizing spectrum sharing in an OFDM / OFDMA wireless communication system.

Existing fixed spectrum allocation techniques result in low spectrum under-utilization. For example, experiments have shown that more than 62% of the sub-3Ghz spectrum is idle even in the busiest regions. These low usage efficiencies and increasing demands on the radio spectrum have resulted in more efficient spectrum allocation techniques and usage policies.

Currently, secondary users use only qualified spectrum within the scope that does not cause interference to the primary user. This requirement implies that the use of the spectrum changes over time and depends on the load imposed by the first user. Many existing systems use multiple channels in a wireless network. However, these systems do not form a dynamic spectrum access network. For example, existing systems assume that the set of possible channels is static. That is, the available channel is fixed at the time of network initialization. However, the set of channels available in a multi-access wireless network, such as OFDMA's Worldwide Interoperability for Microwave Access (WiMAX), changes dynamically. In addition, existing systems assume that the possible channels are homogeneous (ie, other channels have similar ranges and support similar data rates). These assumptions are incorrect, for example, when different channels are located in widely separated portions of the frequency spectrum that show different modulation schemes and different propagation characteristics. Moreover, existing systems fail to provide dedicated subchannels for private network users.

Accordingly, there is a need for a sync spectrum sharing system due to OFDM or OFDMA signal processing. In particular, there is a need for a sync spectrum sharing system for a dedicated network using OFDM or OFDMA.

An object of the present invention is to provide an apparatus and method for synchronizing spectrum sharing in an OFDM / OFDMA wireless communication system.

An object of the present invention is to extract idle spectral information from subframes associated with a dedicated network subchannel of a broadcast frame in an OFDM / OFDMA wireless communication system, and to extract data within an unused symbol slot identified in the extracted idle spectrum information. An apparatus and method for synchronizing spectrum sharing of a second user node for transmission are provided.

According to an embodiment of the present invention to achieve the above object, in a wireless communication system including a primary user node and a secondary user node, the apparatus for synchronizing spectrum sharing of a second user node may include: And a frame detector for extracting idle spectrum information from subframes associated with the dedicated network subchannels, and a node modem for transmitting data in unused symbol slots identified in the extracted idle spectrum information.

According to an embodiment of the present invention to achieve the above object, a synchronization spectrum sharing method of a second user node in a wireless communication system including a primary user node and a secondary user node may include: And extracting idle spectrum information from a subframe related to a dedicated network subchannel, and transmitting data in an unused symbol slot identified in the extracted idle spectrum information.

The present invention extracts idle spectrum information from subframes related to a dedicated network subchannel of a broadcast frame in an OFDM / OFDMA wireless communication system, and transmits data in an unused symbol slot identified in the extracted idle spectrum information. A secondary user has the advantage of being able to dynamically form ad hoc mesh network communications within a fixed or mobile scenario.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of 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, an apparatus and method for synchronizing spectrum sharing in an OFDM / OFDMA wireless communication system will be described.

1 illustrates a wireless network for synchronization spectrum sharing according to the present invention. As shown, the wireless network 100 includes three base stations (BS) 101, 102, 103. The base station 101 is in communication with a base station 102 and a base station 103, for example, with an Internet Protocol (IP) network 130 such as the Internet, a proprietary IP network, or other data network.

The base station 102 provides wireless broadband access to the IP network 130 via the base station 101 to a first plurality of subscriber stations (SSs) within its coverage area 120. to provide. The first plurality of subscriber states includes a subscriber station 111 to a subscriber station 116, for example, the subscriber station 111 is located in a small business (SB), and the subscriber station 112 is an enterprise (E). The subscriber station 113 is located in a Wi-Fi HotSpot (HS), the subscriber station 114 is located in a first house (Residence: R), and the subscriber station 115 is a second house (Residence: R). Located in, the subscriber station 116 may be a mobile device (M).

The base station 103 provides wireless broadband access to the IP network 130 through the base station 101 to the second plurality of subscriber stations 115-116 within its coverage area 125. Here, although the base station 102 and the base station 103 are described as an example of being connected to the IP network 130 indirectly through the base station 101, an optical fiber, a digital subscriber line (hereinafter referred to as 'DSL') May be directly connected to the IP network 130 through a wired broadband connection such as a cable or a T1 / E1 line.

