RU2541929C2 - Method and device of data transmission and reception in signal frame - Google Patents

Abstract

FIELD: physics, computer engineering.

SUBSTANCE: invention relates to data transmission via signal frames, which include multiple preambles of synchronisation. The method and system for transmission of usage in a signal frame include insertion of the first preamble of synchronisation into the first location in the signal frame and insertion of the second preamble of synchronisation into the second location in the signal frame, in which the first preamble of synchronisation transmits information that indicates the second location. The method additionally includes transmission of the signal frame to the receiving device in a wireless communication medium.

EFFECT: improved efficiency of usage of a channel pass band and provision of quick synchronisation.

31 cl, 18 dwg

Description

CROSS LINK TO RELATED APPLICATIONS

[001] This application under the provisions of document 35 USC § 119 (e) is filed in favor of provisional patent application US number 61 / 222,976, filed July 3, 2009. The content of the aforementioned patent application is incorporated herein by reference.

[002] This application is in part a continuation of the US patent application (TBD number) resulting from the conversion of 37 CFR § 1.53 (c) (3) of US provisional patent application No. 61 / 222,976, filed July 3, 2009, and which it is filed in favor of provisional patent application US serial number 61 / 078,544, filed July 7, 2008. The contents of the aforementioned patent applications are incorporated herein by reference.

FIELD OF THE INVENTION

[003] The present invention relates generally to the field of data transmission via a wireless connection, and more particularly to data transmission through signal frames that include multiple synchronization preambles.

BACKGROUND OF THE INVENTION

[004] The demand for services in which data is transmitted over a wireless connection is constantly growing and is expected to continue to grow. This includes applications in which data is transmitted via mobile cellular telephony or other mobile telephony, personal communication systems (PCS) and digital or high-definition television (HDTV). Although demand for these services is growing, the bandwidth of the channel through which data can be delivered is limited. Therefore, high speed data delivery with limited bandwidth is required in an efficient and cost-effective manner.

[005] A known method for efficiently transmitting high-speed data on a channel using orthogonal frequency channel multiplexing (OFDM). High-speed data signals are divided into tens or hundreds of lower-speed signals that are transmitted in parallel at the corresponding frequencies within the main radio frequency (RF) of the signal, which are known as sub-carriers ("sub-carriers"). The subcarrier frequency spectra are superimposed so that the spacing between them is minimal. The subcarriers are also orthogonal to each other so that they are statistically independent and do not cause crosstalk or interfere with each other otherwise. As a result, the channel bandwidth is used much more efficiently than in conventional single-carrier transmission schemes, for example, in amplitude or frequency modulation (AM / FM).

[006] Another approach to making channel bandwidth more efficient is to transmit data using a base station having multiple antennas, and then receiving the transmitted data using a remote station having multiple receiving antennas with multiple input - multiple output (MIMO). Data can be transmitted with spatial diversity between the signals studied by the respective antennas, thereby increasing the information capacity by increasing the number of antennas. Alternatively, data is transmitted with time diversification between the signals transmitted by the respective antennas, thereby reducing the likelihood of signal loss.

[007] In OFDM and MIMO systems, the preamble can be inserted into the signal frame to provide the following processes: base station identification and station selection, CIR measurement, frame and time synchronization, frequency synchronization, as well as channel estimation. In many cases, the search for a preamble requires a large amount of computation at the subscriber station. To search for the initial cell, there is no prior knowledge of synchronization positions for potential base station candidates; therefore, the subscriber station must correlate with all possible pseudo noise (PN) sequences for each position of the fast Fourier transform window within the entire search window. Such a window could be even larger for a synchronous network of base stations. To transfer control, even if there is information about the list of adjacent base stations received from the attached base station, the search for the preamble has an excessively high computational complexity.

[008] Advances in communication systems, such as standards in the evolution of WiMAX, have led to concepts that rely on the initial frame structure found in the original 802.16e standard. These concepts lead to new possibilities for addressing and synchronization in communication systems. These concepts and capabilities can also be applied to any 3GPP or 3GPP2 system.

[009] Therefore, it is required to find preambles that provide easy and fast synchronization between the subscriber station and base stations and which reduce the complexity of quick cell search after rough synchronization.

[010] Accordingly, there is a need for an improved preamble structure, method and apparatus that are suitable for mobile wireless broadband access systems.

SUMMARY OF THE INVENTION

[011] In accordance with a first general objective, the present invention provides a method for transmitting data in a signal frame. The method includes inserting a first synchronization preamble into a first location in a signal frame and inserting a second synchronization preamble into a second location in a signal frame, in which a first synchronization preamble transmits information indicative of a second location. The method further includes transmitting a signal frame to a receiver in a wireless communication environment.

[012] In accordance with a second general objective, the present invention provides a method for generating a signal frame. The method includes determining a first location in a signal frame in order to insert a first synchronization preamble, and a second location in a signal frame in order to insert a second synchronization preamble, forming a first synchronization preamble, at least in part, based on determining a second location of a second synchronization preamble by inserting the first synchronization preamble into a specific first location in the signal frame, inserting the second synchronization preamble into a specific second m Position in the signal frame and transmitting the signal frame to the receiver in a wireless environment.

[013] In accordance with a third general objective, the present invention provides a transmission device for transmitting a signal frame in a wireless communication environment. The transmitting device includes a control unit used to determine the first location in the signal frame for the first synchronization preamble and the second location in the signal frame for the second synchronization preamble, forming the first synchronization preamble based at least in part on the determination of the second location of the second synchronization preamble by inserting the first a synchronization preamble at a specific first location in the signal frame and inserting a second synchronization preamble at specifically a second location in the signal frame. The transmitting device further includes a transmission circuit of the signal frame to the receiving device.

[014] According to a fourth general objective, the present invention provides a method for receiving a signal frame in a wireless communication environment. The method includes receiving a radio signal containing a plurality of signal frames, in which each signal frame contains a first synchronization preamble and a second synchronization preamble, identifying a first synchronization preamble in a given signal frame, determining at least partially based on information transmitted by the first synchronization preamble the location of the second synchronization preambles in a given signal frame, and for receiving a transmitted overhead message from a combination of the first synchronization preamble and second preamble synchronization.

[015] According to a fifth general objective, the present invention provides a receiver for receiving a signal frame in a wireless communication environment. The receiving device includes a receiver and a control unit. The receiver is used to receive a radio signal containing a plurality of signal frames, in which each signal frame contains a first synchronization preamble and a second synchronization preamble. The control unit is used to identify the synchronization preamble in a given signal frame of the radio signal, determining, at least partially based on the information transmitted by the first synchronization preamble, the location of the second synchronization preamble in this signal frame, and to obtain the transmitted service message from the combination of the first synchronization preamble and second preamble synchronization.

[016] These and other objects and features of the present invention will become apparent to those skilled in the art from an analysis of the following description of specific embodiments of the invention and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[017] In the accompanying drawings:

[018] Figure 1 is a block diagram of a wireless communication system;

[019] Figure 2 is a block diagram of a base station according to a non-limiting example embodiment of the present invention;

[020] Figure 3 is a block diagram of a mobile station according to a non-limiting example embodiment of the present invention;

[021] Figure 4 is a block diagram of a relay station according to a non-limiting example embodiment of the present invention;

[022] Figure 5 illustrates a logical break in the architecture of a transmitter according to a non-limiting example of an embodiment of the present invention;

[023] Figure 6 illustrates the logical breakdown of the receiver architecture according to a non-limiting example embodiment of the present invention;

[024] Figure 7 shows Figure 1 of IEEE 802.16m-08 / 003rl, an example of a common network architecture;

[025] Figure 8 shows Figure 2 of IEEE 802.16m-08 / 003rl, a relay station in a common network architecture;

[026] Figure 9 shows figure 3 of IEEE 802.16m-08 / 003rl, a reference system model;

[027] Figure 10 shows Figure 4 of IEEE 802.16m-08 / 003rl, an IEEE 802.16m protocol structure;

[028] FIG. 11 shows FIG. 5 of IEEE 802.16m-08 / 003rl, a plane for processing IEEE 802.16m IEEE MS / BS data stream;

[029] Figure 12 shows Figure 6 of IEEE 802.16m-08 / 003rl, IEEE MS / BS 802.16m IEEE process flow control plane;

[030] Figure 13 shows Figure 7 of IEEE 802.16m-08 / 003rl, a universal multi-carrier system support protocol architecture;

[031] Figure 14 is an example of a signal comprising frames, subframes, and first and second synchronization sequences;

[032] Figures 15 (a) to (c) are non-limiting representations of the synchronization channel with respect to primary and secondary carrier frequencies;

[033] Figures 16 (a) to (c) are non-limiting representations of the primary and secondary synchronization channels with respect to the primary and secondary carrier frequencies;

[034] Figure 17 illustrates a non-limiting example of a method used by a transmitter to transmit signals in a wireless communication environment; and

[035] Figure 18 illustrates a non-limiting example of a method used by a receiver to receive signals in a wireless communication environment.

