RU2123763C1 - Method for time share of channels in mobile radio communication networks - Google Patents

Abstract

FIELD: radio engineering. SUBSTANCE: method of channel time share involves compression of continuous signal flows of user messages into periodical signal packets according time chart of channel time share, forming group packet flow of message signals, in which packets of information signals are interlaced with protection time intervals and intervals for synchronization signal transmission, and packets of information signals, and modulation of transmission line carrier frequency upon sending. Upon receiving method involves demodulation of radio signal, detection of synchronization signal, which provides number of target time-shared channel in group flow of packets of user signals, and regeneration of source continuous message from packets of information signals of target time-shared channel. Time chart of communication system operations is equipped with additional time intervals for measurement of user signal levels and signal distribution duration for which base station measures levels of received signals of user sets, compares measured signal levels and forming groups of users with close values of signal levels. In each group of users with close signal levels equal target channel number is assigned. Then signals of group of users of each time channel is additionally split into code channels. In addition during additional code channel sharing, packets of information signals from each user are encoded by a signal from set of semi- orthogonal M sequences or orthogonal Walsh-type signals. In order to achieve their effective share in common bandwidth of signal receiving by base station, user sets emit signals advanced by double time for distribution of radio signal from base station with respect to received synchronization signals from base station. When base station receives signals of user sets, it processes them according to type of their encoding signals, detects group packets of time-shared channel signals and regenerates source continuous information signal from packets of signals of target time-shared channel. EFFECT: low-rate transmission of group signal for many users.

Description

 The invention relates to the field of radio communications and may find application in digital systems of mobile radio communications.

 The main task in the development of digital mobile radio communication systems is to determine the methods for generating and processing signals that ensure high reliability of message transmission, as well as the compatibility of mobile radio communication systems with each other and with stationary networks, including packet data networks.

 Known cellular telephone system with an extended spectrum of signal transmission, described in patent EPO N 0484918, H 04 B 7/26 (US priority). This system contains many areas with voice communications equipment between mobile and fixed telephone exchanges.

 The disadvantage of this system is the high level of mutual interference due to the large dynamic range of signal levels of subscribers, bulky equipment.

 Known communication system with code division multiplexing described in PCT patent N 92/00639, H 04 L 27/00 (US priority). In this system, CAPs are formed to create quasi-orthogonality between users in order to reduce mutual interference, increase throughput and improve communication line performance. The information transmitted over the channels of the communication line is carried out mainly by a code sequence.

 The disadvantage of this system is the complexity of the electromagnetic compatibility of signals in a complex of radio stations operating in the common frequency band with a large dynamic range of changes in the levels of radio signals. Known communication system "Qualcomm" (USA, "Qualcomm". May, 1992).

 This system also uses code division multiplexing. When receiving a signal from one subscriber at the base station, interference from all (M-1) remaining subscribers of the radio communication system will be present. To eliminate or reduce this effect in the system, all subscribers in the coverage area of the base radio station are divided into groups, the levels of radio signals in each of which are aligned at the input of the receiver of the base radio station by changing the emitted signal power of each subscriber in this group. The equalization of signal levels in one group of subscribers can be carried out by a corresponding change in the power of the emitted signal from each subscriber according to the commands of the base radio station based on the results of measuring the levels of incoming signals.

 But this principle of operation of the system requires very high accuracy of the automatic power control system, which leads to the complexity of the technical solution of this system.

 The closest in technical essence to the proposed method is the method used in the "Pan-European Digital Cellular Communication System" (GSM), described in the article by Yu. A. Gromakov and V. I. Zhuravlev, "Formation and Processing of Signals in Communication Systems with Moving Objects" (J. "Express Information", a series of "Information Transfer", under the editorship of M.D. Venediktov, M., 1994, N 28).

 This method is based on the temporary separation of message channels. In the time division process, continuous streams of subscriber message signals are compressed into periodic packets in accordance with a time diagram of a multi-channel time division of channels in which channel time intervals are alternated with guard time intervals and time intervals of synchronization of radio stations of the base station subscribers.

 In this method, when implementing a reliable synchronization system, the time channels are strictly orthogonal and provide low levels of mutual interference in the communication channels. However, the need to introduce protective time intervals between channels and the high transmission speed of a group signal with a large number of subscribers sharply limit the possible number of communication channels that can be implemented with a large spread in the values of the propagation time of the radio signal from the far and near subscribers to the base station.

 To eliminate this drawback in a method based on the temporary separation of channels for transmitting messages, in which during the process of temporary separation continuous flows of signal signals of subscribers are compressed into periodic packets in accordance with the time diagram of multi-channel time division of channels, channel time intervals are alternated with protective and other service time by intervals, including time intervals of mutual synchronization of subscriber radio stations and the base radio station, in the process of entering In connection with the base station, subscribers measure the levels of the received signals, compare the measured values of the levels with each other, combine the subscribers into groups with similar values of the signal levels, and then each group of subscribers with similar values of the signal levels is assigned the same time channel number, and coordination the signal level of each subscriber with the number of the time channel is periodically repeated in the corresponding service time intervals, and then the time channels are additionally compressed with code and channels, moreover, in one code-time channel, the subscriber’s message is encoded with one of the ensemble signals of the quasi-orthogonal type of SRP or orthogonal signals of the type of Walsh functions or MCT, mutually shared in the common frequency band of the base radio station with other code signals of other subscribers in other code-time channels, received code signals subscriber stations are processed in accordance with the type of coding signals, message packets of each subscriber are restored from the group of code channels, and then the message packets They convert (depacket) the original (transmitted) continuous signal.

 Let us consider in detail the physical processes and timing diagrams of the operation of the radio communication system with the proposed method of code-time signal compression.

 The existing zone (cellular) radio communication systems of previous generations overwhelmingly used frequency division of channels (parallel asynchronous exchange of message signals). The separation of subscriber signals in such systems was carried out using bulky frequency-selective devices (filters).

 Currently, two new directions have been developed and are being developed for constructing public cellular (area) radio communication systems - these are, respectively, with time division of channels and code, based on ShPS with small base values (63-255).

 Systems with time division of channels (serial transmission of message signals in time) require synchronous operation of the entire collective of subscribers served by the base radio station. At the same time, the time channels are strictly orthogonal and are most effective from the point of view of mutual interference levels with a large dynamics of the signal levels of subscribers arriving at the base station. However, in order to preserve the orthogonality property of time channels in operating conditions when the subscribers of the communication system are at different distances from the radio base station, it is necessary to introduce protective time intervals between adjacent time channels. The value of the protective time intervals is determined by the propagation time of the radio signal from the base station to the most distant subscriber in the area served by the base station. To the protective time interval, time delays are added, determined by the signal transit time in the transmitting and receiving paths of the communication equipment. In addition, the timing diagram of the communication system should contain service time intervals for synchronization of the entire subscriber collective in the served area. As a result of introducing all the listed additional (non-informational) time intervals into a group signal, the efficiency of using the time resource adopted for temporary compression of subscribers' message signals decreases. That is, with the same admissible delay value for delivering a message with an increase in the number of chopped time channels, the duration of the message packet transmitted in one time channel is reduced, and the value of the additional time intervals remains unchanged. The ratio of the time spent on messaging to the total time allocated to one time channel is reduced. In addition, when implementing the temporary separation of a large number of channels, the transmission speed of a group signal increases proportionally, and at high speeds of message sources there are difficulties in processing a group signal due to high requirements on the speed of the element base.

 Communication systems with code division of channels are asynchronous, but the parallel exchange of message signals in such systems, in contrast to frequency division of channels, is carried out in the common for all subscribers frequency band allocated to the communication system. The indicated property is determined by the quasi-orthogonality of the BSS signals based on the SRP at arbitrary time shifts of the subscriber signals. However, the non-orthogonality of address signals based on SRP formed on generators of different types of polynomials leads to mutual interference in communication channels. The levels of this interference are determined by the mutual correlation properties (FCF) of the address bandwidth and depend on the dynamic range of the signal levels of the subscribers and the length of the bandwidth. At small lengths of the SRP, the levels of mutual interference are significant, their reduction requires a decrease in the number of simultaneously served subscribers in a given frequency band. However, in order to increase the efficiency of using the frequency resource allocated to the communication system, measures are being taken to reduce the levels of mutual interference in the communication system. These include adjusting the level of power radiated by subscribers according to the commands of the base radio station, normalizing (equalizing) the levels of subscribers' signals at the input of the receiver of the base radio station, and dividing the signals of spatially distributed subscribers into groups using directional antennas. The rational number of independent sectors for viewing the antenna system is in the range of 4-6, respectively, 4-6 times the total number decreases the number of subscribers that interfere with each other. However, these technical solutions are difficult to implement and are not always acceptable for tactical reasons for using a communication system.

