Access channel with limited reception time

FIELD: physics; communications.

SUBSTANCE: method consists of the following stages: reception of request for channel access from user terminal. Reception of the user terminal can be one of several active user terminals. The transmission cycle duration is determined as a result of reception of a request for channel access. The arrival time of data to the cycle is determined for the user terminal. The arrival time of data to the user terminal is set, so as to designate the channel for the user terminal, starting from the time of arrival of data.

EFFECT: reduced probability of collisions during transfer of data from different users.

31 cl, 8 dwg

This patent application claims the priority of provisional application No. 60/551689, entitled "CDMA-ALOHA RANDOM ACCESS CHANNEL WITH CONSTRAINED ARRIVAL TIMES", registered on March 9, 2004 and assigned to the holder of the present invention and it is explicitly incorporated herein by reference.

The technical field

The invention relates to the field of electronic communication, more specifically, to the field of configuration access channels, and pairing them in communication systems.

Description of the prior art

In the last decade, many cellular standards chose interfaces physical layer multiple access orthogonal and non-orthogonal code division multiplexing (CDMA).

In the context of data transmission according to the principle "from many points into a single point, where multiple users are trying to send information to a Central receiver, can be used non-orthogonal CDMA. Reverse lines of communication standards, cdma2000 and WCDMA are good examples of such use.

A fundamental characteristic of the channel-orthogonal CDMA is that it is limited in respect of interference relative to itself. The deterioration of the communication between the user and the Central receiver is mainly due to other system users, which at the same time the OS is effect the access to the channel in the same frequency range. Each parallel transmitter distinguishable only by code that it uses. In addition, in order for the system to work, the energy that is present in the environment due to the transmission of other users, should have almost the same statistical properties as white noise. This is a coincidence, which allows different users to successfully transmit information at the same time in the same frequency range, while the number of concurrent users does not exceed a certain maximum N. Typically, the Central object assigns each user a different transmission code. Special properties of these codes ensure the required characteristics of mutual interference.

On-line CDMA channel, such as reverse link cdma2000, the actual number of users U that are present in the system, has the same order of magnitude as the number N maximum concurrent users for a successful transmission. This focused on the connection configuration is well suited for applications such as speech transmission, sustainable needs of traffic. For example, a typical speech coder generates 192 bits every 20 milliseconds. In addition, the transmission of frames is implemented in such a way that, as soon as the receiver detects a specific user, he knows exactly when to expect the next is the information frame. Conceptually, the receiver is composed of U parallel receivers, each acting in one of the codes. For a typical cdma2000 - realization of U is approximately equal to 60, which may be implemented in the receiver relatively low complexity.

For another type of user traffic, such as viewing a Web page, using the channel of each user is much more sporadic, so the total number of users U that the system can efficiently support is far greater than the allowable number of simultaneous transmissions N. Offers some systems, where N˜30 and U˜15000. In addition, the sparse nature of the traffic offers non-connection access Protocol type Aloha. In based on Aloha channel access each user accesses the channel whenever the user has data to transmit. If many users try to simultaneously access the space of the same channel, there can be a collision and both programs can be successful.

In based on Aloha channel access time of arrival information frames is unknown at the receiver with a probability distribution that is uniform in time. This adds an extra dimension (time of arrival) to the complexity of the demodulator, so it is to each possible transmission code must be continuously checked for packet arrival. Almost is much more difficult to demodulate the signal transmitted using the specified code when the signal is unknown. Individual demodulators, which are necessary for channel CDMA-Aloha, have orders of magnitude more complex than the rules mentioned above for connection-based protocols.

Is in principle undesirable, based on the complexity of the receiver to assign 15000 different codes and have 15000 parallel demodulators. One possible approach is to use a smaller set of codes C < U, from which users randomly select one code every time they want to start the transfer. Limiting the number of access codes increases the collision probability.

Although allowable simultaneous transmission of two different transmitter using the same code that comes in the receiver at the same time will not interfere randomly with each other. The mixture of informative characters with the same code at the same time and in the same frequency range most likely to cause the loss of both packets. This problem can be solved by using a sufficiently large code set C, such that collisions are unlikely. However, increasing the number of available codes C the complexity of the receiver increases.

It is desirable to have the config of the radio channel access Protocol in the communication system, which allow many non-permanent active users while reducing the probability of collisions for transmissions from different users and maintaining or reducing the complexity of the receiver.

The invention

Proposed systems, methods and apparatus for configuring and accessing the random access channel in a CDMA communication system. The number of users supported by the random access channel can be optimized by assigning different time of arrival for each of the multiple users. Different arrival times for different users can be on the order of a single elementary signal.

Each of the users can be synchronized in time and can transmit data at a time, which compensates for the propagation delay to ensure the possibility of arrival of the data in the receiver of the destination at the appointed time. In the CDMA system, each user can transmit data, which is expanded using the same code extensions, provided that vzaimokreditovanie properties code is sufficient to identify the source, which is shifted in time with respect to another user. Alternatively, users may be assigned a code from the specified list is and the code sequences. The arrival time may be determined based on the number of active users and may be appointed for each transmission of each user.

A receiver configured to receive time-bound transmissions from multiple users, can reduce the search space for each of the set of active users to a specified code expansion and the given time window corresponding to the user. The scheduled arrival time reduce the complexity of the receiver, allowing the system to support more users than can be supported by the channel random access, which uses unlimited access to the channel, such as Aloha.

Also the claimed method of distribution channel access, which includes the determination of the cycle time of the transmission, determining the time of arrival in the cycle of transmission to destination user terminals from the set of active user terminals and the transmission time of arrival of the user terminal to select channel user terminals, since the time of arrival.