Here, the subscriber station 115 and the subscriber station 116 are located at the boundary of the two coverage areas 120 and 125, and communicate with the base station 102 and the base station 103, respectively, and operate in the handoff mode.

The base stations 101-103 will communicate with each other, and also with the subscriber stations 111-116, an IEEE-802.16 metropolitan area network standard (e.g., an IEEE-802.16e standard) or other wireless protocol ( For example, it will communicate using the HIPERMAN wireless metropolitan area network standard. The base station 101 will communicate with the base station 102 and the base station 103 via direct line-of-sight or non-visible distance depending on the technology used for the wireless backhaul. The base station 102 and the base station 103 will communicate over non-visible distance with subscriber stations 111-116 using OFDM and / or OFDMA technology.

The base station 102 provides the T1 level service to the subscriber station 112 located in the enterprise E and the fractional T1 level service to the subscriber station 111 located in the small company SB. Will provide. In addition, the base station 102 will provide wireless backhaul to subscriber stations 113 located at Wi-Fi hotspots (HS), e.g., airports, cafes, hotels, university campuses, and DSL level services located in homes (R). Or a subscriber station 114, 115, 116, which is a mobile device (M).

The subscriber stations 111-116 use wireless broadband access to the IP network 130 to connect voice, data, video, video conferencing, and / or other broadband services. The subscriber station 116 may be one of a plurality of mobile devices including a laptop computer capable of wireless communication, a personal data assistant, a notebook, a handheld device, or other wireless communication enabled device. Will be. The subscriber station 114 and the subscriber station 115 may be, for example, a personal computer, laptop computer, gateway, or other device capable of wireless communication.

The connection from the base station 101 to servers located in an IP network 130, for example a fiber line, a central office or another operator point-of-presence, will constitute a broadband connection. . The servers will provide communication to the Internet gateway for Internet protocol based communication and also to a public switched telephone network (PSTN) gateway for voice based communication. In the case of voice-based communication in the form of voice-over-IP (VoIP), the traffic will be delivered directly to the Internet gateway instead of the PSTN gateway. Here, the connection to the IP network 130 may be provided by other network nodes and equipment.

)하고, 상기 직렬/병렬 변환기(202) 내의 매핑 함수(Mapping function : MAP)를 이용하여 각 병렬 데이터 스트림을 I와 Q 변조 심 볼에 맵핑한 후, IFFT(Inverse Fast Fourier Transform) 연산기(204)로 제공한다. 상기 IFFT 연산기(204)는 각 데이터 스트림에 IFFT 연산을 수행하고, 연산 결과를 병렬/직렬 변환 및 CP(cyclic prefix) 추가기(206)에 전달한다. 2 is a block diagram showing the configuration of a typical OFDM / OFDMA transmitter according to the present invention. The transmitter 200 first transmits the serial output of the encoded and interleaved data signal to a serial-to-parallel converter 202 to form an OFDM / OFDMA composite signal. The serial / parallel converter 202 separates each data signal into a parallel data stream (ie,

And mapping each parallel data stream to I and Q modulation symbols using a mapping function (MAP) in the serial / parallel converter 202, and then inverse fast fourier transform (IFFT) operator 204. To provide. The IFFT operator 204 performs an IFFT operation on each data stream and passes the result of the operation to a parallel / serial conversion and a cyclic prefix adder (206).

The parallel / serial conversion and CP adder 206 combines each parallel data stream into one data signal, inter-symbol interference (hereinafter referred to as 'ISI') and inter-block interference (Inter-Block). Interference: A CP is added to the combined data signal to help remove the " IBI. &Quot; The parallel / serial conversion and CP adder 206 adds multiple subcarriers to the transmission frequency and inserts a guard interval into the signal for time division duplex (TDD) mode operation. The output of the parallel / serial conversion and CP adder 206 is passed to a windowing matched filter 208 and then to an up-converter 210. The output of the up-converter 210 is transmitted to the RF stage 212 and then transmitted through the antenna 214.