 Thus, each of the considered methods of channel division during the construction of a cellular (zone) radio communication system has its own drawbacks. Systems with time division of channels with a large number of subscribers are not very effective and require high-speed element base when developing devices for processing a group signal. Communication systems with code division of channels have a high level of mutual interference with a large number of served subscribers and are also ineffective when used in mobile systems and under the influence of intense interference.

 At the same time, despite the different physical principles laid down in the temporary and code division of the channels, they have a common property - they work quite well with a relatively small number of communication channels. Based on this, the question arises about the feasibility and advisability of building a multi-channel cellular (zone) radio communication system based on a combination of the physical principles of time and code division of channels in a single communication system. Moreover, with such a combined construction principle (parallel-serial transmission of message signals), the number of channels of each type should be relatively small. In particular, when implementing 5-10 time channels and then dividing each time channel into 4-8 code channels, the total number of channels implemented in the communication system can be from 20 to 80.

 The following is an analysis of the options for constructing a zone (cellular) radio communication system based on everything said here.

 The use of only SHPS (pure code division of channels) in multichannel mobile radio communication systems is hampered by the complexity of ensuring electromagnetic compatibility of signals (EMC) in a team of radio stations operating in the common frequency band with a large dynamic range of changes in radio signal levels.

Вследствие этого и наблюдается подавление принимаемого сигнала в одном канале (одной структуры ПСП) сигналом другого канала (другой структуры ПСП), если уровень сигнала от мешающего канала в канале приема сообщения в

раз больше, чем уровень принимаемого сигнала.The latter is explained by the non-orthogonality of the radio signals generated in different channels by pseudo-random sequences (PSP) of different types. Even some of the best PSM, M-sequences, on average, have relative outliers of mutual correlation functions (VKF) equal to

As a result of this, suppression of the received signal in one channel (one SRP structure) by the signal of another channel (another SRP structure) is observed if the signal level from the interfering channel in the message receiving channel is

times greater than the level of the received signal.

если уровни помех суммируются по среднеквадратичному закону. В частном случае Б=1023 и М=60 сигнал/помеха в канале приема 0,75-1, т. е. такая система неработоспособна даже при выравнивании сигналов всех абонентов. Для снижения уровня системных помех, т.е. увеличения отношения сигнала к помехе до приемлемой величины, например 10 дБ, число мешающих сигналов должно быть уменьшено до 5-25 в зависимости от значений ВКФ выбранных ПСП. Из этого следует, что единственный путь реализации системы с кодовым разделением достаточно большого числа каналов при использовании соответствующего ансамбля ПСП - это разбиение всех абонентов в зоне действия базовой радиостанции на группы, уровни радиосигналов в каждой из которых выравниваются на входе приемника базовой радиостанции изменением излучаемой мощности сигнала у каждого абонента данной группы. Причем уровни сигналов абонентов других групп на входе устройств кодового разделения сигналов базовой радиостанции должны быть значительно ослаблены относительно уровней сигналов данной группы. Так, в рассматриваемом примере для обеспечения

при приеме сигналов от каждого из 60 абонентов нужно всех абонентов поделить на 3 группы по 20 абонентов в каждой. Необходимое взаимное ослабление сигналов между группами абонентов может быть достигнуто разбиением всей зоны действия базовой радиостанции на 3 сектора с помощью 3-х направленных антенн, сектор обзора каждой из которых составляет 120^o. В каждом секторе при этом будет обслуживаться 20 абонентов. Выравнивание уровней сигналов в одной группе абонентов может быть осуществлено соответствующим изменением мощности излучаемого радиосигнала у каждого абонента по командам базовой радиостанции на основании результатов измерения уровней приходящих сигналов.When operating a multi-channel zone (cellular) radio communication system with code division multiplexing in the signal receiving channel of one subscriber, interference from all (M-1) remaining subscribers of the radio communication system will be present at the base station. The ratio of the signal to system interference in the case of equality at the base station of all M incoming radio signals will be a value close to the value

if the interference levels are summed according to the mean square law. In the particular case of B = 1023 and M = 60, the signal / interference in the reception channel is 0.75-1, i.e., such a system is inoperative even when the signals of all subscribers are aligned. To reduce system interference, i.e. increasing the signal-to-noise ratio to an acceptable value, for example, 10 dB, the number of interfering signals should be reduced to 5–25, depending on the VKF values of the selected SRP. It follows that the only way to implement a system with code separation of a sufficiently large number of channels using the corresponding ensemble of the SRP is to divide all the subscribers in the coverage area of the base station into groups, the levels of radio signals in each of which are aligned at the input of the receiver of the base station by changing the emitted signal power each subscriber of this group. Moreover, the signal levels of subscribers of other groups at the input of the code separation signals of the base radio station should be significantly attenuated relative to the signal levels of this group. So, in this example, to ensure

when receiving signals from each of 60 subscribers, it is necessary to divide all subscribers into 3 groups of 20 subscribers in each. The necessary mutual attenuation of signals between groups of subscribers can be achieved by dividing the entire coverage area of the base radio station into 3 sectors using 3 directional antennas, the field of view of each of which is 120 ^o . In each sector, 20 subscribers will be served. Alignment of signal levels in one group of subscribers can be carried out by a corresponding change in the power of the emitted radio signal for each subscriber according to the commands of the base radio station based on the results of measuring the levels of incoming signals.

где γ - коэффициент ≥ 1, учитывающий фактическое увеличение значения ВКФ, если у всех (М-1) абонентов ошибка регулирования одинакова и приводит к одинаковому возрастанию уровней сигналов помех на входе приемника базовой радиостанции. При сохранении требования к качеству приема 10 дБ взаимосвязь между M и γ может быть выражена в явном виде

так как увеличение уровней помех может быть скомпенсировано только уменьшением числа одновременных переговоров M. Из последнего видно, что при ошибке регулирования мощности в 3 дБ (γ=1,41) допустимое число абонентов в одной группе снизится в 2 раза и станет M=13, а при 6 дБ (γ=2) - M=7. Если к тому же учесть, что высокую точность АРМ нужно выдерживать при изменениях регулируемой величины в пределах > 80 дБ и на фоне помех, то становится ясной сложность технических решений, сопровождающих данное направление реализации системы связи.We carry out a simplified (approximate) assessment of the required accuracy of the automatic power control system (AWP). To do this, consider the expression

where γ is a coefficient ≥ 1, taking into account the actual increase in the VKF value, if for all (M-1) subscribers the control error is the same and leads to the same increase in the levels of interference signals at the input of the receiver of the base radio station. While maintaining the requirements for the reception quality of 10 dB, the relationship between M and γ can be expressed explicitly

since an increase in interference levels can be compensated only by a decrease in the number of simultaneous conversations M. From the last it is seen that with a power control error of 3 dB (γ = 1.41), the allowable number of subscribers in one group will decrease by 2 times and become M = 13, and at 6 dB (γ = 2) - M = 7. If we also take into account that the high accuracy of the workstation must be maintained with changes in the controlled variable within> 80 dB and against the background of interference, it becomes clear the complexity of the technical solutions that accompany this direction of the communication system.

 Under the influence of powerful sighting and barrage deliberately organized interference of their own noise immunity, an APS may not be enough and it is necessary to consider the issue of a combination of an APS with frequency hopping (effective for high-power interference) and a frequency-adaptive mode (effective for powerful obstructive interference). The implementation of these measures, in particular the frequency hopping frequency, requires the introduction into the communication system of both the synchronous operation mode of the entire collective of subscribers and the consolidation of the transmission time of message signals by time intervals for the restructuring of radio stations by frequencies and their mutual synchronization.