Also the claimed method of the destination channel access, including receiving a request for access to the channel from the user terminal, the synchronization of the time base with the user terminal, determining the transmission cycle having a duration of the guard proportional to the duration of elementary CDMA signal, determining the time of arrival, coinciding with the boundary of the elementary signals in the cycle of transmission, and the transmission time of arrival of the user terminal to select channel user terminals, since the time of arrival.

Also the claimed method of data transmission in the channel, which includes the access request to the channel, the reception destination time of arrival in response to the request and transmission of the data block with an offset in time relative to the time of arrival so that the initial part of the block of data arrives at the receiver at the appointed time.

Also the claimed method of receiving data in the channel, which includes determining the time of arrival in the cycle of transmission assigned to the user terminal, receiving from the set of active user terminal, the search time window, which includes the arrival time for the transmission from the user terminal, and receiving a block of data from the user terminal.

Also claimed the device to work in a limited time joining the channel. The device includes a data buffer configured to store a data block, a data modulator coupled to the data buffer. The data modulator made with the possibility of extension data in the data block via direct is odulele sequence, using code for generating modulated data. The device also includes a transmitter intended for receiving modulated data from the modulator data and selectively transmitting the modulated data, and the temporary module transmission control connected to the transmitter and intended for receiving the destination time of arrival and the control transmitter for transmitting the modulated data with a time shift in relation to the appointment time of arrival so that the transferred data is initially received in the receiver, essentially, according to the appointment time to come.

Also claimed the device to work in a limited time joining the channel. The device includes a module transmission cycle, designed to determine the cycle time of the transmission, the module boundaries of time, designed to determine the time of arrival in the cycle of transmission assigned to the user terminal, and the receiver is designed to receive multiple transmissions from multiple user terminals and to search for multiple transmissions in a time window that covers the arrival time for the transmission from the user terminal.

Brief description of drawings

The features, objectives and advantages of embodiments of the invention are explained in the following detailed description of the research Institute, with reference to the drawings, in which identical elements have the same reference position.

Figure 1 - functional block diagram of a variant of implementation of the wireless communication system that implements time-limited channel access according to the invention.

Figa-2B - time diagrams of embodiments of channel random access Aloha and time-limited access channel according to one variant embodiment of the invention.

Figure 3 - functional block diagram of one possible implementation of a base station, configured to control time-limited channel access according to the invention.

4 is a functional block diagram of a user terminal, configured to mate with limited time access channel according to the invention.

5 is a block diagram of a sequence variant of the process of the destination channel.

6 is a block diagram of the operational sequence of a variant of implementation of the process in a limited time joining the channel.

7 is a block diagram of a sequence variant of the process receiving the signal from the limited time of arrival of the channel.

Detailed description of the invention

Wireless communication system having a channel with limited access times etc is running, disclosed as a device designed for operation in channel access, and ways of interacting with channel access. The wireless communication system may implement an access channel, in which the time of arrival of a transmission from a particular user terminal is limited to a specified time.

The arrival time can be selected from the set defined boundaries of the time of arrival and can be determined partially on the basis of the number of active users in the channel. For example, the communication system may designate the time of arrival of a specific user terminal modulo the number of active users in the channel. In another embodiment, the communication system may designate the time of arrival of a specific user terminal modulo some given number. In other embodiments, implementation of the communication system can also randomize the arrival time assigned to each user. Randomization can be performed for each transmission or on the basis of a certain number of transmissions or the time period. The communication system can transmit the arrival time corresponding to a specific user before each interval or at some other interval, which may be based on the manner in which the communication system determines the time of arrival.

The user terminal may first ASU is estolate contact with the base station to establish an active session on the channel through data transmission through the channel service information, which may be configured as a random access channel. The user terminal can access the channel service information a limited number of times during an active communication session, such as, for example, the initial establishment and the end of the session. The random access channel may cover the same frequency range as limited by the time of arrival of the canal. However, the user terminal is usually not synchronized with the base station to establish contact with it. Alternatively, the random access channel may be in a frequency range that overlaps with or is different from the frequency band limited by the time of arrival of the channel. As the user terminal transmits data in a relatively small number of times channel insider information, can be a low probability of collisions with transmission from another user terminal. The user terminal can synchronize the time base system and to establish an active communication channel for control information, and it may be time for a transmission for a limited time channel.

Limiting the time of arrival of the user transmission simplifies the configuration of the receiver. In each period of time of arrival, the receiver has is the information about what user terminal from a limited number of active user terminals assigned to this period of time of arrival. The receiver can be configured to search in a given time window and find the associated code for CDMA systems. The number of codes can be reduced significantly compared to the number of codes required for non-orthogonal channel random access CDMA, and can be reduced to a single code for all users.

Figure 1 shows the functional block diagram of a variant of implementation of the system 100 for wireless communication, implementing time-limited channel access. The system 100 includes one or more fixed elements that can communicate with one or more user terminals 110a-110n. User terminal, for example 110a may be configured to work with various communication protocols in a straight line and the return line. A direct line of communication refers to the communication line from the base station 120b to the user terminal 110a. The reverse link refers to the communication line from the user terminal, for example 110a, to the base station 120b. User terminal 110 may be a portable module mobile module or stationary module. User terminal 110 may also upominalsja mobile station, mobile device, mobile terminal, user equipment, a portable device, phone, etc.

Although the wireless communication system 100 shows only two user terminal 110a-110n, the wireless communication system 100 may be configured to support a first number N of simultaneous transmissions and the second number U active users who sporadically perform transmission to the base station 120b. For the sake of clarity the following description refers to a specific user terminal 110a. It is clear that the description is equally applicable to all user terminals 110a-110n coverage area of a system 100 for wireless communication.