[036] Other objectives and features of the present invention will become apparent to ordinary specialists from an analysis of the following description of specific examples of embodiments of the invention with reference to the accompanying drawings.

DETAILED DESCRIPTION

[037] Figure 1 illustrates a base station control center (BSC) 10 that manages wireless communications in a zone of multiple cells 12, and these cells are served by respective base stations (BS) 14. In some configurations, each cell is further divided into multiple sectors or zones 13 (not shown). Basically, each base station 14 facilitates communication using OFDM with mobile and / or wireless terminals 16 that are within a cell 12 associated with a corresponding base station 14. Moving the mobile terminals (MS) 16 relative to the base stations 14 causes significant fluctuations in channel operating conditions. As shown, base stations 14 and mobile terminals 16 may include multiple antennas to provide spatial diversity for communication. In some configurations, relay stations 15 may provide communication between base stations 14 and wireless terminals 16. Wireless mobile terminals 16 may be redirected 18 from any cell 12, sector 13, zone (not shown), base station 14, or relay station (RS) 15 to another cell 12, sector 13, zone (not shown), base station 14 or relay station 15. In some configurations, base stations 14 are connected to each other and to another network (such as a core network or the Internet (not shown) via transpo commercial communications network 11. In some configurations, the control center of the base station 10 is not necessary.

[038] Figure 2 shows an example of a base station 14. A base station 14 typically includes a control unit 20, a group processor 22, a transmitter 24, a receiver 26, multiple antennas 28, and a network interface 30. The receiver 26 receives radio frequency signals carrying information from one or several remote transmitters of mobile terminals 16 (shown in FIG. 3), and relay stations 15 (shown in FIG. 4). A low-noise amplifier and filter (not shown) can be used to amplify the signal and remove broadband interference from the signal for subsequent processing. The down-conversion and digitization circuit (not shown) then converts the resulting filtered signal down-converted to an intermediate or group frequency signal, which is then digitized into one or more digital streams.

[039] The group processor 22 processes the received digitized signal to extract information bits or data bits transmitted in the received signal. This processing typically includes demodulation, decoding, and error correction operation. Group processor 22 is typically implemented in one or more digital signal processors (DSPs) or in specialized integrated circuits (ASICs). The received information is then sent to the wireless network via the network interface 30 or transmitted to other mobile terminals 16 served by the base station 14, either directly or using a relay 15.

[040] On the transmission side, the group processor 22 receives digitized data, which may be speech, data or control information, from the network interface 30 under the control of the control unit 20 and encodes the data for transmission, the encoded data being output to the transmitter 24, where they are modulated one or more carrier signals having a desired frequency or transmission frequencies. A power amplifier (not shown) amplifies the modulated carrier signals to a level suitable for transmission, and the modulated carrier signals arrive at antennas 28 through an appropriate network (not shown). The modulation and processing details are described in more detail below.

[041] Figure 3 shows an example of mobile terminals 16. Similarly to base station 14, mobile terminal 16 will include a control unit 32, a group processor 34, a transmitter 36, a receiver 38, multiple antennas 40, an interface and a user terminal 42. The receiver 38 receives radio frequency signals transmitting information from one or more wireless transmitters, which may be base stations 14 and / or repeaters 15. A low-noise amplifier and filter (not shown) can interact to amplify signals and remove wide out-of-band interference from a signal intended for subsequent processing. A down-conversion and a digitization circuit (not shown) convert the resulting filtered signal down-converted to an intermediate or group frequency signal, and the signal is then digitized into one or more digital streams.

[042] The group processor 34 processes the received digitized signal to extract information bits or data bits transmitted in the signal. This processing typically includes demodulation, decoding, and error correction operations. Group processor 34 is typically implemented in one or more digital signal processors (DSPs) and specialized integrated circuits (ASICs).

[043] For transmission, the group processor 34 receives digitized data, which may be speech, video, data or control information, from the control unit 32 and encodes this data for transmission. The encoded data is output to a transmitter 36, where it is used by a modulator to modulate one or more carrier signals at a desired frequency or transmission frequencies. A power amplifier (not shown) amplifies the modulated carrier signals to a level suitable for transmission and transmits the modulated signal to the carrier antennas 40 through a matching circuit (not shown). As is known to those skilled in the art, various modulation and processing techniques may be used to transmit the signal between the mobile terminal and the base station, directly or indirectly through the relay station 15.

[044] In OFDM modulation, the transmission band is divided into multiple orthogonal carriers. Each carrier is modulated according to the transmitted digital data. Since OFDM divides the transmission band into multiple carriers, the bandwidth per carrier decreases and the modulation time per carrier increases. Since multiple carriers are transmitted in parallel, the transmission rate of digital data or symbols on any given carrier is lower than when a single carrier is used.

[045] OFDM modulation involves the use of Fast Inverse Fourier Transform (IFFT) of transmitted information. When demodulating the received signal, a fast Fourier transform (FFT) is performed to restore the transmitted information. In practice, IFFT and FFT are provided by digital signal processing, including inverse discrete Fourier transform (IDFT) and discrete Fourier transform (DFT), respectively. Thus, a typical sign of OFDM modulation is that orthogonal carriers are formed for multiple bands within a transmission channel. Modulated signals are digital signals having a relatively low transmission rate and capable of staying within their respective bands. Individual carriers are not directly modulated by digital signals. Instead, all carriers are modulated immediately by IFFT processing.

[046] In operation, OFDM is preferably used at least to transmit downlink signals from base stations 14 to mobile stations 16. Each of base stations 14 has “n” transmit antennas 28 (n> = 1), and each of the mobile stations 16 has “m” receiving antennas 40 (m> = 1).

[047] Note that the corresponding antennas can be used for reception and transmission using the corresponding duplexers or switches and are called so for clarity of presentation only.

[048] When relay stations 15 are used, OFDM is preferably used for transmitting downlink signals from base stations 14 to relay stations and from relay stations to mobile stations 16.

[049] Figure 4 shows an exemplary relay station 15. Like the base station 14 and the mobile terminal 16, the relay station 15 has a control unit 132, a group processor 134, a transmitter 136, a receiver 138, multiple antennas 130, and a relay 142. Relay 142 allows a relay station 15 establish communication between one of the base stations 14 and one of the mobile stations 16. The receiver 138 receives radio frequency signals carrying information from one or more base stations 14 and mobile stations 16. Low noise divisor and a filter (not shown) may be used to amplify the signal and remove broadband interference from the signal intended for subsequent processing. A down-conversion and a digitization circuit (not shown) convert the resulting filtered signal down-converted to an intermediate or group frequency signal, and the signal is then digitized into one or more digital streams.

[050) A group processor 134 processes the received digital signal to extract information or data bits transmitted in the signal. This processing typically includes demodulation, decoding, and error correction operations. Group processor 134 is typically implemented in one or more digital signal processors (DSPs) and application specific integrated circuits (ASICs).

