MXPA98001619A - Method and system to process a plurality of multi access transfers - Google Patents

Abstract

A method and system incorporating the use of interference cancellation during the packaged portion of a wireless telecommunications system is described. A subscriber unit of the wireless telephone system 104 receives multiple forward link signals 102 and estimates the data that is transmitted through each forward link signal 102. In response to these estimates, an ideal waveform 309 is calculated. each forward link signal 102, the ideal waveforms associated with the other forward link signals are subtracted from the current energy level of that forward link signal before the data to be transmitted is determined. In the preferred embodiment, the forward link signals are processed in accordance with the techniques of the spread spectrum of multiple access by division of code, and the estimation of the data that is being transmitted is carried out through the use of a transformer Fast Hadamard 308. In an alternative modality, the estimation of the data is carried out in a single channel, or sub-set of channels, carried by the forward link signals, estimating at least the level of the associated signal of a pillar channel

Description

METHOD AND SYSTEM. TO PROCESS A PLURALITY OF MULTIPLE ACCESS TRANSMISSIONS BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates to wireless communications. More particularly, the present invention relates to a method and system that incorporates the use of interference cancellation during the forward link portion of a communication of the wireless telecommunications system. II. Description of the Related Art Figure 1 is an illustration of the radio frequency (RF) electromagnetic signal transmissions associated with the forward link portion of a code division multiple access wireless (CDMA) telecommunications system. The stations of the base transceiver 100 (a) and (b) transmit forward link signals of the multiple access broadcast spectrum 102 (a) and (b) which overconvert to an RF bandwidth. Through the reflection process, the construction 106 generates a forward link signal 102 (c) in response to the forward link signal 102 (a). The unit of the subscriber 10 (a) is positioned in such a way that it receives the forward link signals 100 (a), (b), and (c), while the subscriber unit 104 (b) is placed in such a way that it only receives the forward link signals 102 (a) and (b). In an alternative configuration, one or more stations of the base transceiver 100 generates multiple forward link signals 102 which are transmitted to the portions of the neighboring area, usually referred to as "sectors", through the directional antenna systems. Each forward link signal 102 comprises a set of channels, each of which carries a kind of information necessary to drive the forward link portion of any communication (typically a telephone call) to the subscriber units 10 (a) and (b) The various kinds of information include pilot data for detecting the presence of a forward link signal 102, synchronization data for synchronization with the forward link signal 102, paging data for notifying the subscriber unit 104 of an incoming communication , and various sets of traffic data, which generally consist of digital audio information, digital data, or both. The digital audio information is usually an electronic representation of the physical sound waves associated with the current audio information, preferably generated through the process of adjusting the voltage level of a node within a telephone or other electronic system based on the samples of the sound wave. The electronic information is digitized by carrying out a periodic sampling of that voltage, and by generating binary numbers corresponding to the voltage potential detected in each sample. Various techniques for encoding and compressing these binary numbers can also be employed as is well known in the art. At the reception of each forward link signal 102, the subscriber units 10 (a), (b) separate the channels they need for their particular communication from the remaining channels through various types of signal processing. The remaining channels contain the information used to conduct other communications with other subscriber units 104 in the same area (not shown), which are also carried by each forward link signal 102. The generation of the set of channels necessary to transmit the multiple Information classes through a single forward link signal 102 is carried out through the use of a set of channel codes, each of which is orthogonal to the remaining set. Prior to transmission, each bit of data associated with each class of information is modulated in direct sequence in a synchronized manner with one of the channel codes from the code set of the channel. In an implementation of such a system, sixty-four channel code are used, each channel code containing sixty-four platelets, each platelet having a value either of 1 or -1, with a -1 being used to represent a logic 1 and a 1 representing a logic 0. Once modulated, the various types of data are disseminated through direct sequence modulation with a common diffusion code, but which also comprises a series of values 1 and -1. The broadcast code is generally much larger than the channel codes and only a portion of it is applied to any particular data bit. The broadcast data are then summed together and overconverted for transmission through the