In one embodiment, the user terminal 110a communicates directly with one or more base stations 120b, although only one is depicted in figure 1. In this embodiment, the base station 120b is shown as a cellular tower divided into sectors. The user terminal 110a will typically communicate with the base station 120b, which provides the highest signal level in the receiver in the user terminal 110a.

In another embodiment, the user terminal 110a communicates, through a ground station, a satellite 120a. The ground station may be internal to polzovateley the th terminal 110a or may be external (not shown) for the user terminal. Satellite 120a communicates with the base station 120b, usually indicated as a ground station or gateway. The user terminal 110a transmits a signal return line connection to the satellite 120a via the ground station and the satellite 120a relays the signal return line connection to the base station 120b. The base station 120b may be configured to send a signal direct line of communication to the satellite 120a, and satellite 120a may be configured to relay the signal direct line of communication to the user terminal 110a.

The base station 120b, regardless, does it link directly with the user terminals 110a-110n or via satellite 120a may be connected to the controller 140 of the base station (BSC), which routes the communication signals to the corresponding base station 120b and from it. BSC 140 is connected to the center 150 of the mobile communication switching (MSC), which may be configured to work as an interface between the user terminal 110a and the public switched telephone network 160 (PSTN) or some other network, which may be a packet data network 170. In one embodiment, packet network 170 may be a wide area network (WAN)such as the Internet. Therefore, the MSC 150 may also be connected to the PSTN 160 and packet network 170. MSC 150 may also be configured to coordinate m is sistemnoi transmission service with other communication systems.

The wireless communication system 100 may be configured to implement a channel having a limited time joining the back line, because of the structure of the reverse link, where each of the multiple user terminals 110a-110n may have an active session with the same base station 120b.

The user terminal 110a first communicates with the wireless communication system 100 and requests access to the channel with limited times of access. The user terminal 110a may first communicate with the base station 120b through the service channel random access. Service random access channel may be in the same or in other frequency ranges, relative to the range bounded by the time of arrival of the channel. The wireless communication system 100 may implement a Protocol such as Aloha Protocol for service random access channel. On figa presents the timing diagram 200 channel random access Aloha showing transmission from three different user terminals attempting to communicate with the base station. In the example on figa for the first user terminal, there are two collisions 202a and 202b before implementing a successful transmission. Similarly, for the second user terminal are two collisions 204a and 204b to realisatie the successful transmission. Also for the third user terminal, there are two collisions 206a and 206b before implementing a successful transmission. It is clear that the number of collisions for any user terminal is not limited to two.

Although figa shows that for each terminal are collisions and unsuccessful attempts to access the channel, the random nature of the transmission on the random access channel can substantially reduce the probability of collisions. The random access channel may be desirable for the initial installation as user terminals 110a-110n may be asynchronous with the wireless communication system 100 and may not be able to send a request in the specified time.

The user terminal 110a can also be synchronized with the wireless communication system 100 after the request for establishment of a session is active on a channel with limited time access. The user terminal 110a can be synchronized with the wireless communication system 100 using any synchronization method. For example, the user terminal 110a can be synchronized with the wireless communication system 100 in accordance with the methods described in patent application U.S. No. 10/428953 entitled ORTHOGONAL CODE DIVISION MULTIPLE ACCESS ON the RETURN LINK OF SATELLITE LINKS, registered may 1, 2003, assigned propriam the ku of the present application and fully incorporated into the present description.

As soon as the user terminal 110a is synchronized with the wireless communication system 100, the wireless communication system may determine the time of arrival of data sent by user terminal 110a, and may appoint the arrival time of the user terminal 110a. The wireless communication system 100 may transmit the destination time of arrival of the user terminals 110a, for example, using channel a straight line.

The wireless communication system 100 may be configured to assign an active user terminals, for example 110a and 110n, different arrival times instead of different codes. Thus, the wireless communication system 100 may be configured to assign U different times of arrival of each of the U different user terminals. The wireless communication system 100 may be configured to assign a time period to the time of arrival, which is selected from a set of equally spaced temporal boundaries. Alternatively, the time period for the time of arrival can be posted irregular manner or may be determined randomly.

In one embodiment, the transmission from the specific user terminal 110a-based CDMA system may arrive at the base station 120b, since any elementary signal in the i-th position modulo U. in Other words, the mi, each user terminal 110a-110n (u) can be configured to transfer received in the receiver at the time corresponding to each border of the b_uelementary signal from the set:

buu + kU k{0, 1, 2...}

(1)

Possible and/or desirable various changes of this variant implementation, and the actual implementation may be determined on the basis of a compromise of the requirements for the system development. For example, the wireless communication system 100 may assign the arrival times, which are determined modulo the number of active user terminals 110a-110n. Alternatively, the wireless communication system 100 may assign the arrival times modulo a given constant number. If the number of active users exceeds the defined constant module, the wireless communication system can implement a prioritization scheme to ensure the appointment time coming eventually to all user terminals.

In one embodiment, the wireless communication system 100 may be configured to determine and assign arrival times, so that the transmission of any two users at the same time not received at the receiver. In this variant the implementation of the entire set of user terminals 110a-110n can be effectively applied only code provided what this code is pseudo-random properties, when determining cross-correlation with shifted versions of itself. Codes with these properties can be obtained by using a shift register with linear feedback (LFSR). With this method of transmission the probability of collisions are effectively reduced to zero.

In the embodiment where one code is used for the whole population 110a-110n user terminal, the receiver in the base station 120b becomes simpler, because the code is known. Moreover, the points in time when the receiver must search for transmission to a particular user, are now discrete set of hypotheses, which also reduces the complexity in this aspect.