[051] For transmission, the group processor 134 receives digitized data, which may be speech, video, data or control information, from the control unit 132 and encodes this data for transmission. The encoded data is output to a transmitter 136, where it is used by a modulator to modulate one or more carrier signals at a desired frequency or transmission frequencies. A power amplifier (not shown) amplifies the modulated carrier signals to a level suitable for transmission and transmits the modulated signal to the carrier antennas 130 through a matching circuit (not shown). As is known to those skilled in the art, various modulation and processing techniques may be used to transmit the signal between mobile stations 16 and base stations 14, directly or indirectly through relay stations 15, as described above.

[052] Figure 5 describes the logical architecture of OFDM transmission. Initially, the control center of the base station 10 sends data that will be transmitted by various mobile stations 16 to the base stations 14, either directly or using one of the relay stations 15. The base stations 14 can use channel quality indicators (CQI) associated with the mobile stations 16 to schedule data for transmission and select the appropriate coding and modulation for transmitting scheduled data. CQI indicators may be provided directly by mobile stations 16 or may be determined by base stations 14 based on information provided by mobile stations. In any case, the CQI for each of the mobile stations 16 is a function of the extent to which the channel amplitude (or response) varies in the OFDM frequency range.

[053] The scheduled data 44, which is a stream scrambled in a manner that reduces the ratio of peak power to average associated with the data using data scrambling logic 46. The cyclic redundancy check (CRC) control for scrambled data is determined and added to the scrambled data, using the add logic of CRC 48. After that, channel coding is performed using channel 50 encoder to efficiently add redundancy to data and facilitate error recovery and correction at mobile stations 16. Channel coding for a specific mobile station 16 is based on CQI. In some implementations, channel 50 encoder uses known turbo coding techniques. The encoded data is then processed by level 52 matching logic to compensate for the data extension associated with the encoding.

[054] The interlace logic 54 systematically reorders the bits in the encoded data to minimize loss of consecutive data bits. The resulting data bits are systematically mapped to the appropriate symbols depending on the selected baseband modulation by the display logic 56. Preferably, quadrature amplitude modulation (QAM) or quadrature phase modulation (QPSK) is used. The degree of modulation is preferably selected based on the CQI for a particular mobile terminal. Symbols may be systematically reordered using symbol rotation logic 58 to further maintain the integrity of the transmitted signal during periodic data loss caused by signal fading.

[055] At this stage, the groups of bits were converted to characters representing locations in the amplitude and phase constellation. When spatial diversity is required, the symbol blocks are processed by the space-time block code (STC) of the logic encoder 60, which changes the symbols in a way that makes the transmitted signals more resistant to interference and easier to be decoded on mobile stations 16. The logical encoder STC 60 will process the incoming symbols and provide " n "outputs corresponding to the number of transmit antennas 28 of the base station 14. The control unit 20 and / or group processor 22 described above with reference to figure 5 provide a control signal displayed To control the STC encoder. Assume that at this stage, the symbols for the "n" outputs are representative of the data that will be transmitted and can be recovered by the mobile stations 16.

[056] For the purposes of this example, assume that the base station 14 has two transmit antennas 28 (n = 2) and a logical encoder STC 60 that provides two output symbol streams. Accordingly, each of the output symbol streams is transmitted to a respective IFFT processor 62, shown separately for ease of presentation. It is clear to those skilled in the art that one or more processors can be used to process such a digital signal in a single processor circuit or in combination with the other processors described herein. The IFFT processor 62 will preferably operate on the appropriate symbols to provide an inverse Fourier transform. The output of the IFFT 62 processor provides symbols in the time interval. The symbols in the time interval are grouped into frames that are connected with the prefix by the logic for inserting the prefix 64. Each of the received signals is converted with increasing frequency in the frequency domain to an intermediate frequency and converted into an analog signal with a corresponding digital conversion with increasing frequency (DUC) and digital-to-analog conversion circuit (D / A) 66. The received analog signals are then simultaneously modulated at the desired radio frequency (RF), amplified and transmitted through the RF circuit 68 to the transmitting antennas 28. Note that the pilot signals known to the intended mobile terminal 16 are scattered among the subcarriers. Mobile terminal 16, which is discussed in detail below, will use pilot signals to estimate the channel.

[057] We now turn to figure 6, illustrating the reception of transmitted signals by one of the mobile terminals 16 either directly from one of the base stations (14 in figure 1), or using a relay 15. Upon arrival of the transmitted signals to each of the receiving antennas 40 of the mobile terminal 16, these signals are demodulated and amplified by the corresponding RF circuit 70. For clarity, only one of these two signal acquisition paths is described in detail. An analog-to-digital converter and a down-conversion (A / D) circuit 72 converts and digitizes the down-converted analog signal for subsequent digital processing. The resulting digitized signal may be used by the automatic gain control circuit (AGC) 74 to control the amplification of amplifiers in the RF circuit 70 based on the obtained signal level.

[058] The original digitized signal is intended for synchronization logic 76, performing the function of coarse synchronization 78, for buffering several OFDM symbols and calculating autocorrelation between two consecutive OFDM symbols. The obtained time indicator, corresponding to the maximum of the correlation result, determines the exact synchronization search window, which is used by the exact synchronization function 80 to determine the starting position of frames based on the headers. The output of the accurate synchronization function 80 facilitates the collection of frames by the cyclic synchronization logic 84. Proper cyclic synchronization is important for subsequent FFT processing to ensure accurate conversion from the time domain to the frequency domain. The exact synchronization algorithm is based on the correlation between received pilots, portable headers, and a local copy of known pilot data. After cyclic synchronization, the OFDM symbol prefix is removed by prefix removal logic 86 and the resulting samples are transferred to the frequency shift / correction function 88, which compensates for the system frequency shift caused by the mismatch between the transmitter and receiver local oscillators. Preferably, the synchronization logic 76 includes a frequency and time offset estimation function 82, which uses headers to estimate the frequency offset and time offset in the transmitted signal, and provides these estimates for the frequency offset / correction function 88 to properly process OFDM symbols.

[059] At this stage, the OFDM symbols in the time slot are ready for frequency domain conversion by the FFT processing function 90. The result is a series of frequency domain symbols that are transmitted to the processing function 92. The processing function 92 extracts the scattered pilots using function 94 to extract the scattered pilot, determines the channel estimate based on the extracted pilot using the channel estimate function 96, and provides a channel response for all subcarriers using the channel reconstruction function 98. To determine tklik channel for each subcarrier, the pilot signal is mainly composed of a plurality of reference symbols that are scattered among the data symbols for all subcarriers of OFDM time and frequency in a known pattern. Next, in FIG. 6, the processing logic compares the received reference symbols with reference symbols that are expected in certain subcarriers at a specific time to determine a channel response for the subcarriers in which the reference symbols were transmitted. The results are interpolated to estimate the channel response for most, if not all, remaining subcarriers for which reference symbols were not provided. The actual and interpolated channel responses are used to estimate the overall channel response, which includes the channel responses for most, if not all, of the subcarriers in the OFDM channel.

[060] The frequency domain symbols and channel reconstruction information that are obtained from the channel responses for each receive path are transmitted to the STC 100 decoder, which provides STC decoding on both receive paths to recover the transmitted symbols. The channel reconstruction information provides correction information to the STC 100 decoder sufficient to remove transmission channel effects when processing corresponding frequency-domain symbols.

[061] The recovered symbols are moved back in a specific order using the symbol rotation logic 102, which corresponds to the transmitter symbol rotation logic 58. Alternating symbols are then demodulated or transmitted to the corresponding bitstream 104. The bits are then alternated using the allocation logic 106, which corresponds to the transmitter bit sequence logic 54. The alternating bits are then processed by the mismatch logic of level 108 and transmitted to the logic of the channel 110 decoder to recover the originally scrambled data and the CRC checksum. Accordingly, the CRC logic 112 removes the CRC checksum, validates the scrambled data in the usual way, and passes it to the descrambling logic 114 for descrambling using the known descrambling code of the base station to obtain the initially transmitted data 116.