 Further clarification of the essence of the proposed method should be based on the properties of the signals.

 Correlation properties of signals. From the analysis of the existing direction of building a communication system with code division of channels, it follows that the main problems that arise during its implementation are associated with insufficiently good VKF of a non-orthogonal ensemble of signals built on various types of SRP (different generating polynomials). These problems are significantly complicated with a large dynamic range of possible changes in the levels of NPS radiated in the common frequency band.

и АКФ=1/Б. Так, например, для периодического сигнала с базой Б=31 боковой лепесток равен 1/31 при всех сдвигах -τ ≥ τ ≥ +τ. Моделирование же 6-ти ВКФ периодических сигналов с базой Б=31 показало, что их боковые лепестки существенно больше, достигают значений до 9-11/31. Этот же вывод следует и из приведенной выше расчетной формулы для оценки усредненных характеристик выбросов ВКФ.At the same time, it is well known that the autocorrelation functions (ACF) of the SRP, in particular, M-sequences, have significantly lower emissions of side lobes. This conclusion follows directly from comparing expressions for

and ACF = 1 / B. So, for example, for a periodic signal with base B = 31, the side lobe is 1/31 for all shifts -τ ≥ τ ≥ + τ. Simulation of 6 VKF periodic signals with base B = 31 showed that their side lobes are much larger, reaching values up to 9-11 / 31. The same conclusion follows from the above calculation formula for estimating the averaged emission characteristics of HCF.

 Ensemble of signals. It is necessary to pay special attention to the fact that all cyclic shifts of the SSP of the same type have the same ACF = 1 / B for −τ ≥ τ ≥ + τ. The latter circumstance suggests that we try to use all possible cyclic shifts of a pseudo-random sequence of the same type for signal separation. The maximum possible ensemble of separable signals based on cyclic shifts and possessing ACF properties will be equal to the value of B / 2 for obvious reasons. So for values without a signal B = 31; 63; 127; 255; 511 and 1023 signal ensembles will be equal to 15, respectively; 31; 63; 127; 255 and 511. For comparison, we write out ensembles of M-sequences of different types for the same base values: 6; 6; 18; 16; 48 and 60. The advantage is clearly on the side of cyclic shifts.

 The operation of the communication system on cyclic shifts. It is important to note that the specific value of the cyclic shift number set from the base station to the subscriber as a code channel determines a certain time shift of the assigned SRP signal relative to the reference initial time point stored on the base station. Therefore, any additional time shifts of the SRP signal coming from the subscriber to the base station will also lead to additional shifts relative to the initial reference time at the radio base station. Moreover, depending on the magnitude of the additional time shift, the cyclic shift number assigned to this subscriber will go into the cyclic shift number of the other subscriber. The same will happen with the signals of all the other subscribers of the multichannel communication system with code division of channels built on the cyclic shifts of the memory bandwidth. Those. in the presence of additional time shifts for subscribers, identification of subscribers' signals at the base radio station is not possible.

 When transmitting messages from the base station to the subscriber, the entire ensemble of signals at cyclic shifts of the SRP is formed from one reference generator, and therefore the problem of additional relative time shifts of the signals radiated to the subscribers does not exist.

 With conventional methods of synchronizing a communication system, additional time shifts of signals always exist. First of all, these are delays due to the propagation time of the radio signal from the base station to the subscriber when establishing cyclic and element-by-element synchronization. Those. the initial moment itself, relative to which the subscriber will count the assigned shift number of the SRP, will already be shifted relative to the reference moment of time stored at the base radio station. Then the delay in the propagation of the radio signal from the subscriber to the base station will increase the additional shift.

 Thus, the common methods for synchronizing narrow-band and broadband radio communication systems, which give a delay of clock pulses in synchronized radio stations, are not applicable here. The way out of this deadlock is possible only by searching by constructing a special synchronization system that eliminates additional time shifts of the PSP signals coming from subscribers with respect to the reference time stamps stored at the base radio station. Those. the synchronization system for subscribers must generate clock pulses of signal transmission with a lead time of twice the propagation time of the signal relative to clock pulses extracted from the signals of the base radio station.

 In addition to the above, for the full realization of the advantages of the method of addressing signals with cyclic shifts of the SRP, it is necessary to modulate complex signals with messages without violating the indicated mutual correlation properties of the subscribers' signals.

 The solution to the problem of a large dynamic range of signal levels of subscribers. The existing direction for solving the problem of the multi-channel radio communication system with code division multiplexing is to divide the subscribers in the coverage area of the base station into separate groups of subscribers using directional antennas that divide the entire territory around the base station into separate sectors. The number of allocated subscriber groups and, accordingly, the number of viewing sectors of the antenna devices of a base radio station is determined by the ratio of the total number of subscribers to be served by this base radio station to the number of subscribers combined into one group. In turn, the number of subscribers united in one group is determined by the requirements for the quality of message isolation (signal-to-noise ratio) at the base station, depending on the VKF PSP and the accuracy of the operation of the system for regulating the radiation power of signals from subscribers. The main technical problem is the implementation of a high-precision (error of a decibel unit) system for automatically adjusting the radiated power of signals from subscribers based on the signals of a radio base station in a large range of controlled variable (≈ 80 dB) and against a background of interference.

 Significantly simplify the solution to the problem of automatic adjustment of signal strength among subscribers or completely eliminate AWP by introducing classification of subscriber signal levels at the base radio station along with a code for temporal separation of channels. Moreover, with code-time compression of signals, B temporary channels are first formed, each of which is then compressed with K code channels. The resulting number of code-time channels is determined by the value M = B • K.

 The same temporary position is assigned to those K subscribers whose signal levels are close to each other within the accuracy of level measurement. Those. when a subscriber’s channel number is assigned to the subscriber, an unambiguous correspondence is entered between the level of his signal at the receiver input of the base radio station and the time channel number. A general view of the time-division multiplexed signal is shown in FIG. one.

 As a result, at each time position, the subscriber bandwidth will be emitted with close levels, which in terms of the final effect is equivalent to an automated workstation within one subscriber group. The role of the directional sectors of the antenna review of the base station, separating the signals of one group from another, in this case, perform temporary positions. That is, now groups are created not by the principle of sectors, but by the principle of ring zones. The boundaries of one ring (the difference between the nearest to the base radio station and the far radii) are determined by the values of the minimum and maximum signal levels of subscribers grouped at one time position (Fig. 2).

The possible relative scatter δU of signal level values from minimum to maximum within the area of one ring zone at one time position depends on the number B of input time channels, estimation errors Δ _APO of signal levels and the maximum possible change in signal levels D of subscribers located near and at maximum range from the base station: δU dB = D dB / B if δU dB ≥ Δ _APO .

 In particular, if D = 80 dB, B = 5, then δU = 16 dB. At D = 80 dB, B = 15 and δU = 6 dB, which allows 3 dB signal level measurement errors.

In the process of classifying signals at a radio base station, signal levels of subscribers (entering into communication and already negotiating) are measured, then they are ranked, i.e. the measured values are arranged in increasing order of magnitude. The ranked series, represented by the measured values of the signal levels, will contain the minimum U ₍₁₎ and maximum U _(m) values. Index (i) at U _(i) means the sequence number of the subscriber's signal level in the ranked row. Based on the values of U ₍₁₎ and U _{(m), the} dynamic range of signal levels D dB is calculated through the ratio U _(m) : U ₍₁₎ . Next, based on the known number of temporary positions (channels) B, the permissible relative signal spread δU dB = D dB: B within the same zone is determined, the same for each time position. After converting the decibels δU dB to the ratio γ (times), the boundary voltage values, the minimum and maximum, are calculated for each time interval from B. So for the 1st interval, the lower boundary will be U ₍₁₎ , and the upper one (U ₍₁₎ • γ ) All subscribers whose signal levels fall between these boundaries are assigned the first time interval for communication. For the second interval, the lower bound is U ₍₁₎ • γ, the upper bound is (U ₍₁₎ • γ) • γ = U ₍₁₎ • γ ² , etc. until the last time interval in which the lower boundary is U ₍₁₎ • γ ^B-1 , and the upper boundary is U ₍₁₎ • γ ^B. As a result of all that has been said, a table can be compiled illustrating the sequence of actions when assigning a temporary channel number to subscribers in accordance with the ring zone of their location according to the results of measuring signal levels of subscribers and comparing them with boundary level values acceptable for each temporary channel.