An implementation option to limit the time of arrival introduces a delay for the channel, which may not appear in pure scheme CDMA-Aloha, where the terminal transfer, in its discretion. This delay is determined by the transmission cycle, which can be determined intervals in the elementary signals between two successive times of arrival of the transmission user. In one of the embodiments described above, in each cycle of the U of elementary signals, each user terminal receives one opportunity to transmit, and thus, the delay experienced by a single packet is a uniform random variable with parameter U.

Note that even for large values of U˜15000 introduced delay is of the order of a few milliseconds, when the repetition rate of the elementary signal is of the order of several million (megachips) elementary signals per second. Some digital communication systems, such as systems using geostationary satellites, have internal delay distribution of the order of hundreds of milliseconds, even without considering the additional delays that may enter the communication line between the end points, for example, from the routers to the Internet. The percentage increase in delay in implementation is limited by the time of arrival of access in such systems is very small.

On FIGU - presents the timing diagram 210 of the example is limited by the time of arrival of the channel. Timing diagram 210 of figv shows three active user terminal, and each transmits a block of data in a limited time. The first user terminal transmits the data blocks 222a-222c, which come at the appointed arrival time, assigned to the first user terminal. Although only shows three transmission of data blocks 222a-222c, it is clear that the user terminal can continue to send data blocks arriving at the appointed time, until, when the user terminal N. the release channel. The time between successive transmissions, t_cis the transmission cycle. In the example on FIGU time period assigned to the first user terminal is the same in each cycle of transmission. Cycle 230 transmission, shown in the example on FIGU has a duration greater than that required to cycle through all of the transmitting user terminal. If the cycle 230 transfer is a multiple of the minimum increment of time, i.e. t_c=D×t_bthen the scheduled time of arrival can be defined as the appointment time by module D. Additionally, although figv shows that the length of the data block, for example 222a, less than the duration of the cycle 230 transmission, the duration of the block 222a data may exceed the duration of the transmission cycle. In this situation, the receiver may not require a search of the transmission from the user terminal at the appointed time, as it already receives transmission from the user terminal. Additionally, the system may not be expected to pass a new appointment period of time of the user terminal, if the length of the data block exceeds the duration of the transmission cycle.

Similarly, the second user terminal transmits blocks 224a-224c data that arrive at the appointed arrival time, oznaczenie the second user terminal, the length of each data block may be shorter or longer than the duration of the transmission cycle. Similarly, the period of time assigned to the second user terminal is the same in each cycle of transmission.

The third user terminal transmits blocks 226a-226b data that arrive at the scheduled arrival time assigned to the third user terminal. The period of time assigned to the third user terminal is the same in each cycle of transmission. However, the third user terminal has no data to transmit in the second cycle, transmission, and thus, no data is available for reception at the base station.

Increment 240 time t_bbetween successive assignments period of time may be fixed or may be variable. The minimum increment 240 time can be determined on the basis of the level of synchronization and configuration of the user terminal.

For example, in a wireless communication system, in which user terminals are stationary, and no significant multipath components of the signal are not present in the base station, the minimum increment of time may be relatively small. For example, the minimum increment 240 time may be the duration of the nogo elementary CDMA signal, 2 elementary signals, 3 elementary signals, 4 elementary signals, 5 elementary signals, 10 elementary signals and the like, or some other increment of time.

In other embodiments, the implementation of user terminals can be mobile or portable or base station can receive significant multipath components of the signal. In this embodiment, the minimum increment of time may be greater to significant multipath components from the first user terminal could come before the scheduled time of arrival for the second user terminal.

In the embodiment described above, where the arrival time for each user is always one and the same number of elementary signal modulo D, there is a possibility of occurrence of adverse events. Can analytically show that the blocks of data that begin in different periods of time, may have persistently different levels of interference. For example, in the example timing diagram for figv significant part of the transmission data block from the third user terminal, for example 226a, does not feel the influence of any other sources of interference from other user terminals. The overall consequence is a decrease in system throughput. One solution to this problem on the I wireless communication system is to each user terminal to assign a time period that is changed in each cycle of transfer, or the number D of elementary signals. Continuous rearrangement leads to a more uniform distribution of interference periods of time. The process of designating periods of time may be random, pseudo-random or may follow a specified sequence or algorithm.

In the channel CDMA-Aloha receiver in the base station has no information about what the user terminal transmits. Usually, the identification information of the sender is revealed only after the information frame has been properly decoded. In one embodiment, where the user terminal sporadically carried out only broadcast transmission, the base station is unable to determine who was the sender when there is a decoding error. In the limited time of arrival of the configuration of the receiver in the base station is known, what the user terminal transmits a block of data. If there is a decoding error, such information may be used, for example, to update loop power control for each user or to inform a specific user that was packet loss. the hildren CDMA typically use the control in a closed loop transmit power of the user terminal. The wireless communication system can use the loop power control for issuing commands to the transmitter of the user terminal to increase its transmit power if its transmitted data has not been correctly taken.

Figure 3 shows the functional block diagram of a variant of implementation of the user terminal 110 configured to work in a limited time joining the channel. User terminal 110 may be, for example, one of the user terminals 110a or 110n, shown in the embodiment of figure 1. For clarity shown and described only those parts of the user terminal 110 that are relevant to the present invention.

The user terminal 110 includes a receiver 302, intended for receiving a direct line of communication from one or more base stations. As described above for figure 1, the receiver 302 may receive transfer direct line of communication transmitted by the base station, or capable of receiving a direct line of communication, which are relayed by an intermediate element, such as a satellite. The receiver 302 may be configured to receive data and commands from the wireless communication system. The command and associated data may be transmitted using the service channel and may include parameters relating the Xia to the appointment time period for a limited time joining the channel. Other user data can be transmitted over the channel traffic. Alternatively, some or all of the data and control commands can be transmitted on the traffic channels of direct communication lines.