forward link signals 102. As shown in Figure 1, the multiple instances of these forward link signals are generated either separately in the stations of the base 100 transceiver, or through the reflection process. Each of the forward link signals can then be received by the subscriber units 10 (a) and (b). In the reception of a set of multiple feed link signals 102, the subscriber units 104 (a) and (b) de-diffuse and demodulate a subset of these forward link signals in order to separate the data necessary to drive a communication. The subset is selected based on the signal quality and, in which the forward link signals 102 promote the diversity of signal sources. If less than a certain number of forward link signals 102 are received, all forward link signals 102 can be demodulated. The demodulation is carried out with a particular channel code from the set of orthogonal channel codes that has been assigned to the desired data. The demodulation of the forward link signal 102 with a particular channel code removes another orthogonal energy from that forward link signal 102, thus isolating the desired data associated with that channel code from the remaining data since the set of channels within each forward link signal remains synchronized. Figure 2 is a block diagram of the RF signal reception and the processing portion of a subscriber unit 104 (FIG 1) when configured according to the prior art. During operation, any RF signal received by the antenna system 202 having frequencies falling within a predetermined bandwidth is subverted by the RF signal processing system 203 and supplied to the AGC 200 system. The AGC system 200 measures the energy level of the subverted signals and amplifies or attenuates them as necessary to place the energy level of those signals within a predetermined decibel range. The adjusted gain signals are then applied to the analog signal processing system 201, which also subverts and digitalizes the signals, and applies the digitized signals to the scanner 206. The scanner 206 receives the digitized signals and identifies any forward link signal 102 transmitted from the base transceiver station 100 when searching the associated pilot channel for several time shifts. When a forward link signal is detected 102, the browser 206 calculates a time of arrival for that forward link signal 102, which in the preferred embodiment takes the form of a time offset from a synchronization signal, and provides that information to the control system 205 The control system 205 then allocates one of the de-diffusers 208 (a) - (c) to de-diffuse the forward link signal 102 using the time offset. Diffusion is generally carried out through direct sequence demodulation, which, in one implementation, constitutes carrying out a platelet multiplication operation per platelet in the data using the same diffusion code originally used to disseminate the data . As additional forward link signals 102 are detected, the control system 205 identifies those of the highest quality and assigns the de-diffusers 208 (a) - (c) to de-diffuse those signals. The resulting de-diffused signals from the de-diffusers 208 (a) - (c) are passed to the demodulators of the traffic channel 210 (a) - (c), which demodulate the signal using a channel code associated with the traffic data desired, with the appropriate channel code being unique to each subscriber unit 104 engaged in a communication with a particular base transceiver station 100. In an implementation of such a system, the demodulation with the channel code comprises performing an operation of platelet multiplication per platelet with the data using the code of the complete channel and then add the multiplication results to obtain an estimate of the data that is transmitted. The estimates from the demodulators of the traffic channel 210 (a) - (c) can then be received from the nodes 212 (a) - (c) by other signal processing systems within a subscriber unit 100 (not shown) ), which will generally combine the estimates using various well-known techniques in order to generate a single estimate of the data used for the additional processing. During the processing of a particular forward link signal 102, the channels within that forward link signal 102 remain synchronized as they are transmitted through a single RF signal, and therefore go through the same path to arrive to a particular destination such as the subscriber unit 104. This is not the case of the channels carried by different forward link signals 102, however, since the different forward link signals 102 generally go through different paths and therefore so many different distances to reach a particular destination. These different distances cause each forward link signal 102 to arrive with a slight time offset with respect to other forward link signals 102, which remove any orthogonality between the channels carried by a forward link signal 102 with respect to the channels carried by another forward link signal 102. This lack of orthogonality prevents the energy associated with the channels of a first forward link signal 102 from being completely removed from a second forward link signal 102 through demodulation with a channel code. Although the presence of this undistorted energy degrades the quality of any data produced using the second forward link signal 102, the degradation is generally not of a sufficient degree to prevent the proper operation of the wireless telephone system.