With a small number of time channels B and a large dynamic range D of signal levels of subscribers, it is possible to further reduce the level of mutual interference due to the introduction of AWS in the group of subscribers of the same ring zone. However, the conditions for using the AWP are greatly simplified due to a decrease in the requirements for the regulation range of the power amplifier of a subscriber radio station by a factor of B. So, for example, if in a system with code division of channels (without additional time division) it is necessary to regulate the power within 80 dB (≈ 10 ⁸ times), then in a system with code-time division of channels when regulating the power of subscribers' transmitters located within the same ring zone , it is enough at B = 5 - within 6 times (16 dB); at B = 10 - 2.5 times (8 dB) and at B = 25 - 1.5 times (2.3 dB).

 The method of forming subscriber groups considered here by the principle of combining in one time channel those subscribers whose signal levels at the receiver input of the base radio station are close to each other, can have several implementation options. The most preferred, in our opinion, is the following.

 We will divide the process of leveling subscribers' signal levels into 2 stages: preliminary and final. In the preliminary stage, according to the results of measuring the radio signal level of the base radio station, subscriber radio stations coarsely set the power of their own transmitters corresponding to the lower limit of the quality of reception of message signals at the base radio station. As a result of this, the initial dynamic range of changes in signal levels arriving at the base station is reduced from 80-90 dB to 10-20 dB. At the second stage, the final leveling of subscriber signal levels to 2-3 dB occurs by combining subscribers in the same time channel with close signal level values.

 Let the radio stations of the subscribers of the zone (cellular) radio communication system before entering into communication measure the signal level of the base radio station. Moreover, each radio station will have its own rating, the value of which is determined by the distance of each specific subscriber from the base radio station.

Further, if we propose that at the maximum operating ranges of the base radio station, the boundary level of its signal U _gr. At the input of the subscriber receiver is equal to the level of the boundary signal U _{gr. A} from the subscriber transmitter at the input of the receiver of the base radio station, i.e. U _gr.b = U _gr.a , then the ratio of the measured signal value of the base station U _r.b. to its boundary value U _r.b / U _g.b will with some error correspond to the ratio U _r.a / U _g.a , where U _r.a is the signal level from the subscriber station at the input of the base station at the same mutual removal of the subscriber and base stations. From the latter it follows that according to the measured value of the signal level U _{rbb of the} base radio station, the attenuation of the power of the subscriber radio station can be predicted, leading to the level U _{gr.a of the} signal at the input of the base radio station, i.e. the necessary attenuation of the nominal radiation power of a subscriber radio station will be (U _r.b / U _g.b dB).

The previously introduced proposal on the equality of U _r.b / U _g.b = U _r.a / U _g.a will be valid if the same antenna is used for reception and transmission at the base radio station, as well as at the subscriber radio station , although the antennas themselves can differ from each other, and the radiation of the signals are produced at the same radio frequency. Then the four-port network, considered between the input and output terminals of the antennas of the transmitting and receiving sides, respectively, is linear and reversible.

 A more accurate correlation between the measured signal level of the base radio station and the amount of necessary attenuation of the transmitter power of the subscriber radio station for different transmitting and receiving antennas can be achieved in the preliminary calculations, taking into account the height of the antenna and the gain, the difference between the rated transmitters power and the sensitivity of the receivers of the base and subscriber radio stations and other factors. The calculation results can be recorded in the memory of the computer of the subscriber radio station in the form of a table.

As a result of the indicated binding of the signal levels of all subscribers distant at different distances from the base radio station to the same level U _gr.a at the input of the receiver of the base radio station (with a certain error θ _U ), the dynamic range of changes in the signal levels of subscribers arriving at base station. At the same time, the measurement of signal levels of subscribers in the process of their classification when assigning a temporary channel for message transmission can be made with higher accuracy, and the spread of signal levels of subscribers in one group of code channels of one temporary channel can be significantly reduced.

Indeed, if the transmitter powers of all subscribers correspond to the same signal level at the input of the base station with an error of θ _U = ± 5 dB (3 times), which is quite feasible, then an error of measurement of signal levels by the base radio station Δ _APO = ± 1 dB is achievable. After classifying subscriber signal levels and dividing them into 5 groups equalized by signal levels in a system with 5 time channels, the spread of subscriber signal levels in 1 time channel will be δU = 10 dB / 5 = 2 dB. Given the accuracy of measuring signal levels Δ _APO = ± 1 dB, the limits of measurement of signal levels in the 1st time channel will be from 1 dB to 3 dB. In the worst case, it will be 3 dB, γ = 1.4.

 Let us estimate the approximate number of code channels that can simultaneously work in the 1st time channel with a maximum spread of subscriber signals γ = 1.4.

при сложении системных помех в соответствии с квадратичным законом и С/П = Б/γ•АКФ•(K-1) при линейном сложении, для базы Б=31 получим K₁=15 при С/П=14 дБ в соответствии с 1-ой формулой, К₂= 5 при С/П=14 дБ и K₃=10 при С/П=6 дБ в соответствии со второй формулой. Если база сигнала Б=255, то 1-ая формула дает K₄=122 при С/П=24 дБ, а 2-ая формула приводит к K₅=12 при том же значении С/П=24 дБ и K₆=85 при С/П=6 дБ.Using the relations

when adding system interference in accordance with the quadratic law and C / P = B / γ • ACF • (K-1) with linear addition, for the base B = 31 we get K ₁ = 15 at C / P = 14 dB in accordance with 1 -th formula, K ₂ = 5 at C / P = 14 dB and K ₃ = 10 at C / P = 6 dB in accordance with the second formula. If the signal base is B = 255, then the first formula gives K ₄ = 122 at C / P = 24 dB, and the second formula leads to K ₅ = 12 for the same value C / P = 24 dB and K ₆ = 85 at S / N = 6 dB.

Taking into account all 5 time channels, the total number of subscribers served by the base station in accordance with the quality described above will be at B = 31: M ₁ = 75, M ₂ = 25, M ₃ = 50; and at B = 255: M ₄ = 610, M ₅ = 60 and M ₆ = 425.

It should be noted that the given values of K ₁ , K _3, and K ₄ correspond to the maximum possible values of ensembles of code signals constructed on cyclic shifts of the PSP with the minimum possible shifts through 2τ _PSP (extremely tightly packed ensemble). In the practical implementation of the communication system, it is apparently necessary to leave additional protective time intervals between adjacent cyclic shifts due to fluctuations in the propagation time of radio signals, which will lead to a corresponding reduction in signal ensembles.

 Analysis of the possible types of radio interference in extreme conditions of the system shows that it can be either deliberately organized or random interference. Obviously, the greatest danger is deliberately organized interference. They can be divided into sighting and obstructive. Under intense impacts of powerful intentional interference, the intrinsic noise immunity of the BSS will be clearly insufficient, since in case of code-time channel separation, the appropriate signal base values lie in the range 31-255.

 An effective method of protection against impact interference is frequency hopping. To ensure the possibility of introducing the frequency hopping mode into a radio communication system with code-time division of channels, it is necessary to provide additional (non-informational) time intervals in the time diagram of the system operation for tuning the radio station according to radio frequencies.

 Protection from powerful barrage interference affecting a group of frequencies in the selected range of radio waves can be provided by the frequency-adaptive mode of operation of the radio station. For its implementation, additional time intervals are also needed in the time diagram of the communication system for analyzing the interference situation at frequencies and transmitting commands to change the working frequency of the radio communication.

 With the combined effects of impact interference and powerful obstruction, it should be possible to comprehensively introduce noise-protected operating modes into the radio station: frequency hopping and frequency-adaptive.