The receiver 302 may send commands and data received through official channels to the appropriate modules. The output of the receiver 302 may be connected to, for example, the module 310 synchronization module 320 time transmission and module 330 power control.

Module 310 synchronization is configured to synchronize the temporary support of the user terminal 110 with the time base of the wireless communication system. Module 310 synchronization can be configured with other modules of the user terminal 110, for example, to implement the synchronization methods described in patent application U.S. No. 10/428953. Module 310 synchronization can be configured to achieve the specified accuracy of the synchronization, which can be equal to or better than one elementary CDMA signal.

Module 320 transmission time can be configured to receive destination period of time and control by the transmitting tract in the user terminal to send a block of data at a time corresponding to reception of the data block in the base station at the appointed time. In one embodiment, the module 320 time transfer prinimaetsea period of time before each transmission cycle. In another embodiment, the module 320 transmission time can make the initial appointment period of time and can determine the future destination of the period of time is partly based on a specified algorithm. The predetermined algorithm may include pseudorandomization assignments period of time. In this embodiment, the base station determines similarly assignment period of time, using complementary algorithm. In other embodiments, the implementation module 320 transmission time can be configured to receive assignments period of time with less frequent intervals. The frequency can be periodic, for example once every specified number of cycles of transmission, or may be based on events. An example based on the events of the appointment period of time is reassigning periods of time, which coincides with the change in the number of active user terminals accessing the channel.

Randomization or permutation assignments periods of time can be determined in the base station and transmitted to the user terminal 110 or may be determined by module 320 transmission time, especially if the appointment time is a pseudo-random or deterministic.

Module 320 transmission time can take two types is their basic signal and the module and can identify the purpose of period of time in conjunction with module 310 synchronization. In other embodiments, the implementation module transmission time may accept the appointment period of time and can use the time offset specified by the synchronization module, which must be transmitted to the data block to be received in the base station within the assigned period of time. In other embodiments, the implementation module 320 transmission time can take other types of information time.

Module 330 power control can be configured to issue commands to the transmitter 350, and, more specifically, the amplifier 352 power transmitter 350, to increase or decrease the transmit power, partly on the basis of the control signal power, adopted in the transmission of data to a straight line.

The transmit path of the user terminal 110 may include a buffer data 340, which is configured to store data that must be transmitted to the base station. The data may include management and service signalling and traffic that must be transmitted on the reverse link, and can come from one or more sources (not shown). User terminal 110 retrieves the data block from the buffer 340 data and transmits the data block to the modulator 342 data. The data block may be chosen from a given set of dimensions of the data block, or he can decide on the size based on the volume of the data, which the user terminal 110 wishes to send, or can be a combination of the specified block size based on the amount of data that must be transmitted.

Modulator 342 data can be configured to modulate the data contained in the extracted data block. Modulator 342 data can be configured, for example, to extend bits of serial data by direct modulation of a given code sequence. Modulator 342 data can use the code generated by the LFSR in the modulator 342 data or can choose a code from a specified number of codes that are stored or generated in the user terminal 110. Modulator 342 data can be controlled to use a specific code based on the command or control signal received from the base station receiver 302.

The modulated data are fed to the transmitter 350, which transmits the signal in time, which is determined based on the offset time, which compensates for the propagation delay. The block of modulated data, thus, is configured for joining to the base station at the appointed time.

The processor 360 in conjunction with the processor commands stored in the corresponding memory 362 may be configured to implement part or all of one Il is more of the modules of the user terminal. For example, some or all of the functions of the module 320 transmission time can be stored in the memory 362 as software that is executed by the processor 360.

Figure 4 shows a functional block diagram of a variant of implementation, base station 120, which may be a base station of a wireless communication system, shown in figure 1. For clarity shown and described only those parts of the base station 120 that are relevant to the present invention.

Base station 120 may include a module 402 analog receiver that is configured to receive signals transmitted on the random access channel to establish an active session in a limited time joining the channel. The module 402 of the analog receiver can also be configured to receive signals transmitted for a limited time joining the channel. Module output signal 402 of the analog receiver can be converted into a digital signal for further processing.

The base station may include a multi-tap receiver connected to the output module 402 analog receiver. Multi-tap receiver may include block 410 search, which is designed, for example, to search for the most powerful of potentially multiple multipath signals coming from a specific custom t is rminal. Block 410 search may appoint the first multipath signal to the first outlet 412 and may assign a second multipath signal to the second outlet 414. Although shown only two outlet 412 and 414, tap the receiver may be implemented with any number of taps. Block 410 search can provide a search for transfer from the user terminal depending on bronirovania. Since each user terminal in a limited time joining the channel is assigned a time period for ward block 410 search can be configured to search for transfer from the corresponding user terminal in a time window that covers the scheduled time. Therefore, for each time block 410 search has information about the user terminal assigned to this period of time.

Each outlet 412 and 414 demodulates the assigned multipath signal, for example, by compression of the signal, using the appropriate code. The output signals of different outlets 412 and 414 can be enjoyed on a combiner 420, where multipath signals are aligned in time and coherently summed. In the variants of implementation, where multipath signals are largely absent, as, for example, where the stationary user terminal transfer on sat covoy relay station, multi-tap receiver having multiple outlets 412 and 414, and the corresponding multiplexer 420 can be omitted. Instead, you may use a single receiver path, equivalent to a single branch, which performs the search and demodulation.

The output signal of the multiplexer 420 may be connected to the processor 430 of the base strip. The processor 430 of the base strip may submit relevant part of the data in the base station controller (not shown). Additionally, the processor 430 of the base strip may apply control signals and auxiliary signals to the respective control modules.

