Abstract: A method synchronizes plural terminal communication systems and a counterpart communication station connected via a radio link within a multi-standard wireless communication system, wherein a counterpart transmission signal is transmitted from said counterpart communication station to the corresponding terminal communication system. A common reference clock signal is generated and supplied to a signal generation unit within said terminal communication system, wherein each terminal communication system comprises a conversion ratio unit having a conversion ratio. An accurate frequency datum is derived from each counterpart transmission signal in the terminal communication systems and a frequency control signal is determined from said accurate frequency datum.

Abstract: A central entity and/or a remote device in a communication system are designed to address the problem of maintaining upstream synchronization in the remote device after loss of the downstream signal. One issue of particular importance is maintaining upstream transmissions from the remote device in an S-CDMA (or perhaps S-TDMA) mode that do not degrade performance of the communication system via poor upstream timing or a need for re-ranging. By providing novel functionality at the central entity for synchronizing first and second downstream signals and/or by providing novel functionality at the remote device for determining a symbol clock offset between a first terminated downstream signal and a second re-acquired downstream signal, embodiments of the present invention facilitate maintenance of synchronization through the loss of the downstream signal, thereby minimizing the need for re-ranging and avoiding poorly timed upstream bursts.

Abstract: Methods and apparatus are disclosed to enable a fixed or a mobile ground based slave stations (VSAT: Very Small Aperture Terminal) in a communication network to receive TDM transmissions from and transmit TDMA burst transmissions to one or more ground-based gateway stations in a networking system that employs one or more geosynchronous satellites. Each gateway station transmits on one or more forward TDM channels to the slave stations; however, one primary gateway acts as the master station at any given time which transmits the network control messages to the slave stations (VSATs) that control their TDMA transmission behavior on the network.

Abstract: A base station includes a center frequency setting unit, a local oscillator, a baseband processor, and an RF processor. In the event of a frequency band change, the center frequency setting unit sets a center frequency of a use frequency channel to have a predetermined offset value with respect to a center frequency before the frequency band change. The local oscillator generates an LO frequency signal according to the center frequency set by the center frequency setting unit. The baseband processor generates a downlink baseband signal. The RF processor uses the LO frequency signal to convert the downlink baseband signal into an RF signal prior to transmission.

Abstract: A method for synchronizing overlapping cells covered by different base stations include obtaining a propagation delay between a first base station and a second base station, scheduling by the first base station a selected one of first users located in a first cell covered by the first base station to transmit a first data packet which is a part of a transmission data frame, transmitting at the selected one the first users a transmission offset indicating the difference in a time domain between the beginning of the transmission data frame and the first data packet, in response to the reception of the first data packet, recording a reception offset at a selected one of second users located in a second cell covered by the second base station, the reception offset indicating the difference in time domain between the beginning of a reception data frame and the first data packet, transmitting at the selected one of the second users the reception offset to the second base station, calculating at the second base stat

Abstract: A timing control system includes a counter that is initiated by a time accurate strobe (TAS) signal. A counter value is recorded when a message arrives in a buffer. A baseband integrated circuit (BBIC) calculates an integer number of counter periods and a fraction of a counter period corresponding to a timing correction value received from a base station. The BBIC issues a TAS signal during a counter period that occurs at the integer number of counter periods. At an expiration of the fraction of an ensuing counter period, the first one of a plurality of frame time slots is sent from the buffer to an antenna via a radio frequency integrated circuit (RFIC). The BBIC calculates, then stores in a memory, timing adjust values for the plurality of frame time slots so that each frame time slot can be time adjusted during message transmissions without an issuance of an additional TAS signal.

Abstract: A method of allocating control information in a wireless communication system is provided. The method includes: allocating essential control information of a first system to a first sub-frame in a frame including a plurality of sub-frames each of which comprises a plurality of orthogonal frequency-division multiplexing (OFDM) symbols; and allocating essential control information of a second system to an nth sub-frame in a fixed position from the first sub-frame (where n is an integer satisfying n>1). Accordingly, in a frame supporting heterogeneous systems, essential control information can be fixedly allocated to a specific position while maintaining the number of system switching points, at which switching occurs between the systems, to one even if a radio resource allocation amount changes between the systems, and thus the essential control information that must be received by all user equipments can be effectively provided without the increase of overhead.