 In addition to the introduction of the specified auxiliary time intervals into the time diagram of the operation of the radio communication system, special technical solutions should be provided that allow one to evaluate the noise levels at frequencies free of message transmission, evaluate the quality of the emitted message signals, generate unpredictable sequences of numbers that determine the sequence of tunings of radio stations by frequencies in frequency hopping mode, and for technical masking of messages.

 The listed special technical solutions have been developed, can be applied and implemented as VLSI in radio stations with code-time division of channels.

 To protect against anomalous errors, which are especially likely during code compression of signals due to non-orthogonality of the SRP, it is necessary to encode digital message signals with effective codes (for example, PC).

 For further specification of an embodiment of the method of code-time signal compression, specific time diagrams of the communication system operation are needed, which determine the algorithm of its functioning.

 Timing diagrams of the operation of the communication system were calculated for the implementation of the frequency hopping mode, the temporary separation of channels with the possibility of independent frequency hopping in each of the temporary channels, and the combined code-time channel separation also with the possibility of frequency hopping in each time channel. A feature of time charts (Fig. 3) is the presence of a service pause during which interference analysis can be performed in the allocated frequency band of the communication system for frequency adaptation and estimation of the propagation time of the radio signal from the subscriber to the base radio station, necessary for the implementation of proactive synchronization of signals transmitted from subscribers when time division multiplexing.

In addition to the service pause, the time diagrams of the communication system contain other time intervals that are free from message transmission. These include time intervals for synchronization of the communication system as a whole (T _sp = T _slots ), for the synchronization of transmitted messages in each time channel when transmitting messages with time division of signals (T _subsync. ), And for the restructuring of radio stations with _{frequency hopping} (T _perestroika ) including protective time intervals for the propagation time p / signal.

All calculated time diagrams have the same cycle duration (T _cycle = 5.28 s), the same number of block packets (33, 32 of them are informational, and one service), and each block packet with a duration of 160 ms contains the same the same number of slots containing message signals (16 slots, of which 15 are informational, and one is synchronizing). Slot durations in all modes are also the same and equal to 10 ms. The exact duration of the slot is determined by the transmission time of the 192 bit signal at a speed of 19.2 kb / s.

 In the mode of operation of a communication system with a time division of 5 subscriber channels, with a speed of 2.4 kb / s each, the slot contains 16 bits for tuning radio stations, 44 bits for sub-synchronization of a temporary channel and 132 bits of a transmitted message at a group speed scale of 19.2 kb / from.

 The frequency hopping mode with one time channel in FIG. 3 characterizes the limiting case of code-time signal compression, which is effective at close values of the signal levels of subscribers (for example, all subscribers of one object are negotiating with subscribers located in another object). The parameters of the frequency hopping diagram also contain a service pause of 160 ms, intervals for tuning and 16-bit sub-synchronization at a speed scale of 19.2 kb / s and a message length in one packet of 176 bits at the same group speed of 19.2 kb / s and the speed of message sources 16 kb / s

 An unconventional approach to solving the synchronization problem, eliminating the additional time shifts of the received bandwidth signals from subscribers relative to the reference bandwidth of signals at the base radio station, is as follows.

 Let the propagation time of the radio signal from the subscriber radio station to the base station equal to the propagation time of the radio signal from the base radio station to the subscriber station be exactly known. It is required to set the phase of the transmitting sync clocks in the transmitter of the subscriber radio station in such a way that the SRP signals transmitted by the subscriber radio station synchronized by them coincide without additional time shifts with the reference copy of the SRP signals generated by the base radio station.

 In the process of solving this problem, it is necessary to perform two main actions: compensate for the delay in the arrival of synchronization signals from the base station to the subscriber station and introduce a lead in time for the transmission of synchronization signals from the subscriber station to the base station with respect to the clock received as a result of delay compensation.

 To implement these actions, it is first necessary to set the transmitter sync clock generator synchronously and in phase with the clock received from the base station. Then shift the clock in time in the direction of phase advancement by an amount equal to the propagation time of the radio signal from the base station to the subscriber. As a result of the compensation of the phase of the synchronized clocks, they will exactly coincide with the synchronized clocks generated by the base station. However, if the SRP signals are emitted to the base radio station over these clock cycles, then the signals received there will be delayed relative to the corresponding reference copy generated by the base radio station for the time the radio signal propagates from the subscriber station to the base station. To eliminate the indicated delay, as already noted, it is possible to anticipate the time of radiation of the SRP relative to the synchrotacts of the base radio station. Those. the synchronization clocks obtained as a result of the previous compensation and exactly coinciding with the reference synchronization clocks of the base radio station are re-shifted in time in the direction of phase advance by the amount of time the radio signal propagates from the subscriber radio station to the base.

 The introduced proposal regarding the known time of propagation of a radio signal from a subscriber station to a base station is not a limitation when implementing the considered method of synchronizing a communication system with code division multiplexing, since the numerical value of the time of propagation of a radio signal can be directly measured by known methods, for example, using the same SHPS as for code division of channels.

 The essence of the proactive synchronization procedure for sending messages to subscribers is explained in FIG. 4. For its implementation, special time intervals are required in the time diagram of the communication system, allocated to estimate the propagation time of the radio signal from the subscriber station to the base station.

 In FIG. 5 discloses the essence of proactive subsynchronization of subscribers' message signals in each time channel during the transmission of information. Moreover, in the time diagram of the communication system, the corresponding additional time intervals are also required.

 Variants of the practical implementation of service time slots in the process of proactive synchronization and subsynchronization of subscriber code signals, accurate to one bit, tied to the time diagrams of the 5-channel system in FIG. 3 are shown in FIG. 6 and FIG. 7. By the signal “request of the base radio station”, subscriber radio stations synchronize their receiving devices, while adjusting the time intervals of their timing diagrams for receiving signals from the base radio station. Subscriber radio stations then emit a “response to request” signal sequentially in time, which is the beginning of the calculation of the propagation time of the radio signal from subscribers. Rigidly tied to the moment of reception of the signal “answer to the request” of each subscriber, the base station sequentially emits the signals “answers to answers” to the subscriber radio stations, the moment of arrival of which is recorded by each subscriber radio station and is the moment of the end of the calculation of the propagation time of the radio signal.

 Timing diagrams of the operation of signal packetizing and de-packetizing devices at the base and subscriber radio stations during the messaging process are shown in FIG. 8, and in FIG. Figure 9 shows a functional diagram of a system of proactive synchronization and subsynchronization of subscriber code signals in time channels.

 A single measurement of the delay time of a radio signal during its propagation is possible only when installing subscriber radio stations only at stationary objects. With moving objects, the delay time must be measured periodically, and the period of repetition of the measurement is determined by the speed of the object. If for measuring the delay time we use the same SHPS as for code division of channels, then there is a need for a temporary separation of procedures for estimating the propagation time of a radio signal, synchronization, and direct exchange of messages.

 The accuracy of measuring the delay time during the propagation of a radio signal can be very high if for these purposes using a BSS with a duration of one element of the bandwidth is significantly less than the accepted duration of the element of the information bandwidth (to evaluate the delay use a BSC with a larger base).

 The error incursion of the set time (subscriber movement, instability of the reference generators) between 2 adjacent measurements of the propagation time of the radio signal can be corrected directly by the information bandwidth by tracking devices for monitoring the delay of the received signal during message reception.