[062] In parallel with data recovery 116, a CQI or at least enough information to create a CQI in each of the base stations 14 is determined and transmitted to each of the base stations. As noted above, CQI can be a function of carrier-to-interference (CR), as well as the degree to which the channel response varies across different subcarriers in the OFDM frequency range. For this embodiment, the channel gain for each subcarrier in the OFDM frequency band used to transmit information is compared relative to each other to determine the extent to which the channel gain varies in the OFDM frequency band. Although there are many methods for measuring the degree of change, any method must calculate the standard deviation of the channel gain for each subcarrier over the entire OFDM frequency band used for data transmission.

[063] In some embodiments, the relay station may operate time-sharing using only one transceiver, or alternatively have several transceivers.

[064] Figures 1-6 show a communication system that can be used to implement one exemplary embodiment. It should be understood that the embodiments of the application can be implemented with communication systems having an architecture that is different from a specific example, but which works in a manner that does not contradict the implementation of the embodiments described herein.

[065] Returning now to FIG. 7, a reference model of a network is shown which is a logical representation of a network supporting wireless communication among the aforementioned base stations (BS) 14, MS 16, and RS 15, in accordance with a non-limiting embodiment of the present invention. The network reference model identifies functional objects and control points by which interoperability between these functional objects is achieved. Specifically, the reference network model may include MS 16, a service access network (ASN), and a communications service network (CSN).

[066] An ASN can be defined as a complete set of network functions providing wireless access to a subscriber (eg, an IEEE 802.16e / m subscriber). The ASN may include network elements such as one or more base stations 14 and one or more ASN gateways. An ASN may share several CSNs. ASN can provide the following features:

- Level -1 and level 2 communication with MS 16;

- Transmission of AAA messages to the subscriber’s home network service provider (H-NSP) for authentication, authorization and accounting of the subscriber’s communication session;

- Opening a network and choosing a preferred NSP subscriber;

- Repeater functions for establishing level 3 communication (L3) with MS 16 (for example, IP address allocation);

- Radio resource management.

[067] In addition to the above functions for the portable and mobile environment, the ASN may further support the following functions:

- ASN-related mobility;

- CSN-related mobility within the sector;

- paging;

- ASN-CSN communication.

[068] For its part, a CSN can be defined as a series of network functions that provide IP communication services to a subscriber. CSN can provide the following features:

- IP address of the MS and the allocation of the endpoint parameter for user communication sessions;

- AAA proxy or server;

- policy and access control based on the user's subscription profile;

- tunnel support for ASN-CSN;

- charging and settlement of disputes between the subscriber and the operator;

- inter-CSN tunneling for roaming;

- inter-ASN mobility.

[069] The CSN can provide services, such as location-based services, peer-to-peer communication, configuration, authorization and / or communication with IP multimedia services. The CSN may further include network elements such as routers, AAA proxies, user databases, and a gateway for interworking mobile stations. In the context of IEEE 802.16m, the CSN can be deployed as part of the IEEE 802.16m NSP or as part of the mandatory IEEE 802.16e NSP.

[070] In addition, RS 15 can be deployed to provide improved coverage and / or increased performance. With reference to FIG. 8, BS 14, which may support legacy RSs associated with legacy RSs in the “legacy protocol area”. Base station 14 is not required to support the legacy protocol in the “16m zone”. The draft relay protocol may be based on the IEEE 802-16] project, although it may be different from the IEEE 802-16j protocols used in the legacy zone.

[071] Figure 9 shows a reference model of a system that is applicable to both MS 16 and BS 14 and includes various functional units, including a common portion of a medium access control (MAC) sublayer, a convergence sublayer, a security sublayer, and a physical layer ( PHY).

[072] The convergence sublevel maps external network data received through SAP CS to MAC SDUs, received by CPS MAC through SAP MAC, classification of external network SDUs and their association with SFDD MAC, and caller identification, payload header suppression / compression (PH )

[073] The security sublayer performs authentication and secure key exchange and encryption.

[074] The physical layer performs the protocol and functions of the physical layer.

[075] The general portion of the MAC sublayer will now be described in more detail. First, remember that Media Access Control (MAC) is connection oriented. That is, in order to display the operation of MS 16 and the corresponding variable QoS levels, data transmission is performed in the context of “connections”. In particular, “service flows” may be provided when the MS 16 is installed in the system. After MS 16 is registered, connections are associated with these service flows (one connection per service stream) to provide a reference value from which bandwidth can be requested. Additionally, new connections can be established when the customer needs services to change services. A connection defines both the transformation of data between peer convergence processes that use the MAC, as well as the flow of services. The service flow determines the QoS parameters for the MAC protocol data units (PDUs) exchanged over the connection. Thus, service flows are an integral part of the bandwidth allocation process. Specifically, the MS 16 requests uplink bandwidth based on the connection (implicitly identifying the service flow). Bandwidth can be provided by the BS MS as a grant provided in response to a request from the MS to establish a connection.

[076] With further reference to FIG. 10, a common portion of a MAC sublayer (CPS) is classified in a radio resource control function (RRCM) and a medium access control (MAC) function.

[077] RRCM functions include several function blocks that are associated with resource radio functions, such as:

- Radio resource management

- Mobility Management

- Network login management

- location management

- Management in idle mode

- Security Management

- System configuration management

- MBS (Multicast and Alert Service)

- Service flow and connection management

- Repeater functions

- Self-organization

- Multi-carrier mode

Radio resource management

[078] Radio resource management adjusts the parameters of the radio network based on traffic load and also includes a load control function (load balancing), access control and interference control.

Mobility management

[079] The mobility management unit supports functions related to the topology of the Intra-RAT / Inter-RAT network, which includes advertising and measurement, candidate management of BS / RS target neighbors, and also decides whether the MS Intra-RAT / Inter-RAT transmits between cells.

Network Entry Management

[08O] The network entry control unit is responsible for access and initialization procedures. The network entry control unit may generate control messages that are necessary during access procedures, i.e. ranking, coordination of key features, registration, and so on.

Location management

[081] The location control unit is responsible for supporting location-based services (LB). The location control unit may generate messages, including information about the LBS.

Idle control

[082] The control unit in idle mode controls the process of updating location information during idle mode. The idle control unit controls the idle mode operation and generates an alert message based on the alert message from the main network operator.

Security management

[083] The security control unit is responsible for authentication / authorization and key management for secure transmission.

System configuration management

[084] The system configuration control unit controls system configuration parameters and transmits MS configuration information.

MBS (Multicast and Alert Service)

[085] Multicast and notification service (MBS) blocks control messages of controls and data associated with broadcast and / or multicast messages.

Service Flow and Connection Management

[086] The service flow control and connection control unit allocates “MS identifiers” (or station identifiers — STIDs) and “flow identifiers” (FIDs) during access / handover procedures to create service flow procedures. MS and FID will be discussed below.

Repeater Functions

[087] The repeater function block includes support functions for the repeater mechanism. Functions include procedures for supporting the repeater path between the BS and RS during the access process.

Self-organization

[088] The self-organization unit performs the functions of supporting self-configuration and self-optimization mechanisms. Functions include procedures, requesting RS / MS to report measurements for self-configuration and self-optimization and to receive measurement results from RS / MS.

Multi-carrier mode

[089] The multi-carrier (MS) mode unit allows a common MAC entity to control PHY spanning multiple frequency channels. Channels can have different bandwidths (for example, 5, 10 and 20 MHz), be on continuous frequency ranges or ranges consisting of several non-adjacent sections. Channels can have the same or different duplex modes, for example FDD, TDD or a mixture of bidirectional connections and transmission on only one carrier. For continuous frequency channels, the overlapping guard subcarriers are aligned in the frequency domain for use in data transmission.

[090] Media Access Control (MAC) includes functional blocks that relate to the physical layer and channel controls, such as:

- PHY Management

- control signals

- Standby control

- QoS

- Resource planning and compaction

- ARQ

- Fragmentation / packaging

- MAC PDU Formation

- Coexistence of several radio devices

- data redirection

- Interference control

- Coordination of joint work of base stations

PHY Management

[091] the PHY control unit controls PHY signaling processes such as location, measurement / feedback (CQI) and HARQ ACK / NACK. Based on the CQI and HARQ ACK / NACK, the PHY control unit evaluates the quality of the channel arriving at the MS and performs channel adaptation through the modulation and coding correction (MCS) circuit and / or power level. In the ranking procedure, the PHY control unit performs uplink synchronization with power, frequency offset, and estimate of the synchronization offset.