)으로 분리한다. 상기 직렬/병렬 변환기(306) 내부의 MAP은 상기 분리된 각 병렬 데이터 스트림을 I 및 Q 변조심볼들에게 매핑하여 FFT 연산기(308)에 전달한다. 상기 FFT 연산기(308)는 각 데이터 스트림에 FFT 연산을 수행하고, 연산 결과를 병렬/직렬 변환 및 디코더(310)로 전달한다. 상기 병렬/직렬 변환 및 디코더(310)는 상기 데이터 스트림을 직렬 데이터 신호로 변환한 후 디코딩하여 원래 신호를 검출한다. 3 is a block diagram showing the configuration of a general OFDM / OFDMA receiver according to the present invention. The receiver 300 detects the transmitted symbols and essentially reverses the process implemented by the transmitter 200 of FIG. For example, the signal transmitted by antenna 214 is received by antenna 302. The signal is transmitted and received and transmitted to the CP canceller 304. The transmit / receive and CP canceller 304 removes the CP from the signal and forwards it to the serial / parallel converter 306. The serial / parallel converter 306 converts the data signal into a parallel data stream (ie,

Separate with). The MAP inside the serial / parallel converter 306 maps each of the separated parallel data streams to I and Q modulation symbols for delivery to the FFT operator 308. The FFT operator 308 performs an FFT operation on each data stream and transfers the result of the operation to the parallel / serial conversion and decoder 310. The parallel / serial conversion and decoder 310 converts the data stream into a serial data signal and then decodes it to detect the original signal.

)으로 분리한다. 상기 직렬/병렬 변환기(408) 내부의 MAP은 상기 분리된 각 병렬 데이터 스트림을 I 및 Q 변조심볼들에게 매핑하여 FFT 연산기(410)에 전달한다. 상기 FFT 연산기(410)는 각 데이터 스트림에 FFT 연산을 수행하고, 연산 결과를 병렬/직렬 변환 및 디코더(412)로 전달한다. 상기 병렬/직렬 변환 및 디코더(412)는 상기 데이터 스트림을 직렬 데이터 신호로 변환한 후 디코딩하여 OFDM/OFDMA 모뎀 및 검출 엔진(414)으로 출력하고, 상기 OFDM/OFDMA 모뎀 및 검출 엔진(414)은 상기 디코딩된 신호에서 원래 신호를 검출하여 상기 송수신 모듈(404)의 노드 모뎀(416)으로 출력한다.4 is a block diagram showing the configuration of a transmitter / receiver of a second user according to the present invention. The transmitter / receiver 400 of the second user includes an OFDM / OFDMA frame detector and a transceiver module. The OFDM / OFDMA frame detector 402 detects a received signal from the transmit / receive module 404. First, the received signal from the transmit / receive module 404 is delivered to the CP remover 406 of the OFDM / OFDMA frame detector 402, which removes the CP from the signal to the serial / parallel converter. Forward to 408. The serial / parallel converter 408 converts a data signal into a parallel data stream (ie,

Separate with). The MAP inside the serial / parallel converter 408 maps each of the separated parallel data streams to I and Q modulation symbols and delivers them to the FFT operator 410. The FFT operator 410 performs an FFT operation on each data stream and transfers the result of the operation to the parallel / serial conversion and decoder 412. The parallel / serial conversion and decoder 412 converts the data stream into a serial data signal, decodes it, and outputs the decoded data to an OFDM / OFDMA modem and detection engine 414. The OFDM / OFDMA modem and detection engine 414 The original signal is detected from the decoded signal and output to the node modem 416 of the transmission / reception module 404.

The OFDM / OFDMA frame detector 402 detects a broadcast OFDM waveform, synchronizes the waveform to an OFDM frame, and extracts downlink and uplink channel assignments for the frame. The OFDM / OFDMA frame detector 402 then delivers idle spectrum information to the node modem 416. The node modem 416 may be, for example, a modem including a mobile ad hoc networking (hereinafter referred to as 'MANET') node modem. To operate as an interactive node in a fixed or mobile ad hoc network, the transmit / receive module 404 may, for example, include a controller and ad hoc routing protocol module 418, a transceiver 420, a power amplifier. 422, duplexer 424, antenna 426, clock and synchronization module 428.

  Thus, the transmitter / receiver 400 identifies available or idle spectrum information and provides access to the idle spectrum to second users, for example within IEEE-802.16 or WiMAX signals. . That is, the second users are in a non-interfering or leasing basis, for example, with available channels (e.g., 'white space') in a broadcast radio waveform, such as IEEE-802.16 or WiMA. Dynamic access is possible.