However, if a method could be developed to process a forward link signal that allows at least some of the non-orthogonal energy from other forward link signal 102 to be removed, such development would substantially improve the quality of the data produced. by a subscriber unit 104 that incorporates the use of that method. This improved quality would also result in a reduction in the amount of energy needed to complete the data transmission, which, in the context of a CDMA wireless telecommunications system, allows the increase of the data transport capacity. Therefore, such development would be highly desirable. SUMMARY OF THE INVENTION Based on the foregoing, a method and system for incorporating the use of interference cancellation during the forward link portion of a wireless telecommunications system is described. A unit of the wireless subscriber receives multi-feed link signals and estimates the data that is transmitted through each forward link signal. In response to these estimates, an associated ideal waveform is generated for each received forward link signal. For each processed forward link signal, the ideal waveform of the other forward link signals is subtracted from the level of the signal of that forward link signal being processed, before the transported data is determined. In the preferred embodiment, the forward link signals are processed in accordance with the techniques of the broadcast multiple code access broadcast spectrum, and the estimation of the data that is transmitted is carried out through the use of a power transformer. Hadamard fast. In an alternative embodiment, the estimation of the data is carried out in a single channel, or sub-set of channels, carried by the forward link signals, estimating at least the level of the signal associated with a pilot channel. BRIEF DESCRIPTION OF THE DRAWINGS The features, objectives, and advantages of the present invention will be more apparent from the detailed description set forth below when taken in conjunction with the drawings, in which like reference characters are correspondingly identified throughout. and where: Figure 1 is a diagram illustrating a radio frequency (RF) transmission associated with the forward link portion of a wireless telecommunications system; Figure 2 is a block diagram of the reception of the RF signal and the processing portion of a subscriber unit when configured according to the prior art; and Figure 3 is a block diagram of the reception of the RF signal and the processing portion of a subscriber unit when configured in accordance with an embodiment of the invention. DETAILED DESCRIPTION OF THE PREFERRED MODALITY A method and system for incorporating the use of interference cancellation during the forward link portion of a wireless telecommunications system is described. In the following description, various signal processing systems and the installations thereof are described in detail. It will be apparent to one skilled in the art that a variety of well-known methods and apparatus for implementing such signal processing systems can be used including the use of digital signal processors and digital microprocessors controlled by the software, or integrated circuits designed to the measure, being the last ones used in the preferred modality. It will also be apparent to an expert in the field that where multiple instances of a particular system are shown, a single case of that system can generally be substituted, the use of that time-sharing system being among the various functions carried out by the multiple systems. In other cases throughout the application, various well-known systems are described in the form of blocks. This is done in order to avoid unnecessarily confusion of the disclosure of the present invention. In general, the signal levels and the data referred to throughout the application constitute electronic representations, dependent on the voltage of various types of digital information including the audio information generated through sampling, or of voltages generated for the purpose of controlling other electronic systems. Although the invention is described in the context of a land-based wireless cellular telephone system, other wireless communication systems will benefit from the use of the present invention including satellite-based wireless telecommunications systems. Figure 3 is a block diagram of the reception of the radio frequency (RF) signal and the processing of the portion of a subscriber unit when configured in accordance with an embodiment of the invention. The RF signal processing system 303 is coupled to the antenna system 302 and the automatic gain control system (AGC) 300. The analog signal processing system 301 is coupled to the AGC 300 system as well as the 306 de-diffusers ( a) - (c), and the scanner 304. The control system 305 is coupled to the scanner 304. The output of the de-diffusers 306 (a) - (c) is applied to the fast Hadamard transformation systems (FHT) 308 (a) - (c) and the delay circuits 311 (a) - (c). the output of the delay circuits 310 (a) - (c) passes through the subtraction systems 312 (a) - (c) and the traffic channel demodulators 310 (a) - (c) respectively, before applied to combiner 314. The outputs of the FHT systems 308 (a) - (b) apply to the addition and estimation systems (S & E) 309 (a) - (c). The subtraction system 312 (a) receives the outputs of the S & amp; E 308 (b) - (c), the subtraction system 312 (b) receives the outputs of the S & E 308 (a) and (c), and the subtraction system 312 (c) receives the outputs of the S & E 308 (a) and (b). In addition to the connections shown there are also additional connections between the control system 305, the traffic channel demodulators 310, and the FHT 308 systems, the preferred method of connection being the use of a control bus, to which it is coupled each system. These connections are not shown to facilitate drawing, but are used to exchange control information between the various systems. Additionally, although only three examples of 306 de-spreaders are shown, FHT 308 systems, S &amp systems; E 309, subtraction and traffic systems 312, other embodiments of the invention may include the use of a higher or lower number of these signal processing systems. As mentioned above, part of the use of some systems may be timeshare . It should also be noted that the use of these circuit assemblies does not need to equal the number of traffic channel demodulators 310. In general, any of the S & E 309 should have its outputs applied to each subtraction system 312 associated with a different traffic channel demodulator 310. Other embodiments of the invention may apply fewer outputs applied to each subtraction system 312, however, such a configuration would probably be the result of hardware constraints, not performance considerations, and therefore not preferred. During operation, the RF signals received by the antenna system 302 having frequencies that fall within a predetermined bandwidth are subverted by the signal processing system 303 and apply to the AGC 300 system. The AGC 300 system locates the signals in a predetermined decibel range and applies the adjusted signals to the analog signal processing system 301. The analog signal processing system 301 it also subverts the signals to baseband and digitizes the baseband signals using or It then displays the bit samples, and applies the digitized signals to the scanner 304 and the de-diffusers 306 (a) - (c). The scanner 304 detects any of the forward link signals 102 (fig 1) received within the digitized signals by performing the correlations using a pilot channel code and a predetermined set of pilot data at various time shifts until it is detects an increased energy level. Additionally, the browser 304 identifies the base transceiver station, from which the forward link signal is generated. Additionally, the scanner 304 measures the signal strength of each forward link signal 102. This information is provided to the control system 305. The control system 305 configures each of the 306 (a) - (c) decoders. ) to properly de-diffuse the forward link signals 102 identified by providing each de-diffuser with the time offset information associated with one of the forward link signals 102 detected by the browser 304. In the preferred embodiment, the de-diffusion is carried out by multiplying the digitized signal with the broadcast code used to originally broadcast the data. The control system 305 also provides the associated traffic channel demodulators 310 with the appropriate traffic channel code, which will depend on the base transceiver station, from which the forward link signal is generated. In the preferred embodiment of the invention, each channel code is comprised of sixty-four platelets that have either a value of 1 or -1 representing a logic 0 and 1 respectively, and each data bit is modulated using the code of full channel. Sixty-four channel codes are also used in the preferred embodiment, each of which is orthogonal to the remaining set. Such a code set! it is frequently referred to as a Hadamard matrix, with each row within the Hadamard matrix constituting a channel code, and with the channel codes being referred to as "alsh" codes or sequences. The FHT 308 (a) - (c) systems receive the de-diffused data from the 306 (a) - (c) de-diffusers and perform a fast Hadamard transformation on the de-diffused data generated from the de-diffusers 306 (a ) - (c). The fast Hadamard transformation is essentially the multiplication of the data matrix with a Hadamard matrix using one of a set of fast algorithms to carry out such an operation well known in the art. A normal matrix multiplication can also be carried out, however, such an operation will not be as efficient as a fast Hadamard transformation. The Hadamard matrix is comprised of the set of sixty-four channel codes used to modulate the various types of data and to define the various channels, and the result is the multiplication of each channel code by the de-diffused data, and the addition of all products that result from the multiplications associated with a particular channel code. The fast hadamard transformation produces a set of values representing the estimated signal or voltage