KR100860537B1 - Orthogonal code hopping multiplexing system employing switched beam array antenna - Google Patents

Abstract

The present invention relates to a method and apparatus for applying a fixed beam switched array antenna using a beamforming technique as an intelligent antenna in a forward link of a code division multiple access system using an orthogonal code hopping multiplexing scheme. The first communication station transmitter apparatus according to the present invention comprises a hopping pattern generator for generating an orthogonal code hopping pattern corresponding to a forward communication channel to each second communication station, and generating an orthogonal code to be assigned to each symbol period of the orthogonal code hopping pattern. An orthogonal code generation unit, a scrambling unit for generating a transmission signal by spreading the transmission symbol to each second communication station using the generated orthogonal code, and a fixed weight vector corresponding to a forward communication channel to each second communication station. And a fixed beam switching array antenna unit configured to generate and transmit a transmission signal whose transmission coefficient is set by the fixed weight vector to each of the second communication stations through a plurality of beamforming antennas. According to the present invention, by applying the spatial filtering provided by the fixed beam switching array antenna technique to the orthogonal code hopping multiplexing scheme, transmission quality degradation due to symbol collision and symbol puncturing can be effectively prevented.

Orthogonal code hopping multiplexing, fixed beam-switched array antenna, and inter-beam softener handoff.

Description

ORTHOGONAL CODE HOPPING MULTIPLEXING SYSTEM EMPLOYING SWITCHED BEAM ARRAY ANTENNA}

1A and 1B are block diagrams illustrating a Quadrature Phase Shift Keying (QPSK) spreading / despreading and modulation / demodulation unit of a conventional orthogonal code hopping multiplexing scheme.

FIG. 2 is a diagram illustrating a collision symbol control method when collision detection and collision between two different channels of a controller are detected in a conventional binary phase shift keying (BPSK) system of a conventional orthogonal code hopping multiplexing scheme.

3 is a block diagram illustrating a transmitter structure of a conventional fixed beam switched array antenna using phased array antennas, which is a type of intelligent antenna.

4 is a diagram illustrating operation of a conventional fixed beam switched array antenna to support mobility of a second communication station.

5 is a block diagram illustrating a baseband processing unit for each forward communication channel in a transmitter of an orthogonal code hopping multiplexing scheme according to the present invention to which a fixed beam switched array antenna is applied.

FIG. 6 is a graph illustrating that a beam reception state of a second communication station varies with time during transmission, which is determined through measurement of a beam-specific pilot signal.

7 is a diagram illustrating a fixed beam pattern formed through the positive beam switched array antenna.

8A and 8B illustrate a symbol collision tendency of a forward channel appearing in a second communication station as the second communication station is located in a non-overlapping beam region or an overlapping beam region in an orthogonal code hopping multiplexed fixed beam switched array antenna system. to be.

9A and 9B conceptually illustrate a random group level hopping pattern allocation scheme proposed by the present invention.

10A and 10B illustrate the operation of an embodiment of applying an inter-beam softener handoff to a fixed beam switched array antenna system of an orthogonal code hopping multiplexing scheme.

11A and 11B are graphs illustrating the transmission beam gain obtained at the beam angle of the beam area in which the second communication station is located as the second communication station moves.

12 is a conceptual diagram illustrating the process by which an additional forward softener handoff channel is established and released for a second communication station entering any beam overlapping region.

<Explanation of symbols for the main parts of the drawings>

130, 135: Spreader 146: Orthogonal Code Generator

540: jump pattern generator 542, 544: collision detection and controller

580: fixed weight vector allocator 810: first communication station

821, 822, 831, 832: second communication station

The present invention relates to wireless data transmission and reception of an orthogonal code hopping multiplexing scheme using a fixed beam switched array antenna. More particularly, the present invention relates to an orthogonal code hopping multiplexing scheme in a forward link of a mobile communication system of a code division multiple access scheme. Techniques and apparatus for applying a fixed beam switched array antenna using an array antenna and additional techniques and apparatus for mitigating the effects of intersymbol collisions and perforation based on the characteristics of the fixed beam switched array antenna in the applied technique and apparatus It is about the field.

Orthogonal Code Hopping Multiplexing (OCHM) is described in detail in Ref. 1 and Ref. 2, and in this specification, code division that is already commercialized and in service to help conceptual understanding of the multiplexing scheme. The following description is based on IS-95, which is a Code Division Multiple Access (CDMA) system.

The reference numerals used in the drawings for describing the prior art apply equally when the parts having the same function and structure are applied to the embodiments of the present invention.

1A and 1B illustrate a conventional Quadrature Phase Shift Keying (QPSK) spreading / despreading and modulation / demodulation unit of an orthogonal code hopping multiplexing scheme. In particular, FIG. 1A illustrates an internal configuration of a spreading and modulation unit of a first communication station transmitter. . Referring to FIG. 1A, symbols encoded by channels for each channel branch into an in-phase channel and a quadrature channel after QPSK modulation (110), and the signals "0" and "1" of each symbol. "&Quot; + 1 " and " -1 &quot;, which are physical signals actually transmitted through the signal conversion apparatuses 120 and 125, and are then spread by an orthogonal code (130 and 135).