5 illustrates an OFDM symbol according to an embodiment of the present invention. Here, the OFDM symbol 500 is composed of a CP 502 and a data payload 504, the total symbol period (T _s ) is the guard time (T _g ) and the useful symbol period Is greater than the sum of (T _u ). OFDM waveforms provide increased symbol duration, thereby improving the robustness of OFDM to channel delay spread. Thus, in addition to the CP 502, if the duration of the CP 502 is longer than the channel delay spread, ISI may be eliminated. The CP 502 is typically a repetition of the last sample of the data payload 504, as seen in FIG. 5 above, appended to the beginning of the data payload 504. The purpose of the CP (502) is to make the spectrum of the OFDMA signal have a 'brick wall' form, when the FFT operation is performed by transmitting '0' to the left and right subcarriers (no signal), interference to adjacent frequency bands It is to make the signal component acting as small.

Similar attributes exist for OFDMA. The OFDMA symbol structure consists of three types of subcarriers: (1) data subcarriers for data transmission, (2) pilot subcarriers for estimation and synchronization purposes, and (3) null subcarriers for no transmission. Generally used for guard bands and DC carriers). Here, dynamic subcarriers, that is, data and pilot subcarriers, are grouped into a subset of subcarriers called subchannels.

For example, in standards such as IEEE-802.16-2004 and IEEE-802.16-2005, the minimum frequency-time resource unit of subchannelization is one slot. There are two types of subcarrier permutations for the subchannelization, which are diversity permutation and contiguous permutation.

The diversity permutation selects subcarriers in a pseudo-randomly manner to form one subchannel. The diversity permutation generally provides frequency diversity and ICI averaging. The diversity permutation includes DL FUSC, DL PUSC, UL PUSC, and other optional permutations. For OFDM symbols transmitted on the DL PUSC, the available or usable subcarriers are grouped into a cluster comprising 14 contiguous subcarriers per symbol. Here, pilot and data are allocated to subcarriers grouped by cluster unit.

A re-arranging scheme is used to form a group of clusters such that each group consists of clusters distributed over subcarrier space. A subchannel in one group includes two clusters and consists of 48 data subcarriers and 8 pilot subcarriers. Similar to the cluster structure for DL PUSC, a tile structure is defined for UL PUSC. The usable subcarrier space is divided into six tiles selected across the entire spectrum by tiles and rearrangement / reordering techniques, grouped to form one slot. The slot is composed of 48 data subcarriers and 24 pilot subcarriers in three consecutive OFDM symbol intervals.

On the other hand, the adjacent permutation groups adjacent subcarriers into one block to form one subchannel. The adjacent permutation includes DL Advanced Modulation and Coding (DL AMC) and UL AMC, and has the above structure. One bin consists of nine adjacent subcarriers within one symbol. Here, eight subcarriers of the nine adjacent subcarriers are allocated for data, and one subcarrier is allocated for pilot. One slot in the AMC is defined as a collection of bins of the form (N × M = 6). Where N is the number of adjacent bins and M is the number of adjacent symbols. Thus, the allowed combinations are [(6 bins, 1 symbol), (3 bins, 2 symbols), (2 bins, 3 symbols), (1 bin, 6 symbols)]. The AMC permutation enables multi-user diversity by selecting subchannels using an optimal frequency response.

The IEEE-802.16-2005 wireless MAN OFDMA mode is based on the concept of scalable OFDMA (S-OFDMA). The S-OFDMA provides a wide range of bandwidth to adaptively handle the need for various spectrum allocation and usage model requirements. Scalability of the OFDMA system can be obtained by fixing the subcarrier frequency interval to 10.94 kHz and adjusting the FFT size. Since the resource unit subcarrier bandwidth and the symbol period are fixed, the influence on higher layers is minimized when adjusting bandwidth. Here, the S-OFDMA parameter may be represented as shown in Table 1 below.

parameter value System Channel Bandwidth (MHz) 1.25 5 10 20 Sampling Frequency (Fpp in MHz) 1.4 5.6 11.2 22.4 FFT size (NFFT) 128 512 1024 2048 Number of subchannels 2 8 16 32 Subcarrier Frequency Interval 10.94 kHz Available symbol time (Tb = 1 / f) 91.4 microseconds Guard time (Tg = Tb / 8) 11.4 microseconds OFDMA symbol period (Ts = Tb + Tg) 102.9 microseconds Number of OFDMA Symbols (5 ms Frame) 48

6A and 6B illustrate distributed subcarrier allocation according to an embodiment of the present invention. 6A and 6B show distributed subcarrier allocations 600a and 600b in the case of, for example, cell ID 0 and cell ID 1, respectively.