Abstract: Method and apparatus are provided for estimating Time of Arrival (“TOA”). The method includes: performing channel estimation according to a Normal Burst (“NB”) free of interference and a local training sequence and generating a channel estimate, performing TOA estimation according to the channel estimate, and adjusting a synchronization position of the current NB according to a TOA estimation result. Interference to signals is cancelled before the TOA estimation, thus overcoming energy estimate deviation arising from interference in a strongly interfering radio environment, as occurs in the prior art, and preventing the impact on the TOA estimation. The disclosed methods and apparatus provide for more accurate energy estimates in a strongly interfering radio environment. The technical solution under the present invention does not require adjustment of the method of adjusting the search window.

Abstract: A method, apparatus, and system for time synchronization are disclosed. The method comprising: obtaining a master sending time stamp, a slave receiving time stamp, a slave sending time stamp, and a master receiving time stamp; and adjusting the time of the slave clock according to the offset calculated from the time stamps to synchronize with the clock time of the master clock. With the present invention, in passband transmission systems that transmit signals continuously in units of symbols, the time synchronization is implemented between the master clock and the slave clock.

Abstract: A method of and a system for synchronizing a plurality of spaced apart nodes of a network to a reference time of a control center, the method comprising receiving measurement data from each of the plurality of nodes; ranking the plurality of nodes with respect to one another according to the measurement data; selecting one or more master nodes from the plurality of nodes according to the ranking; assigning each of the plurality of nodes to a corresponding master node; determining a first time offset between the local time measured at each node and the local time measured at its corresponding master node and determining a second time offset between each of the master nodes and the reference time such that the time offset between the local time measured at each node and the reference time can be determined.

Abstract: A multi-carrier cellular wireless network (400) employs base stations (404) that transmit two different groups of pilot subcarriers: (1) cell-specific pilot subcarriers, which are used by a receiver to extract information unique to each individual cell (402), and (2) common pilots subcarriers, which are designed to possess a set of characteristics common to all the base stations (404) of the system. The design criteria and transmission formats of the cell-specific and common pilot subcarriers are specified to enable a receiver to perform different system functions. The methods and processes can be extended to other systems, such as those with multiple antennas in an individual sector and those where some subcarriers bear common network/system information.

Abstract: Systems and methods are provided for determining and applying timing corrections in a digital communications system. In an aspect, a timing correction method is provided for a multi-carrier system. This includes aligning two or more symbols with respect to each other from a symbol subset in order to account for timing differences between the symbols. The symbol alignment is first carried out to generate channel estimates for data demodulation. The channel estimates, thus generated, along with the timing alignment information are in turn used for determining timing corrections-to be applied to future symbols.

Abstract: A wireless communication system has transmission apparatus transmitting a wireless signal based on a transmission unit and reception apparatus. The reception apparatus includes plural reception devices receiving the wireless signal to obtain the informational signals and output-controlling device selecting any informational signal from the informational signals. The reception device has communication-quality-detecting device that detects communication quality of the wireless signal, a memory storing the informational signal, and synchronization-detection-storage-controlling device that detects the synchronization signal and controls the memory to store the informational signal based on a detected result of the synchronization signal.

Abstract: Techniques for performing time tracking in a communication system utilizing a cyclic prefix are described. In an aspect, a receiver may detect for large timing errors based on early and late received samples obtained with early and late FFT windows, respectively. The receiver may derive first and second channel impulse response (CIR) estimates based on the early and late received samples, respectively, determine an early channel energy based on the first CIR estimate, determine a late channel energy based on the second CIR estimate, compute an update amount based on the early and late channel energies, and update the FFT window position based on the update amount. In another aspect, the receiver may perform time tracking with an inner time tracking loop (TTL) and an outer TTL. The receiver may update the FFT window position in coarse steps with the outer TTL and in fine steps with the inner TTL.

Abstract: Disclosed are a wireless communication system, method, and site controller for mitigating at least one of a transmission timing synchronization loss and a receiving timing synchronization loss at a base station. The method includes determining, at a first base station, a loss of a timing reference the timing reference is used by the first base station for timing synchronization of at least one of a transmission and reception of wireless data. The timing synchronization is predefined and common between at least the first base station and a second base station. The method further includes adjusting, in response to the determining, at least one of a transmit guard time and a receive guard time by at least one symbol time.

Abstract: A method for multiplexing voice and data communication using a communications network is presented. In the method, at least one voice bit from a voice bit stream is retrieved, and at least one data bit from at least one data bit stream is retrieved. When the voice bit stream is not in a discontinuous transmission (DTX) period, the at least one voice bit and the at least one data bit are used to generate a modulated symbol. The method includes transmitting the modulated symbol using the communications network.