A functional diagram of proactive synchronization and sub-synchronization is shown in FIG. 9. It contains from the base of the radio station:
1 - OR circuit
2 - counter transmission time signal of the i-th response to the answer,
3 - shaper narrowband signal (UPS) according to the law of the SRP (length of 31 elements),
4 - shaper broadband signal (SHPS) according to the law of the SRP (length 1023 elements),
5 - counter delay time of the signal from the subscriber,
6 - counter start time of the time interval for receiving a response signal from the subscriber,
7 - discrete-matched filter (DSF) of a narrow-band signal in the form of SRP,
8 - shaper time intervals packetization signals (PAK PRD),
9 - the registrar of the moment of the end of the time delay account
10 - matched filter for a broadband signal (SHPS) in the form of SRP,
11 - counter refinement of the delay time of the signal,
12 is an OR diagram
13 - driver SHPS sub-synchronization,
14 - counter time interval for synchronization,
15 is a counter of the time interval for transmitting a request signal during sub-synchronization,
16 - counter time interval for receiving a response from the subscriber during sub-synchronization,
17 is a block correlation processing of broadband signals during sub-synchronization,
and from the subscriber radio station:
18 is a discrete-matched filter (DSF) narrow-band signal in the form of SRP,
19 is an OR diagram
20 - counter time interval for receiving a response signal response,
21 is a matched filter for a broadband signal (SHPS) in the form of SRP,
22 is a diagram for clarifying time intervals of a depacketator of signals based on "request" signals,
23 - shaper of the exact time of the end of the lead account,
24 - depacketator of received messages,
25 - shaper narrowband signal (UPS) according to the law of the SRP (31 elements),
26 is a time counter of a time interval for generating a response signal,
27 is a diagram for calculating a lead time of a radiation of a message signal,
28 - shaper broadband signal (SHPS) according to the law of the SRP (1023 elements),
29 is a correction chart of the current lead time value,
30 is a diagram for specifying lead times,
31 - shaper time intervals packetization signals
32 is a block correlation processing of wideband sub-synchronization signals,
33 is an OR diagram
34 is a counter of the time interval for the reception of the signal "request" during synchronization,
35 - driver SHPS sub-synchronization,
36 is a counter of the time interval for receiving response to response signals during sub-synchronization,
37 is a counter of the transmission time of the response signal during sub-synchronization.

 The listed blocks on the side of the base radio station are interconnected as follows. PAK PRD 18 with its outputs is connected to the inputs of the circuits OR 1 and 12, the inputs of the counters 2, 6, 14, 15 and 16. The inputs of the recorder 9 are connected respectively to the outputs of the PAK PRD 18 through the counter 6, DSF 7 and SF SHPS 10, and the output of the unit 9 is connected to the inputs of the counters 2 and 5. The output of the counter 2 through the OR circuit 1 is connected to the input of the shaper UPS ПСП 3, the output of which is connected to the input of the shaper ШПС ПСП 4. The output of the circuit OR 1 is connected to the input of the counter 5, the output of which is connected to the input of the unit range calculation. The output of the DSF 7 is connected to the input of the matched filter SHPS 10. The output of the delay refinement counter 11 is connected to the other input of the range calculation unit, and one of its inputs is connected to the output of the PAK PRD 8 via the OR 12 circuit, and the other input is connected to the output of the correlator block 17. Other inputs of the OR circuit 12 are connected respectively to the outputs of the counters 14 and 15, and its output is connected to the input of the SHPS shaper 13. The output of the counter 16 is connected to the input of the correlator block 17.

 On the side of the subscriber radio station, these blocks are connected as follows. The separator of the signal signals 24 is connected by its inputs to the output of the synchronization signal clarification unit 22, with one of the outputs of the counter 30, and the outputs - with one of the inputs of the OR circuit 19 and with the inputs of the counters 20, 34 and 36, respectively. The outputs of the counter 20 are connected to the input of the DSF 18 through the OR circuit 19 and with the input of the shaper of the exact moment of time 23, the other input of which is connected to the output of the DSF 18 and the input of the refinement circuit of the synchronization signals 22, and the third input of block 23 is connected to the output of the SF SHPS 21 in parallel with the input of the circuit of the refinement of synchronization signals 22. The output of the shaper 23 is connected to one of the inputs of the lead-time counter 27, the other input of which is connected to the output of the counter 26, in parallel to which the input of the shaper UPS 25 is connected. The output of the counter 27 is connected to the input of the current-generating circuit of the lead-time 29, to another input which is connected to the output of the prediction counter 30, and the outputs of the counter 29 are connected to the input of the PAK PRD 31 and the inputs of the circuits for the direct generation of the message signal. The output of the shaper UPS 25 is connected to the input of the driver SHPS 28. To the input of the counter 26 is connected the output of the PAK PRD 31, the remaining output of which is connected to the input of the counter 37 of the time interval for transmitting the response signal during sub-synchronization. The output of the counter 37 is connected to the input of the driver SHPS 35 signal synchronization. The outputs of the counters 36 and 37 are connected to the inputs of the OR circuit 33, the output of which in turn is connected to the inputs of the block of correlators 32 and the counter for determining the lead time 30.

 According to the timing diagram of FIG. 6, the system of proactive synchronization and sub-synchronization of message signals operates as follows. At the time interval of the service pause, formed by PAK 8, the formation of the signal of the general call to all subscribers. In this case, the blocks UPS CSP 3 and BPS CSP 4 generates a composite signal. In the subscriber’s radio station, convolution of a narrowband signal is carried out in the DSF block 18. According to the convolution signal at the output of the UPS PSP 3, matched filtering of the broadband signal is allowed in block 21, as a result of which the exact value in the block 22 of the clock signals that set the phase of the depacketator signals 24 is allocated. 25 and 28, a composite request response signal, similar in structure to the request signal. This signal is allocated in blocks 7 and 10 of the base station, setting in block 9 the exact time of the beginning of the formation of the response signal to the ith subscriber. At the same time, counter 5 calculates the propagation time of the radio signal to the i-th subscriber at the time of the arrival of the response signal of the i-th subscriber. The propagation time value can then be used to estimate the range of the i-th subscriber relative to the base station. Similarly, consecutive responses to the request of all subscribers of the communication system are allocated.

 In strict accordance with the moment of arrival of the i-th response signal, the base station sequentially generates to this subscriber a composite response signal in blocks 3 and 4, after highlighting the exact moment of receipt of which in the subscriber unit 23, the value of the message transmission pre-emption time is set by the subscriber in block 27, in according to which the time intervals PAK PRD 31 are then established.

 In the process of pre-emptive synchronization, the SHPS generator 13 of the base radio station generates a signal for a general request for synchronization to subscribers working in the same time channel. The request signal from subscribers is allocated in the block of correlators 32 and serves as a reference point for the exact time of the response to the request from subscribers. In accordance with the timing diagrams of FIG. 6 and 7, the subscribers sequentially generate responses to the request with their blocks of formation of SHPS 35, which are allocated at the base station by correlators 17 and specify in the block 11 the delay time of the signal. Also, in exact accordance with the time of reception of response signals, the base station generates response signals by block 13, which, when allocated in the blocks of correlators 32 of the subscribers, updates the block 30 of the delay time, which corrects the current value of the lead time of the emission of message signals from the subscribers in the blocks 29.

 Thus, it follows from what has been said that a synchronization system that provides synchronous and in-phase with reference copies of the base station PSP to bring PSP signals from different remote subscribers is feasible and allows you to build a multi-channel radio communication system with code division multiplexing on the basis of an SSN ensemble based on cyclic shifts of the bandwidth of one type .

 The introduced principles of equalizing the time intervals of message transmission for all subscribers of the communication system due to proactive synchronization and leveling of signal levels of subscribers by classifying them and then assigning the corresponding time channels significantly expand the class of orthogonal or close to orthogonal ensembles of signals suitable for working in such a communication system. In particular, it becomes possible to transmit messages from subscribers by signals strictly orthogonal only at discrete points, and not on the entire transmission time interval of a message element. Typical representatives of ensembles of signals orthogonal at a point are a system of orthogonal sinusoidal signals of the MCT type (multi-frequency telegraphy) and a binary discrete signal system based on Walsh functions.

 When using signals of the MCT type, each subscriber is assigned a sinusoidal signal as the address, the frequency of which is the value of one frequency from a set of address frequency values that are multiples of the frequency (average speed) of message transmission. The binary message of the subscriber modulates in phase (OFT or DOPT) a sinusoidal signal with a given value of the address frequency (subcarrier frequency). Next, the modulated signal is transferred to the common operating frequency band of the communication system using the reference radio frequency, which is the same for all subscribers of the communication system, for example, by the method of single-band modulation. The signals of all subscribers formed in the same way will be separable in the receiver of the base station if the necessary mutual phase relationships of the address subcarrier frequencies in the collective of subscribers remote at different distances from the base station are strictly maintained.