The orthogonal code used at this time may be allocated differently for every symbol. One of the orthogonal codes generated by the orthogonal code generator 146 is selected and assigned to each symbol by the random leap pattern generated by the hop pattern generator 140. The orthogonal codes that are applied include not only Walsh codes, but also all orthogonal codes, such as the Orthogonal Variable Spreading Factor (OVSF) code or Orthogonal Gold code used in IMT-2000. .

Meanwhile, the collision detection and controllers 142 and 144 detect collisions between orthogonal code symbols due to random hopping patterns generated for each channel and perform appropriate processing. The collision detection and the outputs of the controllers 142 and 144 are output from the quadrature code generator 146 and multiplied by the signal passed through the signal conversion device 148 (132, 136), where symbol puncture due to intersymbol collision If necessary, it is "0", and in other cases, it is "1".

The symbols of each spread channel are amplified (150, 155) and then summed together (160, 165) with a power gain value determined by power control for each channel. QPSK spreading modulations 170 and 175 are performed by short Pseudo Noise sequences 172 and 176 through 174 and 178. The spread modulated signal passes through low pass filters 180 and 185, passes through carrier modulations 190, 195 and 200 that modulate to the transmission band for the IQ channel, and then sums up 210 (not shown). High power amplified through RF and then transmitted through the antenna.

FIG. 1B schematically illustrates the structure of a receiver of a second communication station corresponding to the first communication station transmitter described with reference to FIG. 1A. The signal received through the antenna is multiplied by the carrier signal (220, 225) and passed through the low pass filters 230, 235 to generate a baseband received signal. The PN columns 240 and 245 generated in synchronization with the PN sequence used for spread modulation at the transmitting side are summed in bit units with orthogonal codes generated from the hopping pattern generator 250 and the orthogonal code generator 252 synchronized with the transmitter. 254, 256, and then multiply the baseband received signal via signal conversion devices 258, 260 (262, 264). The baseband received signal, which has undergone the above process, is accumulated and despread during the transmission data symbol period (270, 275), and only the pilot channel component is extracted from the orthogonal code symbol assigned to the pilot channel to estimate the transmission channel (280). The phase distortion is corrected using the in phase distortion value (290).

FIG. 2 is a diagram illustrating collision between two different channels in a collision detection and controller of a BPSK orthogonal code hopping multiplexing system corresponding to the collision detection and controllers 142 and 144 in the QPSK scheme of FIG. 1A. If a collision is detected, it is a conceptual diagram illustrating a control method for a collision symbol.

Referring to FIG. 2, the same orthogonal code is used in any symbol interval by random leap with forward channels from the first communication station 210 to the second communication station a 221 and b 222 both active. In this case, the collision detection and controller compares the symbol code values on the forward channels of the two second communication stations a 221 and b 222. If the two symbol code values are the same, the symbols of the two second communication stations 221 and 222 are summed, resulting in an increase in symbol strength. This is called symbol synergy, and the controller output symbol value is "1". Becomes On the contrary, if the symbol code values of the two second communication stations 221 and 222 are different from each other, the symbol on the forward channel of the second communication station a 221 and b 222 is set to 0 as the controller output symbol value of each channel. It does not transmit, which is called symbol perforation. The purpose of symbol puncturing is to avoid error amplification of symbol estimation in the channel decoding process of the receiver, and the loss of transmit energy caused by arbitrary symbol puncturing may be compensated for by adjusting transmit power of another symbol. This control scheme for inter-symbol collision is applied to the collision detection and controllers 142 and 144 of FIG. 1A in the light of the fact that in the case of FIG. 1A, a branch operation is performed on the IQ channel for a complex signal after QPSK modulation. have.

FIG. 3 is a structural diagram for conceptually explaining a structure of a transmitter of a switched beam array antenna (SBAA) using phased array antennas, which is a type of intelligent antenna, according to the related art. Channel-received classification is performed according to the beam to which the second communication station belongs (310, 320, 330). These classified forward channels are signaled for each transmit antenna via respective fixed weight vector allocators 315, 325, 335 provided for phase allocation for each transmit antenna 370, 372, 374 to form the corresponding fixed beam. Branch to. Subsequently, when the fixed beam signals are added to each transmit antenna by the weight vector summer 340 and the transmit antenna signals are output, the output transmit antenna signals are carrier modulated (350, 352, 354) for each corresponding transmit antenna, and the radio unit Transmit antennas 370, 372, 374 via 360, 362, 364.

4 is a conceptual diagram illustrating each fixed beam pattern formed through the fixed beam switching array antenna and the operation of the present antenna to support mobility of a second communication station. The first communication station forms an arbitrary number of fixed beams according to the transmitter structure of FIG. 3, and transmits a forward channel for the corresponding two communication stations by using a beam pattern allocated to each second communication station, and assigns when the second communication station moves. The changed beam pattern is changed to a new beam pattern. This process is performed by updating the beam classification channel classifications 310, 320, 330 of FIG. 3 through higher layer control signals.