Control signals

[092] The signal control unit generates resource allocation messages. The standby signal control unit controls the operation of the standby descriptor.

Standby Control

[093] The standby control unit may also generate MAC signals related to standby operation, and may communicate with a compaction and resource scheduling unit for proper standby operation.

QoS

[094] The QoS block controls the QoS process based on input of QoS parameters from the service flow and connection control unit for each connection.

Resource Planning and Compaction

[095] The resource scheduling and densification unit schedules and condenses packets based on connection properties. To reflect the properties of the connections, the resource scheduling and compaction unit receives QoS information from the QoS block for each connection.

Aro

[096] The ARQ block performs the function of MAC ARQ. To support ARQ connections, the ARQ block logically divides the MAC SDU into ARQ blocks and the numbers of each logical ARQ block. The ARQ unit may also generate ARQ control messages, for example, a feedback message (ACK / NACK information).

Fragmentation / Packing

[097] the Fragmentation / packaging unit performs fragmentation or packaging MSDU based on the planning results received from the planning unit and resource compaction.

MAC PDU Formation

[098] The MAC PDU generation unit creates a MAC PDU so that BS / MSs can transmit user traffic or control messages to the PHY channel. The MAC PDU generating unit adds a MAC header and can add subtitles.

Coexistence of multiple radio devices

[099] The coexistence unit of several radio devices performs the functions of supporting parallel operations of the IEEE 802.16m and 802.16m non-IEEE radio devices located at the same mobile station.

Data Forwarding

[0100] The data forwarding unit performs the functions of forwarding when RSs are present on the path between the BS and the MS. The data forwarding unit may interact with other units, such as a resource scheduling and multiplexing unit and a MAC PDU.

Jamming control

[0101] The interference monitoring unit performs the functions of monitoring interference between a cell and a sector. Operations may include:

- Work at the MAC level

- Sending a measurement and interference assessment report through the MAC signaling system

- Reduce interference by scheduling and flexible frequency reuse

- Work at the physical level (PHY)

- Transmission power control

- Interference randomization

- Remove interference

- Measurement of interference

- Transmitter beamforming and precoding

Coordination of collaboration of base stations

[0102] The coordination unit of the joint work of the base stations performs the functions of coordinating the actions of multiple BSs, exchanging information, for example, with an interference control unit. Functions include procedures for exchanging information, for example, about monitoring interference between BS stations by signaling on a trunk and MS MAC messaging. Information may include interference characteristics, such as interference measurements, etc.

[0103] Turning now to FIG. 11, a user traffic data stream and processing at BSs 14 and MS 16 are shown. Dotted arrows show user traffic data stream from a network layer to a physical layer and vice versa. On the transmission side, the network layer packet is processed by the convergence sub-layer, the ARQ function (if any), the fragmentation / packing function, and the MAC PDU generation function to form the MAC PDU that will be sent to the physical layer. At the receiving side, the physical layer SDU is processed by the MAC PDU generation function, fragmentation / packing function, ARQ function (if any), and the convergence sub-layer function to form network layer packets. Solid arrows indicate controls among the CPS functions and between CPS and PHY that relate to the processing of user traffic data.

[0104] Turning now to FIG. 12, the CPS controls the signal flow and signal processing in BS 16 and MS 14. On the transmission side, the dashed arrows indicate the signal flow in the control plane from control plane functions to data plane and flow processing functions signals in the control plane of the functions of the data plane to ensure appropriate distribution of MAC signals (eg, MAC control messages, MAC header / subtitle), for transmission over the air. On the receiving side, the dashed arrows show the processing of the received MAC broadcast signals by the data plane functions and the reception of the corresponding control plane signals as a function of the control plane. The solid arrows show the controls among the CPS functions and between CPS and PHY, which relate to the processing of the control plane signals. The solid arrows between M_SAP / C_SAP and the MAC function blocks show elements of a network management system and a management system (NCMS). Elements coming to and from M_SAP / C_SAP determine the functionality of the network, such as interference control during joint operation of base stations, mobility management inter / intra RAT, etc., and management-related functionality, such as location management, system configuration and etc.

[0105] We now turn to Figure 13, which shows the architecture of the original protocol to support a multi-carrier system. A common MAC entity can control a PHY spanning multiple frequency channels. Some MAC messages sent on one carrier may also apply to other carriers. Channels can have different bandwidths (for example, 5, 10 and 20 MHz), be on continuous frequency ranges or ranges consisting of several non-adjacent sections. Channels can have the same or different duplex modes, for example FDD, TDD or a mixture of bidirectional connections and transmission on only one carrier.

[0106] A common MAC entity can simultaneously support the presence of MS 16 with various capabilities, such as operating on a single channel only once or continuously through adjacent or non-adjacent channels.

[0107] In OFDM and OFDMA wireless communication systems, and any mobile station 16 that intends to enter the system must establish time and frequency synchronization with the base station 14, which transmits signals, and also obtain identification information (such as an identifier (ID) cell) of the transmitting device, which in most cases is the base station 14. Thus, the mobile station 16 must synchronize with the base station 14 and obtain certain parameters of the base station, such as the cell ID. A cell identifier is usually obtained by detecting a preamble used by a particular base station 14, which is inserted into each signal frame transmitted from the base station 14. Although the transmitting device will be described here as the base station 14, it should be understood that the transmitting device can also be a relay station 15 .

[0108] Basically, the preambles can provide at least one of the following operations: quick access to the base station, identification / selection of the base station and C / 1 ratio measurement, frame and time synchronization, time shift estimation, initial channel estimation. Ideally, a frame preamble is designed to minimize costs and provide high spectral efficiency and high performance radio systems.

[0109] Due to the increase in channel bandwidth in wireless broadband access, as well as the increase in FTT volume, searching for the preamble in the received signal may require high computational complexity on the side of the mobile station 16.

[0110] In developed versions of wireless communication systems such as 802.16m, the frame structure is such that a new preamble configuration is required. For this configuration, it is necessary to provide relative timing of the primary secondary preambles using the primary synchronization channel to transmit other information to the mobile phone (including time / location signals of the secondary preamble, group ID (specifically, the ID of the group of localized cells), bandwidth and / or multi-carrier structure , parameters of an outdated system, other information useful for a mobile phone), structure and / or position of synchronization channels relative to multi-carrier structures, with specific code structure for mobile base / relay stations; relative timing options for preambles and superframe header.

[0111] In accordance with one example embodiment of the present invention, each frame in the OFDM signal has at least a first preamble and a second preamble. The first preamble is designed so that the general search for the first preamble and second preamble is relatively fast and requires less computation than existing preamble calculation projects. The first preamble and the second preamble can be used for coarse synchronization and frame synchronization, cell identification and frequency synchronization. The first and second preambles can also support the frequency domain with accurate frequency synchronization. In addition, control information is transmitted to the preamble, reducing the synchronization ambiguity of the primary and secondary synchronization channels, the number of cell IDs increases, and the ambiguity decreases when placing the preamble with many carriers. Although the first and second preambles are described below for clarity, it should be understood that the present invention could also be implemented with three or more preambles in the signal frame.

[0112] As will be described in more detail below, the first preamble and the second preamble provide the first and second synchronization sequences that allow the mobile station to access a base station or multiple base stations. At least one of the first and second preambles may coexist with an obsolete preamble or replace an obsolete preamble. The term "obsolete preamble" refers to a known preamble in an OFDMA frame, as described in IEEE802.16-2004.

[0113] The first preamble includes a first synchronization sequence capable of transmitting information. According to a non-limiting example, at least a portion of the first synchronization sequence is capable of transmitting a "cell group ID" that is associated with a group of base stations. A group of base stations can be combined based on geography or a common characteristic, such as a group of mobile base stations, among other possible names.

[0114] As will be described in more detail below, the first synchronization sequence of the first preamble may also transmit additional information related to various attributes or parameters associated with the transmitting base station 14, or to a specific group of base stations to which the transmitting base station 14 belongs. The first synchronization sequence may also contain certain control information that is intended to be transmitted to the mobile device 16.