Abstract: A system and method for pre-scanning for a wireless channel selection is provided. The methodology is executed by a first fixed location wireless device to improve initial channel selection in a wireless network where a plurality of fixed location wireless devices is contemporaneously initialized. On a predetermined channel, there is a transmission of at least one message including an identifier of the first device. On the predetermined channel, there is a transmission of at least one message indicative of readiness to transition to a subsequent processing step. The methodology also commences scanning for channel selection purposes.

Abstract: Methods and systems for slow associated control channel signaling are disclosed. An example method for securing communications in a mobile network disclosed herein comprises transmitting a first variant of a message of a first type on a first slow associated control channel (SACCH) before ciphering is started on the first SACCH, and after ciphering is started on the first SACCH, transmitting a second variant of the message of the first type on the first SACCH, and subsequently transmitting the second variant of the message of the first type on the first SACCH, wherein the subsequently transmitted second variant of the message of the first type is the next transmitted message of the first type on the first SACCH.

Abstract: A data transmission and reception apparatus is used for a high efficiency satellite transmission. The apparatus includes an initial phase calculation unit to calculate initial phase information using a preamble and a postamble of a data packet applied thereto, a symbol transition calculation unit to perform forward and backward metric operations using the initial phase information calculated by the initial phase calculation unit and a pilot symbol in the data packet to calculate a symbol transition of the data packet, and a phase error estimation unit to calculating a phase error using the pilot symbol in a spot where the pilot symbol is positioned, the calculated phase error being provided to the symbol transition calculation unit.

Abstract: Magnetic field communication methods and apparatuses are performed by the coordinator and node of a magnetic field area network, respectively. The method which is performed by the coordinator includes: (a) sending a request packet requesting association with a network, disassociation from a network, network association state checking, data transmission, or group address setting, (b) receiving response packets, (c) selecting one or more response packets from among the received response packets, (d) sending a response acknowledgement packet to nodes corresponding to the selected response packets, (e) receiving response packets resent by nodes which have not received the sent response acknowledgement packet, (f) selecting one or more response packets from among the response packets received at (e), and (g) sending a response acknowledgement packet to nodes corresponding to the response packets selected at (f).

Abstract: A method of and an apparatus therefor searching a cell in a mobile station of a communication system in which a plurality of cells are grouped into a plurality of cell groups, and each cell group includes at least two cells. The method includes detecting a primary synchronization signal and a secondary synchronization signal from a received signal, and identifying a cell based on a combination of the primary synchronization signal and the secondary synchronization signal. The secondary synchronization signal is related to the cell group to which the mobile station belongs and the primary synchronization signal is related to the cell to which the mobile station belongs within the cell group.

Abstract: A transmitter transmits time synchronized data via a pager/WiMax/802.x access to a receiver system, wherein the receiver system is programmed to receive data for specific geographic locations. The geographic locations may be specified by the user or by the receiver system, and includes state, zip codes, towns, counties, towns, or cardinal regions. The receiver is able to find its location when outside its cell region and is able to synchronize to the data transmitted in the new cell region. Further, the receiver system is able to remotely monitor weather data and other information at a different location via wireless Internet or voice over IP. A transceiver may also be used to receive weather or alert data. In response to receiving data, the transceiver transmits the data to low powered devices in a house using a different frequency band than the frequency band it received the data.

Abstract: A wireless terminal using OFDM signaling supporting both terrestrial and satellite base station connectivity operates using conventional access probe signaling in a first mode of operation to establish a timing synchronized wireless link with a terrestrial base station. In a second mode of operation, used to establish a timing synchronized wireless link with a satellite base station, a slightly modified access protocol is employed. The round trip signaling time and timing ambiguity between a wireless terminal and a satellite base station is substantially greater than with a terrestrial base station. The modified access protocol uses coding of access probe signals to uniquely identify a superslot index within a beaconslot. The modified protocol uses multiple access probes with different timing offsets to further resolve timing ambiguity and allows the satellite base station access monitoring interval to remain small in duration.

Abstract: A method and a system for implementing hard handovers between access networks are provided, and the method includes: the access network on the target side obtaining the loop round trip delay of the pilot of the access network on the target side, and setting a center of a searching window of the pilot of the access network on the target side according to the obtained loop round trip delay of the pilot of the access network on the target side, so as to carry out the hard handovers between the access network on the source side and the access network on the target side. With the invention, the hard handovers between access networks could be implemented successfully.