For example, at any point in time t_ref, any second communication station 420 is receiving a forward channel through the fixed beam A 431 and after a certain time t_1 has passed, the second communication station 420 When the position of the N-B moves to an area of the neighboring beam B 432, the first communication station 410 detects the pilot signal measurement information of the physical layer reported by the second communication station 420 and transmits the information through the higher layer control signal. The beam-specific group of the forward channel for the second communication station 420 is changed from A to B. Through this process, the beam pattern for the corresponding second communication station 420 is changed, which is called beam switching. In the fixed beam switched array antenna, since each beam formed is fixedly allocated, the mobility of each second communication station 420 is supported through the beam switching process.

In the case of using the fixed beam switched array antenna in the code division multiple access scheme, when the orthogonal codes are assigned to each forward link channel, the channel capacity provided by the reuse of a limited number of orthogonal codes for each beam may be increased. In this case, in general, a method of assigning a unique scrambling code for each beam may be used, and the beam-based scrambling codes used may have mutually orthogonal characteristics among different code strings in an arbitrary scrambling code, and different scrambling codes may be used. It has a level of cross-correlation between the code strings used. In practice, among the IMT-2000 system standards, the Quasi-Orthogonal Code of cdma2000 and the Multi-Scrambling Code of the Wideband Code Division Multiple Access (W-CDMA) system provide the above functions. There is a Kasami code. Due to the cross-correlation between the heterogeneous sets of codes, a near-far effect may occur due to the distance difference between the first communication station and the second communication stations in the beam overlap region, which is large reception at the correlator output of the receiver. It means that the interference energy appears.

(references)

Reference 1: Republic of Korea Patent Publication No. 2000-0029400

Reference 2: Korean Laid-Open Patent Publication No. 2004-0773635

In the orthogonal code hopping multiplexing scheme, by assigning a random hopping pattern for each channel, symbol collisions occur when symbols of a plurality of channels are spread to the same orthogonal code in an arbitrary symbol interval. In this case, as described above with reference to FIG. Similarly, a control method called symbol synergy / puncture method is applied to collision symbols. However, in the case of symbol synergy and symbol puncturing during the puncturing, the energy loss of the corresponding symbols is generated by turning off the transmission power of the collision symbols. When symbol puncturing occurs frequently due to collisions between user symbols, the symbol transmission energy loss caused by the symbol transmission energy deteriorates the decoding performance during channel decoding at the receiver and maintains the error rate of an arbitrary transmission frame. This increases the ratio of bit energy to noise energy (required received Eb / No).

The present invention relates to a fixed beam switched array antenna scheme in a situation where symbol collision between channels occurs in the orthogonal code hopping multiplexing scheme, which is a type of multiplexing scheme in a forward link of a mobile communication system using a code division multiple access scheme. Its purpose is to drastically reduce the occurrence of symbol collisions and perforations through the spatial filtering capabilities provided by it. This also mitigates signal quality deterioration in the radio section caused by inter-symbol collisions, thereby ultimately improving the quality of the received signal when the orthogonal code hopping multiplexing scheme is applied, and the user capacity in any first communication station region. The purpose is to simultaneously increase the channel capacity for a limited first station transmit power.

In order to achieve the above object, the present invention applies the spatial filtering function provided by the beamforming of the fixed beam switched array antenna to the spatial distribution of second communication stations that generate symbol collision in an orthogonal code hopping multiplexing scheme, As a result, it is characterized in that the occurrence of symbol puncture is reduced at source. In addition, the present invention reduces the degradation of channel decoding performance due to reuse of orthogonal codes and further enhances the performance by proposing additional techniques and apparatuses that further increase the performance of symbol collision and puncturing of the antenna scheme. have.

In addition, the present invention already considers that the fixed beam switched array antenna technology is a commercially available step, if the number of forward link communication channels provided through any fixed beam generated at the first communication station is less than the number of available orthogonal codes, By including a new hop pattern assignment scheme for allocating non-overlapping orthogonal code hopping patterns for each communication channel, an optimal link performance is maintained for any number of forward link communication channels.

Embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings for describing the embodiments of the present invention, the same reference numerals are applied to parts having the same structure and function as those included in the prior art drawings. The following description of the present invention focuses on the parts that need to be changed or added to the prior art.

5 illustrates an internal configuration of the baseband processing unit for each forward communication channel in the first communication station transmitter according to the present invention. Referring to FIG. 5, any user symbol branches (110) into an in-phase and quadrature-phase signal (110) and spreads for the orthogonal code via signal converters 120 and 125 ( 130, 135). The orthogonal code used in this case is designated by a beam-specific user channel hopping pattern generator 540 and an orthogonal code generator 146 that provide sign hopping patterns for channels belonging to individual fixed beams generated from the fixed beam switched array antenna. .