6A shows four subcarrier groups 602a, 602b, 602c, 602d. Each subcarrier shown in the groups 602a, 602b, 602c, 602d constitutes a particular subchannel, for example two subchannels 604a, 604b. Each of the subchannels 604a and 604b generally includes 48 data subcarriers. In a similar manner, FIG. 6B shows four subcarrier groups 606a, 606b, 606c, 606d. Each subcarrier shown in the groups 606a, 606b, 606c, and 606d constitutes a specific subchannel, for example, two subchannels 608a and 608b. Each of the subchannels 608a and 608b generally includes 48 data subcarriers.

7 illustrates a WiMAX OFDM / OFDMA broadcast frame for TDD according to an embodiment of the present invention. The broadcast frame 700 illustrates the relationship between a specified subchannel logical number 702 and a macrocell OFDM / OFDMA time slot or symbol number 704. The broadcast frame 700 is divided into a downlink subframe 706 and an uplink subframe 708, and subchannelization within the downlink subframe 706 and the uplink subframe 708. Support. The downlink subframe 706 and the uplink subframe 708 are separated by a transmit / receive transition gap (TGT) and a receive / transmit transition gap (RTG). . The transition gap 710 prevents downlink and uplink transmission collisions. The downlink subframe 706 and the uplink subframe 708 include several unused or idle spectra, such as, for example, idle blocks 712, 714, 716.

Control information for the broadcast frame 700 is used for optimal system operation. For example, the control information may include a preamble 718, a frame control head (hereinafter referred to as 'FCH') 720, a DL-MAP 722, a UL-MAP 724a and 724b, and a UL ranging. The subchannel 726 may include a UL channel quality indicator channel (hereinafter referred to as "CQICH") 728 and a UL acknowledge subchannel (hereinafter referred to as "ACK CH") 730. The preamble 718 is used for synchronization of the first symbol number 704 of the broadcast frame 700. The FCH 720 follows the preamble 718 and provides frame configuration information such as MAP message length, coding scheme, and available subchannels.

The DL-MAP 722 and the UL-MAP 724a and 724b provide subchannel allocation and control information for the downlink subframe 706 and the uplink subframe 708, respectively. The UL ranging subchannel 726 is allocated to the terminal to perform the closed-loop time, frequency, and power adjustment as well as the bandwidth request. The UL CQICH 728 is allocated to the terminal to feed back channel state information, while the UL ACK CH 730 is allocated to the terminal to feed back a DL hybrid automatic request (HARQ) acknowledgment.

The downlink subframe 706 includes a plurality of DL data bursts 732a, 732b, 732c, 732d, and 732e, and the uplink subframe 708 includes a plurality of UL data bursts 734a, 734b, 734c, 734d).

8A and 8B illustrate an OFDM / OFDMA broadcast frame including a dedicated network channel and a PU-MAP according to an embodiment of the present invention. The broadcast frame 800 includes a downlink subframe 802a and an uplink subframe 802b and many other elements similar to the broadcast frame 700 of FIG. 7. However, the broadcast frame 800 may include a dedicated network subchannel 804a in the downlink subframe 802a and a dedicated network subchannel 804b in the uplink subframe 802b. Include.

The dedicated network subchannels 804a and 804b may occupy all or a plurality of subchannels in the broadcast frame 800, and may occupy a portion of one subchannel or several portions of a plurality of channels. The dedicated network subchannels 804a and 804b may be, for example, a personal network, an enterprise network, a premium service network, a specific femtocell device or a group of femtocell devices, a specific WiMAX cell or a group of WiMAX cells. May be used by a small office / home office (SOHO) or group of SOHOs, a femtocell or group of femtocells, or other device groups requiring dedicated services for any other network, subnetwork or other specific user or group of users. Is reserved.