[0115] The second preamble includes a second synchronization sequence that transmits information indicative of a "local identifier" associated with transmitting base station 14 in a group of base stations. When combined, the first synchronization sequence and the second synchronization sequence transmit a unique cell identifier to the transmitting base station. The combination of the first synchronization sequence and the second synchronization sequence can also transmit certain control information to the mobile device 16.

[0116] Figure 14 shows a non-limiting example of an OFDM signal 1400 used in the present invention. This OFDM 1400 signal is sent as a plurality of consecutive OFDM 1402 frames or blocks, which typically contain 1000 data bits. Each OFDM frame 1402 includes a number of subframes, which are numbered 1404a-e in the non-limiting example given here. It should be understood that each OFDM frame 1402 could include a different number of subframes 1404. Subframes are allocated for preambles, headers, or OFDM symbols, as will be described in more detail below. In addition, subframes may be on different subcarriers. The structure may be similar to the structure proposed in 802.16m, which is assumed to be similar to the structures that will be developed in 3GPP and 3GPP2 technologies.

[0117] In the example shown in FIG. 14, subframe 1404a contains a first preamble that includes a first synchronization sequence 1406, and subframe 1404c contains a second preamble that includes a second synchronization sequence 1408. Subframe 1404b contains a header. Subframes 1404d and 1404e comprise OFDM symbols that are used in transmitting voice, video, control information, or any other information that needs to be transmitted to the receiving mobile station 16 over a wireless network.

[0118] It should be understood that the relative position or location of the preambles, header, and OFDM signals in the OFDM frame may be fixed for each OFDM frame or may vary from one OFDM frame to another. In some cases, the first preamble ("preamble 1") may be sent on the first subframe and the second preamble ("preamble 1") may be sent on the second subframe. Alternatively, a second preamble may be placed before the first preamble. For example, in some embodiments, the first preamble is sent immediately on the subframe after the subframe containing the second preamble. In alternative embodiments, the header is sent immediately on the subframe after the second preamble. In some cases, the title is the title of the superframe so that it is not included in each frame and instead is included only in every fourth or fifth frame, for example. In such a situation, the first preamble and the second preamble can be adjacent to each other or separated by subframes containing OFDM symbols.

[0119] Given that the relative position of the first and second preambles may change in accordance with the present invention, the first preamble is used to transmit information indicating the location within the second preamble. Thus, when OFDM frames are received at the mobile station 16, it is easier and faster for the receiving mobile station 16 to locate the first and second preambles.

[0120] Information indicating the location or relative position of the second preamble in the OFDM frame typically passes through the first synchronization sequence of the first preamble. More specifically, the first synchronization sequence may transmit information indicating the location of the second preamble in the OFDM frame. The first synchronization sequence may transmit information indicating relative timing between the first preamble and the second preamble, or the first synchronization sequence may transmit information indicating a shift or relative position between the first preamble and the second preamble. Based on this information, the mobile station 16, which receives the OFDM signal, can quickly determine where to look in the OFDM frame for the second preamble, which significantly reduces the time and amount of computation required to find the second preamble; establish synchronization with the base station 14 and identify the unique cell identifier of the transmitting base station 14.

[0121] As mentioned above, the first preamble carries information indicating the location in the OFDM frame of the second preamble using the first synchronization sequence. In one non-limiting example, the first preamble can use 1 of 40 synchronization sequences, in which the synchronization sequence consists of the first part, which provides 1 out of 10 possible “cell group identifiers”, and the second part, which provides 1 out of 4 possible shifts between the first preamble and the second preamble. As such, the synchronization sequence is composed of a first part that provides a "cell group ID" of the group of base stations to which the transmitting base station belongs, and a second part that provides an indication of a "shift" between the first preamble and the second preamble. When transmitting the “shift” signal, the receiving mobile station 16 will not have to search for each subframe position for the second preamble. Instead, the mobile station 16 will know exactly where to look, thereby reducing the complexity of the search.

[0122] It should be understood that the first preamble may use any number of synchronization sequences and that the first part is not limited to 1 out of 10 sequences. In addition, instead of the second part of the synchronization sequence providing an indication of a “shift” between the first preamble and the second preamble, the second part of the synchronization sequence can provide an indication of relative timing between the two preambles.

[0123] The first synchronization sequence may further include a third part, which transmits other information, which may be control information or information indicating an attribute or parameter associated with a group of base stations. The third part may also transmit information indicating the relative position of the common header or the header of the superframe or the relative position between the first preamble and the outdated frame, among other possibilities.

[0124] As mentioned above, the second preamble includes a second synchronization sequence that transmits a "local identifier" associated with the transmitting base station in the group of base stations. For example, a second synchronization sequence may use 1 of 114 sequences (or any other possible number of sequences), each of which is respectively associated with a base station in a group of base stations. Similarly, when the first part of the first synchronization sequence (which indicates the group of base stations) is combined with the second synchronization sequence (which indicates the transmitting base station in the group), a common cell identifier will be obtained.

[0125] The second synchronization sequence may simply transfer the local identifier of the transmitting base station 16 or, alternatively, may also carry additional information. For example, the second synchronization may comprise a first part that carries the “local identifier” of the transmitting base station 16, and a second part that carries additional information, such as control information, or a part of control information, which, when combined with part of the first synchronization sequence, transmits control information.

[0126] In accordance with a non-limiting embodiment, the first synchronization sequence belongs to the first set of synchronization sequences, and the second synchronization sequence belongs to the second set of synchronization sequences. The first set of synchronization sequences is preferably smaller than the second set of synchronization sequences to facilitate the search for the first preamble. In the above example, the first synchronization sequence belongs to a series of 40 synchronization sequences and the second synchronization sequence belongs to a series of 114 synchronization sequences. This provides a quick search for the main sequence, and, given that the main sequence provides a location in the signal frame of the second preamble, the total time and complexity of the search for the first and second preamble are significantly reduced.

[0127] As mentioned above, the first synchronization sequence includes at least a portion that transmits a "Cell Group ID". Also, a group of base stations (such as a cluster of local base stations) shares a common part of the first synchronization sequence. In addition, part of the synchronization sequence of the "cell group identifier" is characteristic of each base station of this group of base stations. The synchronization of the mobile station 16 with the transmitting base station 14 can be facilitated by macro diversity, in which all base stations in the group of base stations provide signal frames having the same sequence of "cell group identifiers" simultaneously on the same resources. When all base stations 14 in the base station groups transmit the same sequence of "cell group identifiers" IDs simultaneously, the receiving mobile station 16 can identify the usually issued sequence and, thus, the first preamble without difficulty. Once the first preamble has been identified, the receiving mobile station 16 can then identify the location of the second preamble in the OFDM signal frame, which provides a “local identifier” of the transmitting base station, so that base stations in groups can be differentiated. The receiving mobile station 16 then obtains a unique cell identifier of the transmitting base station 14.

[0128] Returning to Figure 1, we see that some of the base stations 14 and / or repeaters 15 may be mobile, so that they are mobile transmitters. In accordance with one non-limiting embodiment, mobile base stations 14 and / or repeaters 15 may be associated with a “cell group identifier sequence”. In addition, one or more “cell group identifiers” from the set of “cell group identifiers” can be reserved for these mobile transmitters so that they can be distinguished from the fixed base stations 14 and the repeaters 15. Thus, the mobile station 16 that receives the signals from these mobile transmitters, may find that they are moving based on a sequence of "cell group identifiers". The sequence of “cell group identifiers” may be associated with mobile base stations 14 and repeaters 15 or with mobile base stations 14 and mobile repeaters 15, or the mobile base stations 14 and mobile repeaters 15 may be associated with different sequences of “cell group identifiers”, so that the receiving mobile station 14 can detect whether it received a message from the base station 14 or from the relay 15.