The symbol collision detection and controller 542, 544 detects whether there is a collision in symbol units by comparing orthogonal codes for each channel in any symbol interval of all forward link channels provided by the first communication station to a designated orthogonal code. For example, synergy or puncturing control may be performed by comparing symbol values between colliding symbols. If symbol collisions between any forward link communication channels are detected at the symbol collision detection and controllers 542 and 544, the target channels for which symbol collisions are detected are determined whether the received signal state of the receiving second communication station of that channel is beam non-overlapping. It is controlled in a different form depending on whether the beam overlaps.

If the receiving second communication station of the corresponding channel is in a beam non-overlapping state that receives a signal of an adjacent beam below an acceptable reception power threshold, whether a symbol of any forward channel collides is transmitted by the corresponding beam. The other channels are determined according to the existence of the same orthogonal code as the orthogonal code of the corresponding channel among the orthogonal codes used in the corresponding symbol interval. Meanwhile, when the receiving second communication station is in a beam overlap state in which not only a signal of a beam to which it belongs but also a signal of an adjacent beam is higher than or equal to a reference level value, all other channels transmitted by two overlapping beams are transmitted in the corresponding symbol period. Among the orthogonal codes to be used, it is determined according to the existence of the same orthogonal code as the orthogonal code of the corresponding channel.

The beam reception state of the second communication stations communicating with any first communication station is determined by the received signal analysis of each second communication station. For this purpose, the first communication station transmits a code string having a very small cross correlation for each beam as a pilot signal. do. Each second communication station detects the received signal strength of the corresponding beam from the received pilot signal for each beam to determine its own beam reception state, and periodically transmits the result to the first communication station to transmit the forward channel of the first communication station. It can be used for symbol collision detection and control in.

6 is a graph illustrating that the beam reception state of the second communication station varies with time by the above process. The received signal detection process of the second communication station is an ongoing process originally performed to support beam exchange for user mobility in the fixed beam switched array antenna, and does not require additional apparatus, cost, and complexity. The symbols spread by the symbol collision detection and the orthogonal code processed from the controllers 542 and 544 are respectively amplified (150, 1550) and then combined (560, 565) with other channels in any beam to which the channel belongs. QPSK spread modulation is performed by short PN sequences 172 and 176 for first communication station identification (170 and 175). The input symbols obtained through the above process are branched by each transmit array antenna to be allocated a phase in order to form a fixed transmission beam in the fixed weight vector allocator 580. The process after the fixed weight vector allocator 580 for each beam is performed in the same manner as the conventional method illustrated in FIG. 3. That is, after the fixed beam signals for each transmitting antenna are summed in the weight vector summer 340, the antennas 370 may be passed through the carrier modulation 350, 352, and 354 for each transmitting antenna and the radio units 360, 362, and 364. 372, 374.

When the fixed beam switched array antenna scheme is applied to the orthogonal code hopping multiplexing scheme, the spatial filtering function provided by the beamforming of the fixed beam switched array antenna generates a symbol collision in the orthogonal code hopping multiplexing scheme. Applied to the spatial distribution has the effect of reducing the occurrence of symbol collision and thereby symbol puncture.

FIG. 7 is a graph illustrating antenna gains of a fixed beam pattern formed through a fixed beam switching array antenna according to beam angles of respective fixed beams. Each fixed beam is configured to overlap with adjacent beams in a constant portion to mitigate the difference in transmit beam antenna gain depending on the position of the second communication station in the beam area. Accordingly, the beam area provided by the first communication station is a non-overlapping beam area in which a second communication station support area of an arbitrary fixed beam receives a signal of a beam to which the second communication station belongs at a considerably larger power ratio than the adjacent beam signals. A non-overlapping beam area (NOBA) and an overlapping beam area (OBA) for receiving the received power value of adjacent beam signals above a reference value are divided.

When the fixed beam switched array antenna is used for the orthogonal code hopping multiplexing scheme, the second communication station is located in the non-overlapping beam region and the overlapping beam region (ie, in the case of the beam non-overlapping state and the beam overlapping state). The symbol collision tendency of the forward channel for the second communication station appears different, an example for illustrating this conceptually is shown in FIGS. 8A and 8B.

8A is an example for explaining a symbol collision condition when an arbitrary second communication station a 821 is located in a non-overlapping beam region, and any second communication station a 821, b 822, c (823). In all reference symbol intervals t_ref for C), when the forward channels are all active and all hop to the same orthogonal code #i, the forward channels for the second communication station a 821 and the second communication station b 822 are the same beam. Since the symbol is transmitted through the symbol, the symbol transmitted by the first communication station 810 to the second communication station a 821 is received in a collision state with the transmission symbol to the second communication station b 822. However, since the forward channel symbols for the second communication station c 823 are transmitted through a beam different from the beam transmitting the symbols for the second communication station a 821, the forward channel symbols for the second communication station a 821 may be lost. 2 is received by the second communication station a 821 without being significantly affected by the transmission beam signal for the communication station c 823 so that no symbol collision occurs with the transmission channel of the second communication station c 823.