Abstract: Provided is a radio communication method capable of optimally using the wide-band communication enabled time while maintaining power saving in an ad hoc network. According to this method, in the ad hoc network using the wide-band communication and a narrow-band communication, transmission and output of the narrow-band synchronization tone signal and the resynchronization tone signal are controlled so that the reach radius of the narrow-band synchronization signal and the resynchronization tone signal exceeds the reach radius of the wide-band signal (milli-wave UWB signal). Thus, when radio communication devices pass by each other, super frame synchronization is completed before reaching the wide-band communication enabled range of the ad hoc network, thereby optimally using the wide-band communication-enabled time.

Abstract: A method for transmitting data includes receiving at a first relay station first data from a parent station during a downlink period comprising a plurality of downlink zones. A network coding zone is one of the plurality of downlink zones and is located at an end of the downlink period, and the first data is received in at least one of the plurality of downlink zones other than the network coding zone. The method further includes receiving at the first relay station from a child station, second data during an uplink zone, and transmitting third data by the first relay station to the child station, during the network coding zone using a resource. The method further includes transmitting the third data to the parent station, during the network coding zone, using the resource. The third data results from the first data being effectively logically XOR-ed to the second data.

Abstract: A system and method of communicating signals is provided. The system includes a plurality of satellites, at least one receiver, and at least one satellite uplink station. The plurality of satellites include at least one active satellite. The at least one receiver is in communication with the plurality of satellites, and receives a signal from the at least one active satellite. The at least one satellite uplink station is in communication with the plurality of satellites, and transmits the signal and alters a frequency of the signal based upon a location of the at least one active satellite to reduce a Doppler frequency shift when activating and deactivating the plurality of satellites.

Abstract: There are provided measures for cell search and synchronization. Such measures may exemplarily comprise acquiring an observation signal for a carrier signal on a carrier which is under consideration for synchronization with a desired cellular system, calculating a power measure of the observation signal, which indicates a received power of said carrier signal, calculating a non-circularity measure of the observation signal, which indicates a non-circularity of said carrier signal, and calculating a ranking measure, which indicates an applicability of said carrier for synchronization with the desired cellular system, based on the calculated power measure and the calculated non-circularity measure.

Abstract: Using as a reference a known signal assigned to one of a plurality of streams that constitute a packet signal, a control unit applies a cyclic timing shift to known signals assigned to the other streams so as to produce packet signals which are to be transmitted finally. While varying the amount of timing shift, the control unit produces a plurality of packet signals and appends an identification number, with which to uniquely identify each of the plurality of produced packet signals, to each of the packet signals. A baseband processing unit and the like transmit, as a transmission rate inquiry signal, a packet signal constituted by a plurality of streams where the amounts of timing shift are made to differ, and receive a response signal to which the same identification number is appended for the inquiry signal.

Abstract: Embodiments herein provide a method and system for synchronization in a Wireless Communication Network using a new frame, Synchronization Frame (SF), and a configurable length of the same that is transmitted from a Network Controller (NC) to the Network Elements (NEs) in the network. The periodicity of the SF could be changed, to align with the data exchange periodicity, while still keeping synchronization. The length of the SF is made configurable to achieve this effect. It is directly proportional to the period, with which it needs to be transmitted, i.e., a larger delay between two SFs is achievable through the use of a larger SF frame size. This method provides a mechanism in which synchronization between the NC and NEs is achieved by listening to only a part of the SF, which is constant in size. This method also provides tolerance to failure by using acknowledgement schemes.

Abstract: A method for relaying and forwarding feedback information in hybrid automatic repeat request scenario is provided, wherein the method for sending feedback information includes that: a relay station receives a resource allocation message; the relay station determines the time of sending the feedback information according to the resource allocation message, and sends the corresponding feedback information when the feedback time arrives. The processes of triggering the relay station to perform feedback or sending in multiple HARQ scenarios such as initial transmission and retransmission of downlink and uplink, and uplink feedback loss of subordinate node etc. are integrally and uniformly defined according to the present invention.

Abstract: A method and apparatus for enabling multi-band transmission includes transmitting a beacon on a first radio band and transmitting the beacon on a second radio band. The beacon includes coordination information for transmission on the first and second radio bands.

Abstract: The present invention discloses a method and an apparatus for synchronization in a communication system, the method includes: detecting whether a user equipment is in an uplink out-of-synchronization state; triggering, by a downlink scheduling entity, an uplink enhanced random access synchronization process, if the user equipment is in the uplink out-of-synchronization state; and obtaining, by an uplink scheduling entity, a user equipment identifier sent by the user equipment on which the uplink enhanced random access synchronization process is triggered, and informing the downlink scheduling entity via an interaction with the downlink scheduling entity that uplink synchronization of the user equipment is restored.