To assess the necessary accuracy of proactive synchronization of subscriber radio stations, which provides the binding of phases of subcarriers of the address frequencies of subscribers, consider the following example. Suppose that in a communication system with 5 time channels it is necessary to transmit messages at a speed of 2.4 kbps from each subscriber. The group transmission rate of each subscriber message will be 19.2 kbit / s (K _sr = 8). Then, for the implementation, for example, of the simultaneous operation of a group of 8 subscribers in one time channel through one base radio station, the necessary radio frequency band will be a value (19.2 kHz • 8) equal to 153.6 kHz. And in the 200 kHz frequency band 10 subscribers will be able to work simultaneously (19.2 kHz • 10 = 192 kHz). Given that similar groups of subscribers will be able to work in all 5 temporary channels, the total number of subscribers served by one base station will be 40 and 50, respectively.

 The highest frequency value of the address subcarrier of a sinusoidal signal in one subscriber group is 200 kHz. Accordingly, one period of oscillation of this signal is 5 μs, and the practical accuracy of maintaining the initial phase of the period of this oscillation is 5 - 10%, which is 0.25 - 0.5 μs. At the same time, the accuracy of estimating the propagation time of the radio signal between the subscribers' objects and the base radio station is determined by the signal base (≈1 / 4 of the DSS element duration) and will be 0.05 - 0.1 μs. And since the error in measuring the propagation time of the radio signal in turn determines the accuracy of the forward synchronization (initial setting of the phase of the addressable subcarrier frequencies), the indicated requirement for the accuracy of maintaining the initial phases of the address subcarrier frequencies of a group signal of the MCH type is fulfilled with a substantial (fivefold) margin. Based on the latter, the upper address frequency of the subcarrier signal can be increased 3–4 times in one group of subscribers, which is equivalent to an increase of 3–4 times the number of subscribers in the group. Instead of increasing the number of subscribers, it is possible to reduce the transmission speed of messages on subcarriers of addressable frequencies, if each subscriber is allocated more than one address frequency, but, for example, 4. Then, proceeding to the optimal MRI signals both in the system as a whole and for each subscriber, we come to 4.8 subcarrier frequency subcarrier manipulation. Indeed, 4.8 kbps • 4 = 19.2 kbps, which can be especially useful for multipath propagation of radio signals.

 All of the above will take place when using an ensemble of discrete binary signals in the form of Walsh functions that are also orthogonal at individual time points, and not over the entire time interval of transmission of message elements. As a sign of the address of the signal transmitted by the subscriber, each subscriber should be assigned a specific type of signal from the set of possible signals corresponding to the Walsh functions. The transmission of binary messages in this case will be carried out by transferring either a direct Walsh function or an inverse function to it. The Walsh functions in this case play the role of subcarriers of the address signals mentioned earlier in connection with the consideration of the ensemble of optimal frequency signals of the MCT type.

The equipment for the time-division channel separation of a base radio station that implements the proposed method is shown in FIG. 10 and 11. FIG. 10 illustrates the composition of the equipment of the transmitting part of the base radio station, which includes:
1 - subscriber signal distributor for temporary positions and code structure numbers;
2, 4, 6, 8, 12, 14, 16, 18 - random access memory (RAM);
3, 5, 7, 9, 11, 13, 15, 17, 19 — control schemes for writing and reading out RAM signals;
20, 21, 22 — message signal packetization units;
23, 24, 25 - schemes for combining temporary channels (signals) into a group signal;
26 - voltage shaper envelopes of temporary channels;
27 is a pseudo-random sequence signal generator (GNPSP) in the form of an M-sequence;
28 is a signal generator of a system of orthogonal functions such as binary Walsh functions or sinusoidal functions such as MCT;
29 - multi-tap shift register that implements a set of cyclic shifts of the SRP;
30, 32, 33 - modulators of the signals of the SRP (Walsh or MRT) by message signals;
31 is a linear adder signals of the code-time channels.

The listed blocks are interconnected as follows. The outputs of the signal sources of the messages of the subscribers are connected to the inputs of the distributor of the signals of the subscribers at temporary positions and numbers of code structures 1, the outputs of which are connected to the corresponding inputs of the signals of the messages of RAM 2, 4, 6, 8, 10, 12, 14, 16, 18, the outputs of which are in turn, connected to the inputs of the respective combining schemes of temporary channels 23, 24 and 25. To the other inputs of RAM 2, 4, 6, 8, 10, 12, 14, 16, 18 are connected the outputs of the respective control circuits of write and read addresses 3, 5, 7, 9, 11, 13, 15, 17, 19, the inputs of each of which are connected to one of odov stress envelope shaper 26 time channels, which are connected to the inputs of clock signals to the write pulse and the read RAM signal. United in this way, a group of RAM 2, 4, 6, control circuits 3, 5, 7 and a temporary channel combining circuit 23 form a signal packer of subscribers 20 messages. Accordingly, RAM 8, 10, 12, control circuits 9, 11, 13 and a circuit associations 24 form a signal signal packetization block 21, and RAM 14, 16, 18, their control circuits 15, 17, 19, and signal combination circuit 25 form a signal signal packetization block 22. Group signals of each packetizer 20, 21, 22 through respective association schemes 23 , 24, 25 go to one of the inputs, respectively, the modulator ov 30, 32, 33, with other inputs of which the outputs of the shift register 29 are connected, and the source of the reference sinusoidal generator with a frequency f _{о is} connected to the third inputs of the modulators 30, 32, 33. The outputs of each of the modulators are connected to the corresponding inputs of the linear adder 31, the output of which is then connected to the power amplifier of the groups of code-time signals. The input of the shift register 29 is connected to the output of the GNSSP 27. Instead of the outputs of the shift register 29, the corresponding outputs of the orthogonal signal generator of the MCT or Walsh can be connected to the inputs d, f, g of the modulators 30, 32, and 33.

The composition of the equipment and the connections of its main blocks, realizing the reception of messages in code-time channels at the base radio station, are shown in FIG. 11. The receiving part of the equipment of the base radio station contains:
1 - switching equipment of external communication channels;
2, 4, 6, 8, 10, 12, 14, 16, 18 - random access memory (RAM);
3, 5, 7, 9, 11, 13, 15, 17, 19 — control schemes for writing and reading out RAM signals;
20, 21, 22 - message signal depacketting units;
23 - voltage shaper envelopes of temporary channels;
24 - signal level meter;
25 is a pseudo-random sequence signal generator (GNPSP) in the form of an M-sequence;
26 - multi-tap shift register that implements a set of cyclic shifts of the SRP;
27, 28, 29 - blocks of correlation signal processing.

 The listed blocks are interconnected as follows. The information outputs of the switching equipment 1 are connected to external communication channels, for example, to channels of a public switched telephone exchange, and its control inputs, respectively, with the outputs of the control unit of the switching equipment. The information inputs of the switching equipment 1 are connected to the outputs of the depacketting units of the message signals 20, 21, 22, the first of which consists of RAM 2, 4, 6, respectively, the outputs of the control circuits 3, 5, 7 are connected to one of the inputs, and the other RAM inputs 2, 4, 6 are interconnected in parallel and connected to the output of the signal correlation processing unit 27, the first input of which through the first tap of the shift register 26 is connected to the output of the GNSS 25, the second input of the block 27 is connected to the output of the PSP clock generator, and the third input is correlation processing eye 27 connected to the output of the intermediate frequency signal path a receiving device. The inputs of the control circuits 3, 5, 7 are connected to the corresponding outputs of the voltage generator of the envelopes of the temporary channels 23. Another depacketator 21 consists of RAM 8, 10, 12 and control circuits 9, 11, 13, which are interconnected with the former 23 as described above 20. However, the parallelized inputs of the RAM 8, 10 and 12 are connected to the output of the signal correlation processing unit 28, the input of the reference copy of the SRP signal of which is connected to the output of the GNSS 25 through the tap 2 of shift register 26. The parallelized inputs of the RAM 14, 16, 18 of the last depacketator 22 are connected to the output of the correlator block 29, the input of the reference copy of the SRP of which is connected to GNPSP 25 through the tap 3 of shift register 26. The composition and all internal and external other connections of the depacketator 22 are also completely similar to those described previously for the depacketator 20. The input of the signal level meter 24 is connected to the output of the intermediate frequency (IF) signal path of the radio receiver, and the output of the meter 24 is connected to the input of the control unit of the base radio station.