FIG. 8B is an example for describing a symbol collision condition when an arbitrary second communication station a 831 is located in an overlapping area of two neighboring beams, and as shown in FIG. 8A, a first communication method for the second communication station a 831 is illustrated. Since the transmission symbol of the communication station 810 is transmitted through the same orthogonal code i and the same beam as the transmission symbol for the second communication station b 832, the second communication station a 831 may be received with a collision between the symbols. In addition, since the second communication station a 831 is located in an overlapping area with a neighboring beam, the transmission symbol signal of the forward channel to the second communication station c 833 is also equivalent to the receiver of the second communication station a 831. As received in size, a collision with the transmission symbol of the second communication station c 833 also occurs.

Through the two examples above, the first communication station transmission symbol depends on the position (or second communication station reception state) of the corresponding second communication station in the beam generated when the fixed beam switched array antenna is applied to the orthogonal code hopping multiplexing scheme of the forward link. You can see the difference in the probability of collision.

Therefore, in applying the fixed beam switching array antenna technique to the orthogonal code hopping multiplexing scheme, unlike the conventional method of allocating a random hopping pattern of orthogonal codes through random number generation for each user channel, symbol code collision and puncturing are intentionally generated. A new orthogonal code hopping pattern generation technique can be applied.

9A and 9B illustrate a method for reducing symbol collision and symbol puncturing probability between users in an orthogonal code hopping multiplexing scheme according to the present invention, and using a random group-level codeword hopping-pattern allocation (RGHPA) scheme. This is an example conceptually. FIG. 9A illustrates a case where a beam-specific random group level hopping pattern allocation scheme is applied to various beams that appear when the transmission beam switching array antenna scheme of the first communication station is applied. When there are M forward link communication channels in any beam B and N _OC orthogonal codes can be used for the user communication channel, the random group level hopping pattern assignment scheme is M The four forward link communication channels are grouped in a collision-free hopping-pattern group (CFG) unit consisting of channels having a hopping pattern in which no symbol collision occurs. The number of collision avoidance jump patterns used in any beam changes as the number of user channels increases or decreases, specifically floor (M / N _OC ) +1. For reference, floor () means a floor function.

Because the number of user channels varies over time, the most recently created collision avoidance jump pattern group indicates that not all jump patterns in the group are assigned to the user channel, except that the number of user channels is an integer multiple of the number of group hop patterns. In view of this, it is separately defined as a recently-generated collision-free hopping-pattern group (LCFG). Also, in order to minimize and equalize symbol collision frequency of each channel with respect to the number of forward link user channels that change over time in an arbitrary beam, a hop pattern resetting process for each forward communication channel is introduced at a period above the frame level. Accordingly, the number of beam-free collision avoidance jump pattern groups and the jump pattern of individual channels change according to an arbitrary period of more than the frame level.

9B illustrates the operation of a per-group orthogonal leap pattern generator that generates unique leap patterns in which no symbol collisions between each other occur in any group of collision avoidance leap patterns. All collision avoidance jump pattern groups are assigned a unique random number sequence to define the hop characteristics of each collision suppression jump pattern group while sharing any N _OC mutual symbol collision free orthogonal code hop patterns. The collision avoidance jump pattern group performs a cyclic code sequence conversion bit by bit on the assigned unique random sequence with respect to the indicators of the common orthogonal code hopping patterns. The jump patterns of the collision avoidance jump pattern group generated by the above process have a property of not causing symbol collision because they maintain orthogonality with other jump patterns in the same group, and are random from existing orthogonal code jump patterns in other hop pattern groups. Random symbol collision is generated in the same way as the leap pattern allocation method.

The random group level hopping pattern allocation scheme is used for orthogonal code hopping multiplexing using a fixed beam switched array antenna to reduce the probability of symbol collision in an environment where the number of user channels required for each beam is smaller than that of the conventional random hopping pattern allocation scheme. Can be significantly lowered. In particular, in an environment where the number of forward link communication channels required per beam is less than the number of orthogonal codes, the existing communication channel is completely excluded by completely eliminating the probability that a symbol of any user channel in the beam collides with the symbols of other user channels in the same beam. It provides link performance equivalent to the code division multiplexing scheme in which a fixed orthogonal code is allocated (the maximum number of assignable user channels in this scheme is limited to the number of orthogonal codes).

In applying the fixed beam switched array antenna technique to the orthogonal code hopping multiplexing scheme, when a second communication station provided with a forward channel from any beam is located in an overlapping beam region within the entire beam region, not only the corresponding beam but also the signal of the adjacent beam is applied. Since the signal is received at a power level equal to or greater than a reference level, symbol collision may occur when other user channel symbols in a neighboring beam area use the same orthogonal code as that of the symbol of the corresponding channel. Accordingly, the puncturing probability, which is a result of symbol collision and control when an arbitrary second communication station is located in the overlapping beam area, is increased as compared to the case where it is located in the non-overlapping beam area. In addition, a roll-off effect of the transmission beam gain occurs in an overlapping beam region that exists on both sides of the beam pattern due to the transmission gain pattern of the beam when the actual beam is generated, resulting in deterioration of the link quality. .