Abstract: A method, performed by an access point of a cellular network, obtains time information by identifying a control channel cycle boundary; at a beginning of the control channel cycle boundary, sending a request to a time server; receiving a response from the time server, the request including a server time; and obtaining the timing information using the server time. Obtaining the timing information includes using the server time and a first reference time to obtain an integer and a fraction; using the fraction to obtain a time difference; and using the time difference to obtain the timing information.

Abstract: A communication system includes a synchronizing signal generator that generates a synchronizing signal based on a timing of an alternating waveform in a power line, a data communicating circuit that performs the data communication, and a communication controller that controls to acquire a transmitting right utilizing a timing of the synchronizing signal and to control the communication circuit in accordance with whether or not the communication apparatus acquires the transmitting right.

Abstract: The GCL sequence index of each cell/sector is assigned so that a difference of the indices between adjacent cells/sectors is more than N, where N?1. During GCL index detection, the adjacent N?1 indices of an index with the largest magnitude can be deleted from handoff candidate cell indices.

Abstract: A wireless communication system broadcasts a control signal at a first frequency band from a base station and allocates additional frequency band(s) for transmitting data via terminal(s). A control signal at the first frequency band indicates the location of the additional frequency band(s) and is not transmitted over the additional frequency band(s). Wireless data transmission is simultaneously performed over the first frequency band and the additional frequency band(s). Each terminal receives the control signal, which is used in time-synchronizing frames between the wireless data transmission at the first frequency band and the wireless data transmission at the additional frequency band(s). The control signal also includes control data for managing wireless data transmission between the base station and the terminal(s) at the first frequency band, and is utilized instead of a control signal at the additional frequency band(s).

Abstract: A method and system for reducing power consumption of OFDM (Orthogonal Frequency Division Multiplexing) signal synchronization circuit comprises a sync setting, a sync controller, a sync pipeline and a data corrector. The sync setting dynamically changes correlation data sample rate based on synchronization statuses and results. The sync controller controls and schedules frame and symbol synchronizations, and turns on and off the sync pipeline based on synchronization activities. The sync pipeline integrates frame and symbol synchronization operations, synchronizes receiving signal with scalable synchronization window, synchronization sequence length, synchronization delay and variable data sample rate. Data corrector adjusts input data with coarse timing and fine frequency offsets estimated in sync pipeline, and generates corrected output data for further processing. By using the above techniques, the power consumption of signal synchronization circuit is reduced.

Abstract: A transmitter apparatus at a base station transmits program information using a plurality of carriers with at least some of the carriers having different transmit power levels. The carrier associated with the highest transmit power level conveys broadcast information carrying basic program information. A carrier associated with a lower power level conveys broadcast information including enhancement information and/or additional content. The enhancement information and/or additional content may include a higher level of video and/or audio resolution, additional video and/or audio content, support for additional languages, a text stream, and/or advertisements. A wireless terminal tunes, receives and processes the broadcast information. A wireless terminal can recover different levels of resolution of a broadcast program, e.g., a digital video broadcast program, and/or different amounts of additional content, depending upon which carriers are being used.

Abstract: Systems and methods for handling automatic repeat request (ARQ) resets are described. A first device may receive a message initiating an ARQ reset procedure transmitted by a second device. The first device may determine if both the first and second devices have initiated an ARQ reset procedure. The first device may take action to limit a loss of blocks of data exchanged between the first and second devices, if both the first and second devices have initiated an ARQ reset procedure.

Abstract: The present invention is to provide a mobile communication terminal with a GPS function capable of further varying the positioning performance of each positioning mode preinstalled in the terminal. A GPS positioning section of the mobile communication terminal with the GPS function can perform positioning in a plurality of positioning modes using the A-GPS system. When a GPS control section of the mobile communication terminal with the GPS function causes the GPS positioning section to perform positioning, the GPS control section sets a positioning mode in the GPS positioning section, varies an allowable error of a communication synchronizing clock established between the terminal and a base station as a parameter relating to the positioning performance of GPS positioning based on the A-GPS system in which a fixed value has been conventionally used, and sets the allowable error in GPS positioning means.