One separate subchannel (eg, dedicated network subchannels 804a, 804b) for private use of private network users minimizes interference of cellular services because the OFDMA subcarriers are orthogonal.

Each dedicated network subchannel 804a, 804b is associated with a private user subframe or a private user map (hereinafter referred to as a 'PU-MAP') 806. The PU-MAP 806 provides subchannel allocation and control information for at least one of the dedicated network subchannel 804a and the dedicated network subchannel 804b. In other words, the PU-MAP 806 identifies subcarriers (eg, idle spectrum) available to members of a particular dedicated network. For example, the PU-MAP 806 provides information on subcarriers available within the broadcast frame 800, more specifically, idle spectrum information associated with the dedicated network subchannels 804a and 804b. In this case, the PU-MAP 806 may be expressed in a format as shown in Table 2 below.

Syntax Size Notes PU_MAP () {  N_SLOTS 8 bits The number of idle slots available in the frame.   For (n = 0; n <N_SLOTS; n ++) {    PERM_Indicator 1 bit Indicates whether or not open slot ‘n’, as defined by the parameters below, is available in all future frames.    UL-DL Indicator 1 bit Indicates whether open slot ‘n’ is in the Up Link frame (‘0’) or the Down Link frame (‘1’).    OFDMA Symbol Offset 8 bit The offset of the OFDMA symbol in which slot n starts, measured in OFDMA symbols from the beginning of frame in which open slot ‘n’ is included (either UL or DL, depending on the UL-DL Indicator).    Subchannel Offset 6 bit The lowest index OFDMA subchannel in open slot n, starting from subchannel ‘0’    No. OFDMA Symbols 7 bit The number of OFDMA symbols that make up open slot ‘n’.    No. Channels 6 bit The number of subchannels, with subsequent indexes, that make up slot ‘n’

The location of the PU-MAP 806 in the broadcast frame 800 may vary. For example, the PU-MAP 806 may be part of a reserved spectrum, such as dedicated network subchannel 804a, as shown in FIG. 8A, or as shown in FIG. 8B. It may be separated from the network subchannel 804b and adjacent to the UL-MAP 624b. Further, the PU-MAP 806 may be located in an appropriate portion of the broadcast frame 800 that is easily accessible by secondary users or second nodes, and within a particular broadcast frame 800. It may occupy an appropriate number of subchannels and / or symbol intervals. In addition, the PU-MAP 806 may be located adjacent to the DL-MAP 622. Members of a particular dedicated network and other particular second nodes may know the location of the PU-MAP 806. For example, a bit setting in the FCH 620 or DL-MAP 622 may be used to indicate the presence of the PU-MAP 806. Of course, other suitable methods for indicating the presence of the PU-MAP 806 may be used.

For example, the PU-MAP 806 identifies carriers grouped into one or more dedicated network subchannels 804a, 804b. The format of the dedicated network subchannels 804a, 804b identifies dedicated network pilot subcarriers used for channel estimation by the second nodes. The PU-MAP 806 extracts idle spectrum information associated with at least one of the dedicated network subchannels 804a and 804b and provides the information to second nodes associated with the dedicated network.

Thus, the PU-MAP 806 includes information accessible by the members of the dedicated network to assist in sending and receiving data. For example, when a femtocell device associated with a WiMAX network is assigned to a DL burst slot, the WiMAX Base Transceiver Station (BTS) sends the PU-MAP 806 to the femtocell. Nodes associated with the dedicated network must know the CID of the femtocell device so that the node can determine when to listen for transmission of information related to the PU-MAP 806. The nodes provide their own local CIDs used by the PU-MAP 806 to identify DL and UL burst slots or idle spectrum in dedicated network subchannels 804a, 804b. Thus, the dedicated network nodes can transmit / receive bursts in the identified slots.

8C illustrates an OFDM / OFDMA broadcast frame including a second node data burst in an unused OFDM symbol slot in a dedicated network subchannel according to an embodiment of the present invention. Here, referring to the positions of the idle spectrum blocks in the downlink subframe 802a, that is, the second node data bursts, the second node data bursts 808a, 808b, and 808c are symbols that are not used in the broadcast frame 800. Is located at number 704. For example, the second node data burst 808a occupies the fifth symbol number in the dedicated network subchannel 804a, and the second node data burst 808b is the ninth to tenth in the dedicated network subchannel 804a. Occupies a symbol number, and the second node data burst 808c also occupies an unused symbol number in the dedicated network subchannel 804a.