The present invention proposes an inter-beam softer handoff scheme as a solution to alleviate the above two problems occurring for the second communication station located in the overlapping beam region. In the inter-beam softer handoff method, when an arbitrary second communication station is located in the overlapped beam area, an additional forward channel is allocated from an adjacent beam in addition to the forward link channel provided from the corresponding beam, and thus the second communication station is adjacent to the second beam station. A total of two forward channels are provided from the beams.

This method requires the system to be able to provide a large number of forward channels. The orthogonal code hopping multiplexing scheme of the present invention is compared with the conventional orthogonal code division multiplexing scheme in which the channel is limited as the number of orthogonal codes. Since there is no limit on the number of user channels (ie, hopping patterns for orthogonal codes) that can be provided at source and limited only to symbol collision or symbol puncturing probability, it is possible to provide a very large number of channels compared to orthogonal code division multiplexing. So it doesn't matter.

10A and 10B show that when applying a fixed beam switched array antenna technique to an orthogonal code hopping multiplexing scheme, when the user is located in an overlapping beam region, the inter-beam softener handoff may increase the symbol collision and puncturing probability for the user symbol. Conceptual example showing mitigation.

FIG. 10A shows at a symbol interval (n + 1) Ts when a second communication station a 1021 located in the beam overlap region is assigned each softener handoff channel from two adjacent beams via inter-beam softener handoff. Even if a puncturing occurs due to a symbol collision by selecting the same orthogonal code between the symbol of the forward channel originally assigned from the beam I and the forward channel symbol of the second communication station b1022 belonging to the beam II, the second communication station a from the beam II The other symbol assigned to 1021 indicates that the corresponding symbol is not completely lost and some symbol energy is received at the second communication station a 1021.

10B shows a symbol puncture when a second communication station a 1031 located in a beam overlapping region and a second communication station b 1032 generate a symbol puncture due to a collision between transmission symbols for each second communication station in an arbitrary symbol period. This indicates that some energy is transmitted to the receiving second communication station via another softener handoff channel of each second communication station rather than completely lost.

11A and 11B are graphs illustrating the transmission beam gain experienced by any second communication station according to the beam angle at which the second communication station is located when moving. FIG. 11A shows an example of the transmission beam gain according to the second communication station position when the inter-beam hard handoff is applied and FIG. 11B shows the combined transmission beam gain according to the second communication station position when the inter-beam softer handoff is applied. This example illustrates transmit antenna gain. As shown in FIG. 11B, any symbol at the second communication station receiver is additionally allocated by additionally allocating a forward channel through two adjacent beams to the second communication stations located in the beam overlap region via inter-beam softener handoff. In terms of the received symbol energy of the interval, the degradation of the beam antenna gain around the beam, which is a disadvantage of the conventional fixed beam switching array antenna, can be alleviated.

12 is an illustration of the process of establishing and releasing an additional forward softener handoff channel based on an inter-beam softener handoff scheme for a second communication station entering any beam overlapping region. Any second communication station a receives a pilot signal transmitted from neighboring beams other than the beam in the currently located area and measures the received power intensity value for each beam. If the measured received power intensity value of the beam II is equal to or greater than the acceptable reception power threshold, the second communication station a recognizes that it is located in the beam overlap region and simultaneously sets the inter-beam softener handoff. Enters the inter-beam softer handoff set ready mode and informs the first communication station via beam I of the information needed to set the softer handoff channel to the neighboring beam II. Then, when the received power strength value of the beam II is equal to or more than the softer handoff channel addition threshold, the second communication station a informs the first communication station of the information through the beam I through the beam I and the beam. An additional forward softener handoff channel via II is assigned.

Then, when the received power intensity value at the second communication station a for the beam I gradually decreases to be below the allowable received power threshold, the second communication station a recognizes that it is located in the beam non-overlapping area and at the same time, the inter-beam softener Enter the inter-beam softer handoff release ready mode to inform the first station of the situation information. If the received power strength value at the second communication station a for beam I decreases to be below the softer handoff channel dropping threshold, then the first communication station is informed of this information and the soap from beam I Release handoff channel.

In carrying out the above process, the purpose of using two softener handoff channel addition / exclusion thresholds in addition to the conventional allowable received power threshold is that unspecified reception power strength due to fading when only the allowable received power threshold is used. This is to prevent the frequent repetition of the inter-beam softener handoff setting and exclusion due to one variation, and to guarantee the processing time required for setting and releasing the forward channel by the inter-beam softener handoff.