A control module may include a module 440 of the transmission cycle, designed to determine the duration of the transmission cycle. Module 440 transmission cycle may determine a transmission cycle, for example, based on the number of active user terminal that communicates with the base station 120.

The control modules can also include a module 450 boundaries of time, which may be configured to determine the period of time that represents the arrival time assigned to a particular user terminal. Module 450 boundaries of time may also be configured to perform randomization or permutation periods of time that is used to more evenly distribute the impact p the fur on all user terminals. Module 450 boundaries of time can be configured to send assignments periods of time the processor 470, the processor 430 of the base strip and the block 410 of the search.

A control module may include a module 460 power control, which forms part of the control circuit power. Module 460 power control may determine whether the transmission power for a particular user of the terminal may be increased or decreased. For example, the processor 430 of the base strip may determine whether the data is skewed, adopted in accordance with the time of arrival, assigned to a specific user terminal. Base station 120 may then send a message requesting retransmission of the data. Additionally, the processor 430 of the base strip may report the inability to recover data module 460 power control, so that the module 460 power control may generate a control message for the user terminal, requesting from the user terminal to increase its transmit power. This loop power control is impossible in the random access channel, such as channel Aloha, as the receiver has no information about which user terminals attempt to transmit data, and cannot determine which user terminals are what initiatorname transmission, if collisions lead to loss or distortion of data. The processor 430 of the base strip may also determine that the received data corresponding to the specific user terminal, were accepted without errors. The processor 430 of the base strip can convey information about the error-free reception module 460 power control module 460 power control may generate a control message for the user terminal, requesting from the user terminal to decrease its transmit power. Module 460 power control may determine the message power control, partly based on the quality metrics of the received signal, such as frequency of occurrence of erroneous data, the bit error rate or frequency of occurrence of erroneous symbols. The output signals of the module 460 power control, and output signals of module 440 of the transmission cycle and module 450 boundaries of time can be fed to a modulator 482.

Modulator 482 is also associated with the buffer 480 data, which is used to store data that must be transmitted to each user terminal through the channels of direct communication line. Modulator 482 can modulate each of the signals a straight line using the appropriate code and can generate service signals of the output signals of one or more which of odula control.

The modulated signal is fed to the transmitter 490, providing a direct signal connection lines for different user terminals. The processor 470 in conjunction with the processor commands stored in the corresponding memory 472 may be configured to implement parts or all of one or more modules of the base station 120.

Figure 5 presents a flowchart of the sequence of operations variant of the method 500 assigning a limited time of arrival of the channel. The method 500 may be implemented, for example, the base station shown in figure 1 or figure 4.

The method 500 begins at step 502, when the base station receives the request from the user terminal to access the channel. The base station can accept a request from a user terminal, for example, random access CDMA Aloha, which is available for the service signaling and communication. The request initiates an active session for a limited time joining the channel.

The base station proceeds to step 510 and synchronizes the user's terminal so that the user terminal and the base station are synchronized with respect to the same temporal basis. In one embodiment, the user terminal is synchronized with the time the support base station with exactly what thew best, than one elementary CDMA signal.

The base station then proceeds to step 520 and determines the transmission cycle for a limited time joining the channel. As described previously, the transmission cycle is the duration between two successive times of arrival of a transmission to a specific user terminal. As described previously, the transmission cycle may be determined based on the number of active user terminals, or may be independent of the number of active user terminals. In one embodiment, the number of time periods, or time of arrival is equal to the number of active user terminals, and thus, the transmission cycle is equal to the minimum increment of time, multiplied by the number of active users. In other embodiments, implementation of the transmission cycle may be of fixed duration. Other options for implementation may use some combination of methods. For example, the length of time can be based on the number of active user terminals, but can be further restricted to be equal to at least a given minimum duration of the transmission cycle.

The base station then proceeds to step 522 and determines the arrival time for the destination user is defined to the terminal. The arrival time assigned to a specific user terminal, may be determined partly on the basis of arrival times assigned to other user terminals. The arrival times can vary on the duration of a single elementary CDMA signal or the multiple number of elementary signals. In one embodiment, the base station may assign a user terminal, the earliest available time of arrival.

After determining the time of arrival to the destination user terminal, the base station proceeds to step 530 decisions to determine whether a previously defined arrival time of initial assignment to a user terminal. There is a possibility of uneven interference for different users associated with different times of arrival, if the scheduled arrival times are periodic. Thus, if the arrival time is not the primary determining the time of arrival, the base station proceeds to step 532 and endomysium appointment time to come. The base station can randomize the assignment of the time of arrival and send a randomized value of the user terminal. In another embodiment, the base station and the user terminal can individually determine the arrival time on the basis specified in the function, after the base station will transmit the initial appointment time user terminals. The base station then proceeds to step 540.

If at step 530 the decision appointing the time of arrival is the first purpose of the time of arrival of the user terminal, there is no need to randomize the arrival time, and the base station may go directly to step 540.

At step 540, the base station determines the channel code for the destination user terminal. The base station may assign a different channel code to the user terminal for each transmission cycle to allow multiple user terminals to use one and the same time. Usually, the number of codes is limited to reduce the complexity of the receiver in the base station. In other embodiments, the implementation of all user terminals use the same code, and step 540 may be omitted.

The base station proceeds to step 550 for transmission to the destination time of arrival of the user terminal. For example, the base station can transmit the arrival time of the user terminal through the signaling in a straight line.

After the transfer destination arrival time of the base station proceeds to step 552 and transmits the channel assignment code. If all user Ter inaly use the same code, the base station is not required to transmit the code to the user terminal.

The base station proceeds to step 560 decisions and determines whether the base station receiver of the message is completed from the user terminal. The user terminal can transmit the complete message to indicate the completion of an active session.