8D is an exemplary diagram illustrating a cluster of second nodes in a wireless network according to an embodiment of the present invention. 8D is another illustration of FIG. 8C with idle spectral blocks 808a, 808b, 808c, wherein each of the second nodes 810a-810k may have a set of subcarrier local number 702 and symbol number 704 set. It may be determined whether to be idle or not allocated for a given OFDM / OFDMA frame. For example, the second node 810 can place the idle spectrum block 808 within the dedicated network subchannel 804a during a given OFDM / OFDMA frame, such as within the broadcast frame 800. In addition, the second node 810 may position the idle spectrum in subchannels found within the broadcast frame 800, such as in the idle block 712 or idle block 714, for example. .

If one of the second nodes 810a-810k does not have data to transmit, then the second node may apply idle subcarriers during idle symbol periods (eg, idle spectral blocks 808a, 808b, 808c). Listens for data symbols transmitted by a neighboring second node on the other hand, if one of the second nodes 810a-810k has data to transmit, then the second node transmits on an idle subcarrier during an idle symbol period. The transmission data is transmitted to neighboring second nodes.

Thus, the present invention provides one system for providing shared spectrum to ad hoc network users in networks that use non-interfering or leasing basis OFDMA. The dedicated network subchannels 804a, 804b should be reserved primarily for dedicated or private networks and not assigned to users who are not part of an ad hoc or dedicated network. The RF transmitter power of the devices in the dedicated network should help limit the size of the dedicated network coverage area.

Here, the BTS can notify the users of the dedicated network of subcarriers reserved for the dedicated network in a particular cell. For example, the MAC processing block of a particular BTS may convey information about dedicated network subchannels 804a and 804b to the second nodes 810a-810k. In order to establish access to the OFDMA channel, the second nodes 810a-810k detect broadcast OFDMA waveforms and synchronize to OFDMA frames to extract idle spectrum information using a frame detector.

9, the symbol period or length Tx of the second node data bursts 808a, 808b, 808c is equal to the OFDM symbol period Ts in the broadcast frame 800. The interval is maintained to be smaller than or equal to the OFDM symbol interval Ts. The second node data bursts 808a, 808b, 808c may use a variable length symbol format. However, the shorter symbol interval Tx includes a larger subcarrier spacing if the second node modulation is in accordance with OFDM.

Here, the second nodes 810a-810k start transmission after the guard time Tg as in the ALOHA technique shown in FIG. 9. The transmitting node determines whether other second nodes 810a-810k are already transmitting within an unassigned subcarrier in symbol number 704 by existing carrier sense multiple access (CSMA) techniques. For example, the second node 810c may transmit data in the idle spectrum block 808a and at the same time the second node 810b may transmit data in the idle spectrum block 808b. Moreover, two second nodes can transmit simultaneously in the same symbol number 704 in different subcarriers. If unassigned subcarriers are found to be used by other second nodes, then the other second nodes wait for the next idle block (eg, idle spectrum blocks 808a, 808b, 808c) or idle blocks 712, 714. 716), the access process is repeated.

On the other hand, the battery life of the second node using the battery can be extended. For example, the second node can power off a transmitter circuit that has no data to transmit. In addition, the second node may power off receiver circuitry and other non-essential circuits during symbol number 704 where no idle subcarriers are present. For example, the second node may power on at a suitable time to receive the broadcast frame 800, the DL-MAP 722, the UL-MAP 724a, 724b, and the PU-MAP 806.

10 is a flowchart illustrating a synchronization spectrum sharing method according to an embodiment of the present invention. In this case, the dedicated network subchannel is 804a of FIGS. 8A to 8C, for example. Referring to FIG. 10, in order to access the OFDMA channel, the OFDM / OFDMA frame detector of the second node detects a broadcast OFDMA waveform in step 1005, and detects the same in an OFDMA frame such as the broadcast frame 800 in step 1010. Synchronize the waveform.