Abstract: Various embodiments facilitate data communication between a client device and a remote device over a voice channel of a telephone system. In one embodiment, the data communication over the voice channel is synchronized to align with voice frames utilized by the telephone system to transmit communicated data between the devices. In some embodiments, the synchronization is performed by determining an offset between a received synchronization audio signal and the voice frames used by the telephone system to process the synchronization audio signal, such as based on an amount of energy present in the received synchronization audio signal.

Abstract: A congestion control system is provided between a terminal and a server device to avoid a congestion state in the server device by preferentially regulating the request with a high load on the server device. The congestion control system estimates the load of the request from the terminal to be placed on the server device for the next communication sequence, based on the response from the server device to the request from the terminal, and adds the estimated load information to the response to the terminal. Subsequently, the request from the terminal includes the load information, so that the congestion control system controls the regulation of the request from the terminal based on the load information included in the request.

Abstract: A cellular communication system comprises a network based radio bearer controller (123) which is arranged to control and manage the setup and operation of radio bearers. The radio bearer controller comprises a RAB processor (201) which is arranged to set up a plurality of user plane radio bearers for a user equipment (101). The plurality of user plane radio bearers all support a common service. The radio bearer controller (123) further comprises a link processor (203) which links the plurality of user plane radio bearers. The radio bearer controller (123) can process linked user plane radio bearers in relation to each other, for example by terminating all linked user plane radio bearers if a single radio bearer fails. The invention may be particularly suitable for a UMTS (Universal Mobile Telecommunication System) communication system supporting services using a plurality of UMTS user plane radio bearers.

Abstract: A wireless synchronization device is used to coordinate the timing and activities of individual, possibly physically separated, wireless service providers with defined coverage area. Further, the synchronization information is used to coordinate the timing and activities of portable wireless client devices in an autonomous, wireless proximity sensing and data transfer network. Moreover, one or more of the wireless service providers can be arranged to simultaneously monitor broadcasts from the wireless synchronization device and communicate with one or more of the portable wireless client devices.

Abstract: A method of polling in a wireless communications system includes prohibiting polling within a predetermined period and triggering a poll function while polling is prohibited. After the predetermined period has expired the method determines that there are no protocol data units (PDUs) scheduled for transmission or re-transmission and that the poll function was triggered by a “window-based” trigger, and selects a PDU to schedule for re-transmission to fulfill the poll function.

Abstract: Starting up and synchronizing multiple access points in a wireline communications circuit using transceivers compatible with a wireless communications protocol with an adaptive Time Division Multiple Access scheme for a multi-channel medium with colocated transceivers. Synchronization readiness is asserted and the access points wait for a synchronization start signal's assertion. Methods of operating an access point, its implementation as a chip are further disclosed. An access point assembly including the access points and a synchronization circuit are also disclosed.

Abstract: The present invention relates to a method of generating a downlink frame. The method of generating the downlink frame includes: generating a first short sequence and a second short sequence indicating cell group information; generating a first scrambling sequence and a second scrambling sequence determined by the primary synchronization signal; generating a third scrambling sequence determined by a short sequence group-a wireless communication system uses a plurality of short sequences and the plurality of short sequences are grouped into a plurality of short sequence group-to which the first short sequence is assigned; scrambling the first short sequence with the first scrambling sequence and scrambling the second short sequence with the second scrambling sequence and the third scrambling sequence; and mapping the secondary synchronization signal that includes the scrambled first short sequence and the scrambled second short sequence to a frequency domain.

Abstract: The present invention relates to a method for generating a downlink frame includes: generating a first short sequence and a second short sequence indicating cell group information; generating a first scrambling sequence determined by a first synchronization signal; generating a second scrambling sequence determined by a group to which the first short sequence belongs, the wireless communication system using a plurality of short sequences and the plurality of short sequence being divided into a plurality of groups; scrambling the first short sequence with the first scrambling sequence; scrambling the second short sequence with at least the second scrambling sequence; and mapping a second synchronization signal including the scrambled first short sequence and the scrambled second short sequence in the frequency domain.

Abstract: A communications system network that enables secondary use of spectrum on a non-interference basis is disclosed. Each secondary transceiver measures the background spectrum. The system uses a modulation method to measure the background signals that eliminates self-generated interference and also identifies the secondary signal to all primary users via on/off amplitude modulation, allowing easy resolution of interference claims. The system uses high-processing gain probe waveforms that enable propagation measurements to be made with minimal interference to the primary users. The system measures background signals and identifies the types of nearby receivers and modifies the local frequency assignments to minimize interference caused by a secondary system due to non-linear mixing interference and interference caused by out-of-band transmitted signals (phase noise, harmonics, and spurs).