If the base station receives the complete message, the base station proceeds to step 570, the method 500 is becoming completed to the user station. If at step 560 decisions receiver base station does not accept the message has completed, the base station may decide that a session remains active. The base station may then return to step 510, in order to maintain synchronization with the user terminal and to determine the next arrival time for the destination user terminal. The base station can determine the arrival time at each transmission cycle, or may determine the time of arrival less often. For example, the base station may re-define the arrival time, if the number of active users changes. In other embodiments, the base station may re-define the arrival times after a specified number of cycles of transmission. Other options for implementation may use other the means.

Figure 6 presents a flowchart of the sequence of operations variant of the method 600 of work in a limited time joining the channel. The method 600 may be implemented, for example, one or more of the user terminals 1 or 3.

The method 600 begins at step 602, when the user terminal transmits to the base station a request for access to the channel. The user terminal may send a request, for example, on a service channel random access to the base station.

The user terminal proceeds to step 610 and is synchronized with the base station for setting the total time support. During the synchronization process, the user terminal can determine the offset time, which can be used to compensate for the propagation delay.

The user terminal proceeds to step 620 and receives or otherwise determines the assignment of the time of arrival. User terminal usually takes the initial purpose of the time of arrival from the base station. However, subsequent the arrival times can be independently determined user terminal. For example, the user terminal can accept the appointment time in units of the duration of the elementary signal modulo the number of active user terminals. The user is Yelsk terminal may then continue to set your appointment time coming, if there is no change in the designation of or change in the number of active user terminals. In another embodiment, the user terminal can accept the appointment time of arrival and may determine the subsequent arrival times, based on some specified function.

After taking or identify the purpose of the time of arrival of the user terminal proceeds to step 630 to determine whether or otherwise determines the intent of the code. In systems where the user terminals can use more than one code, the base station may, for example, to define a channel code based on the destination time of arrival. In other embodiments, the implementation of all user terminals can use the same code they may not be assigned.

After identifying code of the user terminal proceeds to step 640 and transmits the data calculated in the time to come to the base station at the scheduled time of arrival. The user terminal transmits data in the time before the scheduled time of arrival, in order to compensate for the propagation delay from the user terminal to the base station.

The user terminal can buffer data to be transmitted, the waiting time for the opportunity to transmit. Polzovatelyami can then retrieve some or all buffered data and to transmit the data, so that the data will arrive at the base station, starting at the scheduled time of arrival. The user terminal may be configured to generate data with one of a specified number of dimensions of data blocks or can be configured to generate a data block of variable size. Data can be encoded using the assigned code that can be generated using, for example, of a shift register with linear feedback (LFSR).

After a data transfer, the user terminal proceeds to step 650 solutions and determines whether it should release its part of a limited time of arrival of the channel and end the active session. If not, the user terminal goes back to step 610 and continues to work in the channel.

If at step 650 solutions user terminal determines that the active session should be completed and access to the limited time of arrival channel released, the user terminal proceeds to step 652 and transmits the complete message to the base station. In one embodiment, the user terminal transmits a message of completion of service random access channel used by the user terminal for the initial request access to the channel. In another embodiment, the message is completed to viewlocity in the data transmitted for a limited time joining the channel. After the message transmission is complete, the user terminal proceeds to step 660 and the method 600 ends.

Figure 7 presents a flowchart of the operational sequence of a variant implementation of the method 700 of receiving the signal from the limited time of arrival of the channel. The method 700 may be implemented, for example, in the base station 4. The method 700 begins at step 710, where the base station receives, for a limited time joining the channel transmission from the at least one active user of the terminal and usually from the set of active user terminals. The base station proceeds to step 720 and determines the assignment of the time of arrival for a particular user terminal from the set of active user terminals. The base station then proceeds to step 730 and searches for transmissions from the user in a time window that overlaps the arrival time assigned to the user terminal. The base station may receive multiple transmissions modulated with the same code. Typically, however, each of the transmission is configured to have a different appointment time to come. Different signals thus modulated at the beginning in different time intervals. If the arrival times designate the I in increments, which are sufficient mutually correlation properties of the code, the base station can recover the transmission from the specific user terminal in the presence of other signals.

This disclosure describes a limited time joining a channel, which can eliminate the need for a large number of codes C, therefore, simplifies the receiver and at the same time substantially eliminates the likelihood of collisions. The wireless communication system can implement the channel as part of the alarm reverse lines of communication between multiple user terminal and one base station. The receiver in the base station can be significantly simplified, since reduced the number of codes to be searched every time.

The stages of the method, process, or algorithm described in connection with open options for implementation, can be implemented directly in hardware, in a software module, executable by the processor, or a combination of these means. The various stages or steps in the method or process can be performed in the order shown, or may be performed in a different order.

A software module may reside in random access memory (RAM), flash memory, volatile memory, permanent memory (ROM), programmable ROM (EPROM), electrical devices the ski erasable programmable ROM (EEPROM), registers, hard disk, removable disk, ROM, CD-ROM (CD-ROM) or on the storage media of any other shape known in the art. Illustrative media is associated with a processor so that the processor can read information from the media and record information on the medium. In the alternative, the carrier may be embedded in the processor. Additionally, various methods can be performed in the order shown in the variants of implementation, or can be performed using a modified procedure of stages. Additionally, one or more of the steps of the processes or methods may be skipped or one or more of the steps of the processes or methods can be added to methods and processes. An additional stage, the unit or activity may be added to the beginning, end, or between the existing elements of the methods and processes.

The foregoing description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be obvious to a person skilled in the art, and certain General principles can be applied to other variants of implementation without departing from the spirits or scope of the invention. Thus, the image is eenie not assume limited shows a variant implementation, and it should correspond to the largest amount that is compatible with open principles and new features.