Thereafter, the frame detector extracts downlink and uplink channel assignments for the corresponding frame in step 1015, and idles them from individual user subframes or maps (eg, PU-MAP 806) associated with the dedicated network channel 804a. Extract spectral information. Thereafter, the frame detector transmits the extracted idle spectrum information to the node modem included in the second node in step 1020.

The second node obtains dynamic access to the dedicated network channel 804a using the idle spectrum block 808 (ie, 'white space'), and in step 1025 non-interfering or leasing basis ( Data may be transmitted in an idle spectrum block 808 within a leasing basis. Thus, secondary node users are dynamically added within fixed or mobile scenarios without interfering with consents / etiquette granted by primary users and / or other users, such as ordinary entities. Or may form mesh network communications.

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.

1 illustrates a wireless network for synchronization spectrum sharing in accordance with the present invention;

2 is a block diagram showing the configuration of a general OFDM / OFDMA transmitter according to the present invention;

3 is a block diagram showing the configuration of a typical OFDM / OFDMA receiver according to the present invention;

4 is a block diagram showing the configuration of a transmitter / receiver of a second user according to the present invention;

5 illustrates an OFDM symbol according to an embodiment of the present invention;

6A and 6B illustrate distributed subcarrier allocation according to an embodiment of the present invention;

7 illustrates a WiMAX OFDM / OFDMA broadcast frame for TDD according to an embodiment of the present invention.

8A and 8B illustrate an OFDM / OFDMA broadcast frame including a dedicated network channel and a PU-MAP according to an embodiment of the present invention;

8C illustrates an OFDM / OFDMA broadcast frame including a second node data burst in an unused OFDM symbol slot in a dedicated network subchannel according to an embodiment of the present invention;

8D is a diagram illustrating a cluster of second nodes in a wireless network according to an embodiment of the present invention;

9 illustrates a second node data burst associated with an OFDMA frame structure for a given OFDM symbol interval in accordance with an embodiment of the present invention; and

10 is a flowchart illustrating a procedure of a synchronization spectrum sharing method according to an embodiment of the present invention.

Claims (18)

An apparatus for synchronizing spectrum sharing of a second user node in a wireless communication system including a first user node and a second user node, A frame detector for extracting idle spectrum information from subframes related to a dedicated network subchannel of a broadcast frame; And a node modem for transmitting data in an unused symbol slot identified in the extracted idle spectrum information. The method of claim 1, And the subframe includes a portion of the dedicated network subchannel. The method of claim 1, And the subframe is related to at least one of a downlink subframe of the broadcast frame and an uplink subframe of the broadcast frame. The method of claim 1, The users of the dedicated network subchannel include a private network of second users. The method of claim 1, And the dedicated network subchannel comprises at least one of all subchannels of the frame, some subchannels of the frame, and two or more subchannels of the frame. The method of claim 1, And the frame detector detects the broadcast frame of a broadcast waveform. The method of claim 1, And the broadcast frame is one of an OFDM frame and an OFDMA frame. The method of claim 1, And the idle spectrum information includes a downlink channel assignment and an uplink channel assignment associated with the dedicated network subchannel. The method of claim 1, And said node modem and frame detector are synchronized. The method of claim 9, And said node modem is a MANET node modem. A method of sharing spectrum of a second user node in a wireless communication system including a primary user node and a secondary user node, the method comprising: Extracting idle spectrum information from a subframe related to a dedicated network subchannel of a broadcast frame; Transmitting data in an unused symbol slot identified in the extracted idle spectrum information. The method of claim 11, The subframe includes a portion of the dedicated network subchannel. The method of claim 11, The subframe may be related to at least one of a downlink subframe of the broadcast frame and an uplink subframe of the broadcast frame. The method of claim 11, Users of the dedicated network subchannel include a private network of second users. The method of claim 11, Wherein the dedicated network subchannel comprises at least one of all subchannels of the frame, some subchannels of the frame, and two or more subchannels of the frame. The method of claim 11, wherein Detecting the broadcast frame of a broadcast waveform. The method of claim 11, The broadcast frame is characterized in that one of the OFDM frame and OFDMA frame. The method of claim 11, The idle spectrum information includes a downlink channel assignment and an uplink channel assignment associated with the dedicated network subchannel.

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