 The equipment of the base station in the process of code-time channel separation works as follows. The subscriber message signal, for example, A1, is transmitted to the input of the distributor 1 in FIG. 11. Distributor 1 establishes a unique correspondence to the given subscriber number of the numbers of the temporary and code channels. In this example, it will be the 1st time and 1st code channel. In accordance with the foregoing, the continuous signal of the subscriber’s message A1 will be sent to the input of the packetizing unit 1, which compresses the continuous signal of the message into the packet of the 1st time channel using RAM 2, the control circuit 3, and the envelope former of the time channels 26. After combining in block 23 with 4 - with other packets (message signals of other 4 subscribers), a group signal containing 5 time channels is fed to a phase modulator 30, in which the bandwidth with the 1st cyclic shift number is modulated with this group signal. After linear addition with the output signals of other phase modulators containing group messages of other subscribers, but at the SRP with other numbers of cyclic shifts, the sum of the code-time signals is amplified in power and emitted in the common frequency band allocated for message transmission.

 When receiving signals from subscribers, also emitted in the common frequency band, at the base radio station, the sum of the subscribers' signals from the intermediate frequency path of the radio receiver simultaneously arrives at the inputs of all the correlation signal processing units 27, 28 and 29 shown in FIG. 11. In this case, in relation to the considered example, the message signal from subscriber A1 with the number of the cyclic shift of the memory bandwidth corresponding to the 1st will be selected at the output of the correlator block 27, the reference copy of the memory bandwidth in which also corresponds to the 1st number of the cyclic shift. The type of the selected signal is a message signal packet corresponding to the 1st time channel. The same value of the SRP cyclic shift number can be used (assigned) by other subscribers only in other time intervals (i.e., in other time channels 2-5). In the 1st time channel, simultaneously with message A1, messages can be transmitted from 2 other subscribers only to the SRP with cyclic shift numbers 2 and 3.

 The message packet of subscriber A1 from the output of the block of correlators 27 is fed to the input of the depacketator 20, in particular, to the input of RAM 2, the output of which is restored using the control circuit 3 and the envelope generator of time channels 23 to the initial continuous message from subscriber A1. A dedicated message through the switching equipment 1 can be sent to external communication channels, such as a city telephone exchange.

 In the service time slots of the timing diagram of the communication system of FIG. 6 and 7, the unit 24 measures the signal levels coming from subscribers. The measurement process is uniquely associated with the time of arrival of the response signal from each subscriber during the implementation of the proactive synchronization procedure described previously. In accordance with the results of measuring the signal levels of subscribers, their classification is carried out and the classification is periodically updated, followed by, if necessary, changing the assigned numbers of code-time channels as determined by the developed algorithm.

The transceiver equipment of the subscriber radio station is shown in FIG. 12. It contains:
1 - channel switch dedicated messages;
2 - channel switch for input messages;
3, 11 - shaper envelopes of temporary channels;
4, 12 - time channel switch;
5, 7, 13, 15 - schemes for managing write and read addresses of RAM signals;
6, 8, 14, 16 - random access memory (RAM);
9 - message depacketer;
10 - signal level meter;
17 is a signal combining circuit;
18 - block proactive synchronization of transmitted signals;
19 - pseudo-random sequence generator (GPSP);
20 - multi-tap shift register;
21 - modulator;
22 - switch signals synchronization;
23 is a diagram of narrowband synchronization of received signals;
24 - a comparator;
25 - discrete-matched filter;
26 is a clock tuning circuit;
27 - block correlation processing of broadband signals;
28 is a schematic diagram of the synchronization of the NPS;
29 - correlators;
30 - signal driver reference PSP;
31 - packer.

 Subscriber transceiver equipment operates as follows.

 The transmitted group signal of the base radio station from the output path of the IF of the receiver of the subscriber radio station is fed to the synchronization system of the received signals of the equipment for the time-division separation of channels implemented by blocks 23 and 27. In the process of extracting synchronization clocks, narrow-band PSP signals are processed sequentially using DSF in block 23 and synchronizing NI signals by circuit 28 in block 27. In accordance with the synchronization pulses of block 28, at the specified number of the code characteristic of the ШПС, block 30 (the number of the cyclic shift of ШПС) is allocated uppp signal of time channels in the correlators 29. The extracted signals of time channels, the sequence of which is determined by the shaper of temporary channels 3, synchronized by block 23, are sent to the switch of temporary channels 4. At a given number of the temporary channel inherent in this subscriber, the switch of temporary channels 4 will highlight the signals of temporary channels of this subscriber and will submit them to the depacketting unit 9, in which continuous signal signals from messages transmitted from the base radio station will be restored from signal packets and. Switch 1, depending on the specified messaging mode, will give the consumer either one duplex channel or two simplex channels.

 The signal level meter 10 evaluates the signal level received from the base station, by which the control unit of the subscriber station adjusts the level of the signal emitted by the subscriber station when transmitting messages to the base station.

The message signal transmitted by the subscriber station through the switch 2 (in simplex or duplex mode) is supplied to the continuous message packer 31, the signal packets from the outputs of which through the switch of numbers of the specified time channels 12 using the time channel shaper 11 occupy their temporary position in the group stream of time channels. The radiation prevention of signal packets is provided by the anticipatory synchronization system 18, which processes the narrow-band signals from the DSF 25 in block 23 and the signals from the synchronization circuit of the NPS 28 in block 27, as described previously. The forward synchronization system 18 corrects (refines) the initial start of the SRP cycle by the lead value 2τ in the generator 19, and then, after the address value of the cyclic shift number in the register 20 (ШПС addresses) is implemented, it is sent to the modulator 21. To the other input of the modulator 21 from the output of the combining circuit 17 signals received signal packets at predetermined time intervals, after which blending to PNS formed high memory bandwidth and the reference sinusoidal signal with a frequency f _o, a modulated message PNS converted, reinforcing etsya power and emitted to the communication channel.

 Thus, as follows from the above description, the proposed method allows to increase the number of subscribers served by the radio communication system, without increasing the group speed of the multi-channel signal, as required by the prototype method. This increases the efficiency of using the frequency band by reducing the value of the protective time intervals and it seems possible to work with optimal orthogonal signals in the subscriber group, which determines the potentially achievable throughput of the radio communication system.

Claims (1)

 A method of code-time channel separation in mobile radio communication systems based on the time separation of message transmission channels, wherein during transmission during the time separation of channels, continuous streams of signal messages of subscribers are compressed into periodic signal packets in accordance with the time diagram of the time channel separation, form a group stream of signal packets a message in which message signal packets alternate with guard time intervals and synchronization signal transmission intervals state, then, with message signal packets and clock signals, modulate the carrier frequency of the radio link and emit, and at the reception demodulate the radio signal, select the clock signals, in accordance with which the number of the required time channel is determined in the group stream of subscriber signal packets and the original continuous signal is restored from the message signal packets of the required time channel message, characterized in that in the time diagram of the communication system enter additional time intervals for measuring signal levels subscribers and the propagation time of the radio signal, in which the levels of the received signals of subscriber radio stations are measured at the radio base station, the measured values of the signal levels are compared with each other, the subscribers are combined into groups with similar signal level values, each group of subscribers with similar signal level values is assigned the same number time channel, and then the signals of subscriber groups of each time channel are further divided into code channels, and in the process of additional code p Separation of channels, each subscriber’s message signal packets are encoded with one of the signals of the ensemble of quasi-orthogonal type M-sequences or orthogonal signals such as Walsh functions or multi-frequency telegraphy (MCT), to ensure efficient separation of which in the common frequency band of receiving signals of a base radio station, subscriber radios emit signals with a lead in advance twice the propagation time of the radio signal to the base station relative to the received clock from the base station and, when received at the base radio station, the signals of subscriber radio stations are processed in accordance with the type of their coding signals, group signals of the temporary channels are extracted, and then the transmitted continuous message signal is restored from the signal packets of the desired time channel.

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