[0129] In order to further simplify and facilitate the search and initial detection of preambles, the first and second preambles may be limited to transmission on a single frequency or transmission on several carrier frequencies in predetermined ways. For example, at least part of one of the first and second preambles can be carried by the synchronization channel if the following conditions are met:

- the synchronization channel may be limited to a fixed bandwidth at the carrier frequency, which may be the minimum carrier frequency. For example, a synchronization channel may be fixed in the 5 MHz band;

- the synchronization channel can be limited only to the primary carrier, which can transfer control information;

- the synchronization channel may be limited by the alignment of one edge of the carrier; and

- in embodiments with many carriers, the synchronization channel may be limited to transmission only at the smallest of the many carrier frequencies.

[0130] Figures 1 (a) to 15 (c) show some graphical representations of a synchronization channel with respect to one or more carrier channels, which illustrate the aforementioned limitations. As shown in FIG. 15 (a), the synchronization channel has the same bandwidth as the primary carrier frequency (which is limited to the 5 MHz band) and aligned at both edges of the primary carrier frequency. 15 (b) shows a primary carrier frequency that has a bandwidth higher than the synchronization channel. The synchronization channel has a fixed bandwidth and is aligned on one edge of the primary carrier frequency. The synchronization channel is carried on the primary carrier frequency, which can carry control information. The secondary carrier frequency is shown without a synchronization channel. As described here, the primary carrier frequency can carry control information, while the secondary carrier frequency does not. Figure 15 (c) shows two primary carrier frequencies. The synchronization channel is carried on the smallest of the two primary carriers, and the secondary carrier does not have a synchronization channel. In an alternative embodiment, both primary carrier frequencies may carry a synchronization channel. In this case, the first primary carrier has a larger bandwidth than the synchronization channel.

[0131] In yet another embodiment, at least a portion of the first and second preambles can be carried by the primary and secondary synchronization channel, which are transmitted on one or more carriers according to predetermined conditions. For example, the primary and secondary synchronization channels must meet the following conditions:

- the primary synchronization channel may be limited to a fixed bandwidth, which may be a minimum carrier frequency, such as 5 MHz. At the same time, the secondary synchronization channel may have a higher passband, which includes the entire passband of the carrier frequency;

- primary and secondary synchronization channels can be limited by the presence only on the primary carrier frequency, which can carry control information. However, in alternative embodiments, the secondary synchronization channel may be present at all carrier frequencies;

- the primary synchronization channel may be limited by alignment along one edge of the carrier frequency; and

- in multi-carrier embodiments, the primary synchronization channel may be limited to transmission only at the smallest of the multiple carrier frequencies, while the secondary synchronization channel may be present at all carrier frequencies.

[0132] Figures 16 (a) to 16 (c) show some graphical representations of the primary and secondary synchronization channels with respect to one or more channels of the carrier frequency. As shown in FIG. 16 (a), the first and second synchronization channels have the same bandwidth (which is limited to the 5 MHz band) as the primary carrier frequency. In addition, the first and second synchronization channels are aligned at the edges of the primary carrier frequency. Figure 16 (b) shows the primary and secondary synchronization channels that are carried on the primary carrier frequency. The primary synchronization channel is limited to a bandwidth of 5 MHz, while the secondary synchronization channel has a large bandwidth, which is the bandwidth of the primary carrier frequency. The primary and secondary synchronization channels are aligned on one edge of the primary carrier frequency. 16 (c) shows an embodiment with several channels in which a secondary synchronization channel is carried by the larger of the two primary carrier frequencies and a primary synchronization channel is carried by one of the two primary carrier frequencies. The secondary carrier frequency is shown without a synchronization channel.

[0133] Below, with reference to figures 2 and 17, a method is described in which a signal frame comprising a first preamble and a second preamble is formed. In figure 2, one or more processing modules in the control unit 20 and / or group processor 22 can determine where the first and second preambles should be located in the signal frame, and generates the first and second preambles to transmit at least part of the above information to a receiving device such as mobile station 16.

[0134] Figure 17 is a flowchart illustrating a process used by one or more processing modules to form and place the first and second preambles in the signal frame. First, in step 1702, the process includes determining a first location in the signal frame where the first preamble should be located, and determining a second location in the signal frame where the second preamble should be located. This determination can be made based on many criteria, such as frame length, channel conditions, whether or not the superframe header is enabled, etc. As mentioned above, the second preamble may be located in the signal frame in place prior to the first preamble.

[0135] In step 1704, the process includes forming a first preamble. As mentioned above, the first preamble contains a first synchronization sequence that includes at least a first part that provides a "cell group ID" and a second part that provides information indicating the location of the second preamble in the signal frame. As such, the first preamble is formed at least in part based on the location of the second preamble.

[0136] The first part of the first synchronization sequence, which provides a "cell group ID", may be known to the base station, and a synchronization sequence indicating a "cell group ID" is included in each signal frame that is issued by the base station 14. Alternatively, it is possible that the synchronization sequence associated with the "Cell Group ID" is issued by the base station control center to the base station. In yet another alternative, it is possible to access the lookup table (local or remote) to determine the synchronization sequence associated with the “cell group ID” that the transmitting base station belongs to. In the case where access to the lookup table is available, the synchronization sequence associated with the “ID group of cells, "may be determined based on the identifier of the group of cells, the characteristics of the transmitting base station, such as the geographical coordinates of the base station, the local identifier of the base station, or any other therefore a possible characteristic or attribute known transmitting base station.

[0137] The second part of the first synchronization sequence, which provides information indicating the location in the signal frame of the second preamble, is set based on the location determined in step 1702 for the second preamble. For example, another part of the sequence is associated with each of the various possible locations in the signal frame, where the second preamble may be located. In the above example, the second preamble may be located at 1 of 4 different shift positions relative to the first preamble. Each of the shift positions can be associated with a corresponding part of the four possible parts of the synchronization sequence. As such, based on the position of the shift, the corresponding part of the synchronization sequence is determined and added to the first synchronization sequence. The corresponding part of the synchronization sequence can be determined based on a lookup table (local or remote) that displays different shift positions to different parts of the synchronization sequence.

[0138] Although the above is an example of a shift between the first preamble and the second preamble, it should be understood that other parts of the synchronization sequence can be used to convey relative timing between the first preamble and the second preamble.

[0139] The process of generating the first preamble may further include adding additional information that contains various attributes and / or properties of the transmitting base station or group of base stations to which the transmitting base station belongs. The first preamble may also convey control information. This additional information transmitted by the first preamble can be transferred through other parts of the synchronization sequence, among other possibilities.

[0140] In step 1706, the first preamble is inserted into the signal frame at the first location determined in step 1702, and in step 1708, the second preamble is inserted into the signal frame at the second location determined in step 1702. The second preamble is formed in much the same way as first preamble. As described above, the second preamble includes a second synchronization sequence that transmits a local identifier associated with the transmitting base station. This second synchronization sequence, indicating a local identifier, may be known by the transmitting base station, so that it is inserted into each signal frame that is issued by the base station 14.

[0141] Finally, in step 1710, after the signal has been modulated appropriately, the signal frame is transmitted to the receiving mobile station 16 over a wireless network.

[0142] The radio signal that travels wirelessly from the transmitting base station is transmitted to the receiving mobile station 16. Below, with reference to Figures 3 and 18, a method is described in which the signal frame is processed at the receiving mobile station 16.

[0143] Returning to Figure 3, where the receiver 38 receives the signals transmitted over the wireless network and transmits these signals to the group processor 34. One or more processing modules in the control unit 32 and / or the group processor 34 can then find and identify the first and the second preamble contained in this signal frame.

[0144] The flowchart shown in FIG. 18 illustrates a process for obtaining and identifying the first and second preambles in a signal frame. First, in step 1802, a radio signal containing a plurality of signal frames is supplied to a receiver 38. Each of the signal frames contains a first preamble and a second preamble. At step 1804, one or more processing modules in the group processor 34 and / or in the control unit 32 identifies the first synchronization preamble in the signal frame. The identification of the first synchronization signal can be done by identifying a repeating synchronization sequence (which, at least, will be part of the first synchronization sequence) that is contained in each of the signal frames.