In the code division multiplexing scheme, the orthogonal code can be reused for each beam by applying a fixed beam switching array antenna. However, in this case, the state of the orthogonal code in the newly entered beam is monitored during the beam exchange when necessary for the movement of the second communication station. If necessary, the reassignment of orthogonal codes should be carried out for each second communication station, which may increase the required system load and complexity. In addition, if an error or delay occurs in the reassignment process, the corresponding second communication station channel may be unable to communicate due to a continuous frame error due to continuous interference from the same fixed orthogonal coded user channel. Furthermore, if the orthogonal code used for the forward channel for any second communication station located in an area where artificial inter-beam overlap is used in a neighboring beam, this problem is avoided because it is already subject to significant interference before the beam exchange process begins. In order to solve this problem, it is necessary to reassign orthogonal codes based on individual user positions or to perform scrambling using unique code strings for each beam. Considering the relatively large overlapping area between beams in the switching array antenna, a large system load and complexity are required, and in the near-far effect, considering that the scrambling code strings used for scrambling between beams have a mutual correlation. There is a possibility that the influence of the inter-beam interference caused by .

In contrast, applying a fixed beam switched array antenna, PN random number of the new collision avoidance jump pattern group to the existing beam switched signaling without the need to monitor the use jump pattern in the newly entering beam when switching the beam of any second communication station. It is enough to pass an offset of. In addition, even if an error or delay of a new hop pattern assignment occurs, the second communication station channel is more robust than the conventional code division multiplexing scheme because it experiences random symbol collisions with other channels of the newly entering beam at random probability. Has performance.

In addition, according to the orthogonal code hopping multiplexing scheme using the fixed beam switched array antenna technique, when a user is located in the beam overlap region, instead of receiving continuous interference from adjacent beam signals, the symbol collision probability is increased. do. This avoids large system loads, increased complexity or interference caused by the use of special orthogonal code reassignment or interbeam scrambling techniques, but rather on the basis of the large number of user channels that orthogonal code hopping multiplexing can provide. It is possible to take the link gain and reduce the impact of symbol collision through off or selective interbeam hopping channel allocation techniques.

According to the present invention, spatial filtering is performed to alleviate the degradation of link quality due to symbol puncture due to inter-symbol collision caused by random orthogonal code hopping patterns in the forward channel transmission in the conventional orthogonal code hopping multiplexing scheme. By applying a fixed beam switched array antenna that provides a function to an orthogonal code hopping multiplexing scheme, the frequency of symbol punctures for any user load is significantly reduced compared to the case of using a basic omni-directional antenna or a sector-divided antenna. .

In addition, by applying the proposed random group level hopping pattern allocation scheme for each beam, each second communication station may be configured when the number of forward link communication channels provided to the second communication stations belonging to each beam is less than or equal to the number of available orthogonal codes. Depending on whether they are located in the beam non-overlapping region or the beam overlapping region, the frequency of the symbol is either completely excluded or significantly lowered so that there is no effect on the link performance, resulting in link quality equivalent to orthogonal code division multiplexing.

In addition, even if the number of forward channels provided by the first communication station exceeds the number of available orthogonal codes, the frequency of symbol collisions can be significantly lowered than in the case of using a random hopping pattern in the conventional orthogonal code hopping multiplexing scheme. By employing the inter-beam softener handoff scheme, the high symbol puncturing probability problem of the second communication stations in the beam overlap region caused by artificially superimposing the fixed beams in use of the fixed beam switched array antenna can be alleviated.

In terms of a fixed beam switched array antenna, the conventional orthogonal code division multiplexing scheme assigns orthogonal codes to the forward link communication channel for each second station stationarily and reuses orthogonal codes for each beam according to the position of the second station. Since continuous interference may occur in the corresponding forward channel, a dynamic orthogonal code allocation method based on the orthogonal code usage status of all adjacent beams is required, which increases the complexity and cost of the system. In order to solve the above problem, a scrambling code having a low cross-correlation can be allocated for each beam. This method has a problem that can continuously cause large interference due to a source phenomenon from a second communication station receiving a forward link communication channel. have. In contrast, the present invention is defined as a symbol collision in which the influence of interference on the reception of the corresponding forward link communication channel according to the position of the second communication station by leaping the orthogonal code in symbol units is defined within the symbol period, and thus the degradation of the link quality. By applying the schemes proposed in the present invention to the generation of symbol puncturing that causes a significant reduction in the frequency, a high channel encoding / decoding gain is obtained, resulting in system complexity and processing load imposed on the coping and beam exchange processes in the beam overlapping region. Can be greatly reduced.