1. The way to assign access to the channel, and the method contains

receiving a request for access to the channel from the user terminal and the user terminal is one of a number of active user terminals;

the timing of the transmission cycle as a result of the receipt of the request for channel access;

determining the time of arrival of the data within the transmission cycle for the user terminal;

the purpose of the time of arrival of the data to the user terminal and the transmission time of arrival of the data to the user terminal to assign a channel to the user terminal starting with the time of arrival of the data.

2. The method according to claim 1, in which the time of arrival of the data is in the time period in which at least one additional user terminal from a variety of user terminals transmitting.

3. The method according to claim 1, in which the time of arrival of the data is approximately the duration of one elementary CDMA signal from the time of arrival of the data assigned to the secondary user terminal from a variety of user terminals, which carries out the transfer.

4. JV the property according to claim 1, in which the time of arrival of the data is at least one elementary CDMA signal from the nearest time of arrival of the data assigned to the secondary user terminal.

5. The method according to claim 1, in which the time of arrival of the data have essentially the same position relative to the beginning of the transmission cycle.

6. The method according to claim 1, wherein the transmission cycle has a duration which is proportional to the duration of elementary CDMA signal.

7. The method according to claim 6, in which determining the time of arrival data contains the identification of the elementary CDMA signal modulo the number of elementary signals in the cycle of transmission.

8. The method according to claim 1, wherein the transmission cycle has a duration proportional to the number of active user terminals.

9. The method according to claim 1, wherein the transmission cycle has a fixed duration.

10. The method according to claim 1, additionally containing a randomized time of arrival of the data in the cycle of transmission.

11. The method according to claim 1, additionally containing a definition of the purpose code for the user terminal; and a transfer destination code user terminal.

12. The method of data transmission in the channel, and the method comprises requesting access to the channel;

the reception destination time of arrival of the data in response to the request; and transmitting the data block are offset in time and from the time of arrival of the data, so the initial part of the block of data arrives at the receiver at the scheduled time of arrival of the data.

13. The method according to item 12, in which the access request to the channel contains a request channel access channel random access.

14. The method according to item 13, in which the random access channel includes a channel CDMA Aloha.

15. The method according to item 12, in which the reception time of arrival of the data includes receiving the boundaries of the elementary CDMA signal in the cycle of transmission.

16. The method according to item 12, in which the reception time of arrival of the data contains the reception time of arrival of the data, separated essentially one duration of elementary CDMA signal from appointment time to another user's terminal.

17. The method according to item 12, in which the reception time of arrival of the data contains the reception destination period of time modulo the number of active user terminals.

18. The method according to item 12, which additionally contains the encoding of the data block using the code used at least one other user terminal, which transmits on the channel at the time that overlaps, at least partially, the time required to transfer a data block.

19. The method according to item 12, which additionally contains the encoding of the data block using the code that is used by many active user terminals.

20. The method according to item 12, the more the tion contains the definition of the future destination time of arrival of the data in the subsequent cycle of transmission, partly on the basis of the destination time of arrival of the data.

21. The method according to claim 20, in which the definition of the future destination time of arrival of the data contains the definition of the boundaries of the elementary CDMA signal modulo the number of active user terminals.

22. The method according to claim 20, in which the definition of the future destination time of arrival of the data contains the definition of the boundaries of the elementary CDMA signal, based on the predetermined algorithm.

23. The method of receiving data in the channel, and the method contains

receiving a request for access to the channel from the user terminal and the user terminal is one of a number of active user terminals;

the definition of a cycle transmission as a result of the receipt of the request for access to the channel;

determining the time of arrival of data in a loop transmission; determine the time of arrival of the data to the user terminal; receiving from the set of active user terminals; searching within a time window that includes the time of arrival of the data, for transmission from the user terminal; and receiving a block of data from the user terminal.

24. The method according to item 23, further comprising

the definition of quality metrics of a received signal corresponding to at least part of the data block.

the definition is of message output control partially based on the quality metrics of a received signal; and

transmission power control of the user terminal.

25. The method according to paragraph 24, in which the quality metric of the received signal contains the frequency of occurrence of erroneous symbols.

26. The method according to paragraph 24, in which the quality metric of a received signal contains a bit error rate.

27. Device for receiving and transmitting data in a limited time of arrival of the data channel, and the device contains

a receiver module for receiving the channel request from the user terminal;

module transmission cycle, designed to determine the cycle time of the transmission after receiving the channel request;

the module boundaries of time, designed to determine the time of arrival of the data in the cycle of transmission to the destination user terminal; and

a transmitter for transmitting time of arrival of the data to the user terminal to assign a channel to the user terminal starting with the time of arrival of the data.

28. The device according to item 27, in which the module transmission cycle determines the transmission cycle having a duration that is essentially equal to the duration of a specified number (D) of the elementary signals of CDMA.

29. The device according to p in which the module boundaries of time determines the time of arrival of the data, relevant to the respective boundary elementary CDMA signal.

30. The device according to p in which the module boundaries of time determines the time of arrival of the data corresponding to the boundary of the elementary signal CDMA module D.

31. Storage device, readable by a processor, configured to store one or more used by the processor commands, which when executed by the processor enable the method comprising

receiving a request for access to the channel from the user terminal; synchronization of the time base with the user terminal; determining transmission cycle as a result of the receipt of the request for access to the channel, and the transmission cycle has a duration proportional to the duration of the elementary signal CDMA;

determining the time of arrival of the data falling on the boundary of the elementary signal in the cycle of transmission; and

the transmission time of arrival of the data to the user terminal to assign a channel to the user terminal, from the time of arrival of the data.