[0145] As mentioned above, the first synchronization sequence may be 1 of the 40 possible synchronization sequences that are known to the receiving mobile station 16. Essentially, the receiving mobile station will “view” the reappearing parts of these known sequences in the received signals. Once one of the sequences in the signal frame is detected, the receiving mobile station 16 will know that the first preamble has been detected and that synchronization in frequency and time can be performed. In addition, as soon as the first synchronization sequence is detected, the receiving mobile station 16 can determine the "Cell Group ID" and the location of the second preamble.

[0146] According to the embodiment described above, the first synchronization sequence includes a first part that provides a "cell group ID" and a second part that provides an indication of the location of the second preamble. According to one non-limiting embodiment, the receiving mobile station 16 may compare the first synchronization sequence (or its first and / or second parts) with known sequences contained in the search table that display synchronization sequences (or parts thereof) with cell group identifiers and with different shift or synchronization locations in the signal frame. By comparing the detected first synchronization sequence (or parts thereof) with the sequences contained in the search table, it is possible to determine the “cell group ID” and the shift or synchronization between the first and second preambles. Alternatively, the first part of the synchronization sequence itself may be a "cell group identifier". The location of the second preamble in the signal frame is identified based on information transmitted by the first preamble, and specifically based on information carried by at least a portion of the first synchronization sequence.

[0147] Thus, in step 1806, the location of the second preamble in the signal frame can be identified based on information transmitted by the first preamble. This greatly reduces the search complexity associated with identifying the location of the second preamble. Once the location has been identified, the receiving mobile station 16 can access the second preamble, which transmits information indicating a local identifier. More specifically, information indicative of a local identifier of a transmitting base station may be carried by a second synchronization sequence. The local identifier of the transmitting base station can be a second synchronization sequence or can be found in the search table, which displays the known second synchronization sequences with the corresponding local identifiers of various transmitting base stations in the group of base stations associated with the identifiers of the group of cells.

[0148] In step 1808, once the first and second preambles have been identified, the transmitted signaling information can be extracted from a combination of the first preamble and the second preamble. In accordance with one non-limiting embodiment, the transmitted signaling information may be a unique cell identifier of the transmitting base station 14.

[0149] Although the present invention has been described in detail with reference to the drawings in the form of certain preferred examples of its embodiment, changes and improvements are possible without departing from the spirit and scope of the invention. Therefore, the scope of the invention should be limited only by the claims presented here.

Claims (31)

1. A method for transmitting data in a signal frame, comprising the steps of:
(a) inserting the first synchronization preamble at the first location in the signal frame;
(b) inserting the second synchronization preamble into a second location in the signal frame, wherein information indicating the second location is transmitted in the first synchronization preamble;
(c) transmitting the signal frame to a receiver in a wireless communication environment. 2. The method according to claim 1, wherein the signal frame is an orthogonal frequency division multiplexing (OFDM) signal frame. 3. The method according to claim 1, in which information indicating the second location is transferred through the first synchronization sequence. 4. The method according to claim 3, in which in the first synchronization sequence information is transmitted indicating the relative timing between the first synchronization preamble and the second synchronization preamble. 5. The method according to claim 3, in which information indicating a shift between the first synchronization preamble and the second synchronization preamble is transmitted in the first synchronization sequence. 6. The method according to claim 3, in which in the first synchronization sequence information is additionally transmitted indicating the identifier of the group of transmitting devices, the signal frame being transmitted to the receiving device by a specific transmitting device belonging to this group of transmitting devices. 7. The method according to claim 6, in which all of the aforementioned group of transmitting devices transmit the first synchronization sequence at the same time. 8. The method according to claim 3, in which the first synchronization sequence further transmits information indicating at least one of the relative timing and the relative position of the broadcast header with respect to the first synchronization preamble. 9. The method according to claim 3, in which in the first synchronization sequence information is additionally transmitted indicating at least one of the relative timing and the relative position of the outdated frame with respect to the first synchronization preamble. 10. The method according to claim 6, in which information indicating the local identifier of said specific transmitting device belonging to said group of transmitting devices is transmitted in a second synchronization preamble. 11. The method of claim 10, wherein information indicating a local identifier of said specific transmitter is transferred by a second synchronization sequence. 12. The method of claim 11, wherein, in a combination of a first synchronization sequence and a second synchronization sequence, a cell identifier of a specific transmitter is transmitted, which provides a signal frame to the receiver. 13. The method according to claim 11, in which at least one of the first synchronization sequence and the second synchronization sequence control information is transmitted. 14. The method of claim 9, wherein the first synchronization sequence belongs to the first sequence set and the second synchronization sequence belongs to the second sequence set, wherein the first sequence set is smaller than the second sequence set. 15. The method according to claim 6, in which at least a portion of the first synchronization sequence indicates that said group of transmitting devices is a group of mobile transmitting devices. 16. The method according to 14, in which at least one synchronization sequence in the first sequence set is associated with a group of mobile transmitting devices. 17. The method according to claim 1, wherein the first synchronization preamble and the second synchronization preamble are transmitted at a carrier frequency, wherein at least one of the first synchronization preamble and the second synchronization preamble is limited to a fixed carrier bandwidth. 18. The method according to 17, in which the fixed bandwidth is identical to the bandwidth of the carrier frequency. 19. The method according to 17, in which the fixed bandwidth is less than the bandwidth of the carrier frequency. 20. The method according to claim 19, in which the fixed bandwidth is aligned along the edge of the carrier frequency. 21. The method according to 17, in which the first synchronization preamble and the second synchronization preamble are transmitted at a predetermined one of two carrier frequencies, this predetermined one of these two carrier frequencies being adapted to transmit control information. 22. The method according to 17, in which at least one of the first synchronization preamble and the second synchronization preamble is transmitted at least of the two carrier frequencies. 23. A method for generating a signal frame, comprising the steps of:
(a) determining a first location in the signal frame for inserting the first synchronization preamble and a second location in the signal frame for inserting the second synchronization preamble;
(b) generating a first synchronization preamble based at least in part on said specific second location of the second synchronization preamble;
(c) inserting a first synchronization preamble into said specific first location in the signal frame;
(d) inserting a second synchronization preamble into said specific second location in the signal frame;
(e) initiate the transmission of the signal frame to the receiver in a wireless communication environment. 24. The method according to item 23, in which the determination of the first location in the signal frame and the second location in the signal frame is performed, at least in part, based on the length of the frame and channel conditions. 25. The method according to item 23, in which the signal frame is a frame signal orthogonal frequency division multiplexing (OFDM). 26. The method according to item 23, in which when generating the first synchronization sequence, the first synchronization sequence is formed, in which information indicating the second location of the second synchronization preamble is transmitted. 27. The method according to item 23, further comprising the step of generating a second synchronization preamble, wherein when generating the first synchronization preamble and the second synchronization preamble, control information is transmitted to at least one of the first synchronization preamble and the second synchronization preamble. 28. A method of receiving a signal frame in a wireless communication environment, comprising the steps of:
(a) receiving a wireless signal comprising a plurality of signal frames, each signal frame comprising a first synchronization preamble and a second synchronization preamble;
(b) identifying a first synchronization preamble in a particular signal frame;
(c) determining the location of the second synchronization preamble in this particular signal frame based, at least in part, on the information transmitted in the first synchronization preamble;
(d) receive the transmitted signal information from a combination of the first synchronization preamble and the second synchronization preamble. 29. The method of claim 28, wherein the signal frame is an orthogonal frequency division multiplexing (OFDM) signal frame. 30. The method of claim 28, wherein the information transmitted in the first synchronization preamble is carried by the first synchronization sequence. 31. A receiver for receiving a signal frame in a wireless communication environment, comprising:
(a) a receiving circuit for receiving a wireless signal comprising a plurality of signal frames, each signal frame comprising a first synchronization preamble and a second synchronization preamble;
(b) a control unit for:
(i) identifying a first synchronization preamble in a particular signal frame of a wireless signal,
(ii) identifying a second synchronization preamble in this particular signal frame based, at least in part, on information transmitted in the first synchronization preamble;
(iii) obtaining control information from at least one of a first synchronization preamble and a second synchronization preamble.

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