Claims (23)

A transmitter apparatus of a first communication station for providing a beam area to at least one second communication station and transmitting data through a forward communication channel to a second communication station located in the beam area, A hop pattern generator for generating an orthogonal code hopping pattern corresponding to a forward communication channel to each of the second communication stations; An orthogonal code generation unit generating an orthogonal code to be allocated to each symbol section of the orthogonal code hopping pattern; A scrambling unit for spreading a transmission symbol to each second communication station by using the generated orthogonal code to generate a transmission signal; And A fixed weight vector corresponding to a forward communication channel to each second communication station, and transmitting the transmission signal whose transmission coefficient is set by the fixed weight vector to each second communication station through a plurality of beamforming antennas; Beam Exchange Array Antenna Transmitter device comprising a. The method of claim 1, Comparing each symbol section of a separate orthogonal code hopping pattern respectively corresponding to a separate second communication station, detecting when the orthogonal codes of the separate orthogonal code hopping pattern match in a specific symbol period (hereinafter, "symbol collision") A symbol collision detection unit; And A symbol collision control unit that adjusts a transmission symbol value to the second separate communication station according to whether the transmission symbol value to the second second communication station is the same when the discrimination collision is detected; Transmitter device further comprising. The method of claim 2, And the symbol collision control unit adjusts the value of each transmission symbol to '0' when the transmission symbols to the second separate communication station are different. The method of claim 2, The symbol collision detection unit may receive information on whether each second communication station is located in an inter-beam overlapping area or a non-overlapping area from each of the second communication stations, and detect symbol collision by referring to the received position information. Transmitter device. The method of claim 4, wherein The symbol collision detection unit may further refer to a comparison result with an orthogonal code included in a hopping pattern of another communication channel transmitted through a neighboring beam when each of the second communication stations is located in an overlapping area between beams. Transmitter device. The method of claim 4, wherein And the position information received from each of the second communication stations is information determined based on the received power intensity value of the pilot signal for each beam periodically measured by each of the second communication stations. The method of claim 1, And the plurality of beam regions provided by the fixed beam switching array antenna unit includes a region partially overlapping neighboring beams. The method of claim 7, wherein And the fixed beam switched array antenna unit further allocates a softer handoff channel to a second communication station located in the overlapping area. The method of claim 1, The hopping pattern generator generates at least one collision avoidance group by grouping all the generated hopping patterns into units of a plurality of hopping patterns in which no symbol collision occurs, and forward communication channels to a second communication station belonging to the same beam area. And preferentially allocating a hopping pattern included in the same collision avoidance group for. The method of claim 9, When the number of second communication stations belonging to a specific beam area exceeds the total number of jump patterns included in the collision avoidance group, the hop pattern generating unit may collide another collision with respect to the forward communication channel to the second communication station corresponding to the excess. And assigning a jump pattern included in the exclusion group. The method of claim 9, And the hopping pattern generation unit adaptively changes the number of the collision avoidance groups according to the total number of forward channels measured in a period equal to or greater than a frame period with respect to the beam. The method of claim 1, And the hopping pattern generator separately assigns a forward communication channel to a second communication station belonging to a different beam area. The method of claim 1, And the orthogonal code generation unit shares an orthogonal code set for modulating symbols transmitted to a second communication station belonging to a different beam area. A second communication station receiver apparatus, which is located in a beam area provided by a first communication station and receives a symbol signal spread by a plurality of orthogonal codes that hop in a predetermined pattern from the first communication station, Determining whether one of the plurality of beam areas provided by the first communication station is located in a non-overlapping area or an overlapping area between neighboring beams, and transmitting information on the location to the first communication station. Receiver device. The method of claim 14, And the receiver device determines whether it is located in the non-overlapping area or the overlapping area based on the received power strength of the pilot signal received from the first communication station. The method of claim 15, And the receiver device determines that the receiver device is located in the overlapping area when the received power intensity exceeds an allowable reception power threshold. The method of claim 14, And the receiver device detects a symbol transmitted from the first communication station via a forward communication channel and an additional softener handoff channel assigned to the second communication station when the second communication station is located in an overlapping area. Receiver device. Generating an orthogonal code hopping pattern corresponding to each of the second communication stations located in the beam area provided by the first communication station and an orthogonal code for each symbol section of the hopping pattern; Generating a symbol signal to be transmitted by spreading a symbol to be transmitted to the second communication station using the generated orthogonal code; And Transmitting the symbol signal to the second communication station via a fixed beam switched array antenna Data communication method comprising a. The method of claim 18, It is determined whether the second communication station is located in any of the non-overlapping areas of the plurality of beam areas provided by the first communication station or in an overlapping area between neighboring beams, and the determined position information is determined by the first communication station. Transmitting to; And The first communication station receiving the location information and allocating an additional softener handoff channel for symbol transmission to the second communication station when the second communication station is located in an overlapping area; Data communication method further comprises. The method of claim 19, The determining of whether the information is located in the non-overlapping area or the overlapping area may include determining whether the location is based on the received power intensity value of the pilot signal received from the first communication station at the second communication station. Way. The method of claim 19, Allocating the additional softer handoff channel may include: Establishing the additional softer handoff channel when the second communication station enters an overlapping area from a non-overlapping area; And Releasing the additional softer handoff channel when the second communication station advances from the overlapping area to the non-overlapping area; Data communication method comprising a. The method of claim 21, And preparing for setting or releasing prior to setting or releasing the additional softener handoff channel, and performing the setting or releasing step after entering the preparation step. A computer-readable recording medium having stored therein program code for performing a data communication method according to any one of claims 18 to 22.

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