levels transmitted through the corresponding set of channel codes used to generate the associated forward link signal 102 (fig 1). Each voltage level provides an estimate of the data transmitted through the corresponding channel, as well as the energy level of the associated forward link signal 102. The S &amp systems; E 309 (a) - (c) receive the set of estimates and calculate a corresponding ideal waveform for each channel. The shape of each wave corresponds to the direct sequence of the estimated data value modulated by the corresponding channel code. Various methods for carrying out the ideal waveform generation operation including the application of the estimated data set for another FHT 308 system, or the use of a look-up table, which stores the data, will be apparent to one skilled in the art. the set of waveforms available for each channel and which selects the appropriate waveforms for each channel based on the corresponding data estimate. These waveforms are then adjusted based on the energy levels of the associated forward link signal, an estimate of which is also generated by the FHT 308 systems as described above and summed together. The adjustment of the energy level can be done at another time, in the processing it is an alternative embodiment of the invention, which is included before the wave forms are added. The S & E 309 then apply to the value of the resulting summed waveforms, to associated subtraction systems 312, with the other forward link signals 102 being processed. Each subtraction system 312 (a) - (c) subtracts the summed waveforms, supplied by the S & E 309 from the signals coming from the corresponding delay circuits 311 (a) - (c). The 311 delay circuits provide sufficient delay to allow the FHT 308 systems and the S & E carry out their various functions, and may be comprised of any type of storage system or data memory. The delay allows the waveforms calculated by the S & E 309 are subtracted from the appropriate portion of the forward link signal 102 that is processed. The resulting signals from the subtraction systems 312 (a) - (c) are provided to the demodulator of the traffic channel 310 (a) - (c), which isolates a traffic channel by carrying out a demodulation in sequence direct signal from the subtraction systems 312 (a) - (c) using the traffic channel code provided by the control system 305. In the preferred embodiment of the invention this demodulation constitutes the multiplication of the signals coming from of the delay circuits 311 with each chip of the traffic channel code, and adding the results of those multiplications to generate a voltage value that provides an estimate of the data that is transmitted. As mentioned above, a traffic channel carries the digital or digital audio data, or both associated with a particular communication, or telephone call. The result of the demodulation by a traffic channel demodulator 310 is a signal that provides an indication of the data that is transmitted through that traffic channel, which passes to the combiner system 314. The combiner system 314 combines the signals coming from of the set of traffic channel demodulators 310 to produce a more accurate estimate of the data that is transmitted. This more accessible estimate can then be processed by other signal processing systems within the subscriber unit 104 (fig 1). It should be noted that the estimates of the data provided by the FHT 308 systems will have a significant probability of error, in some cases approaching 10 percent (10%), which is ordinarily corrected finally through the detection coding process of mistake. This error rate, however, will generally be low enough that the substantial benefit is still provided by subtracting the level of the signal that is calculated based on those estimates. The above-described method of transferring audio and data information through the forward link portion of a wireless telecommunication system communication provides improved efficiency and performance, and an increased probability of exact transmission. This is because more of the unnecessary signaling is removed before an estimate of the data is made when compared to the previous system. The digitized signal received by a particular traffic channel demodulator 310 is comprised of the forward link signal 102 that is demodulated, other forward link signals 102, and background noise and other types of interference. In carrying out a fast Hadamard transformation on the other forward link signals 102, the signal levels associated with those forward link signals can be determined and removed using the subtraction circuits 312. The energy from the remaining signal it is comprised of the desired forward link signal 102 as well as the background noise and interference. In this way, a larger portion of the energy of the signals from the subtraction circuits 312 will be due to the desired forward link signal 102, and therefore the data associated with that desired forward link signal 102 can be be easier to determine using the traffic channel demodulators 310. The signal processing scheme described above is especially useful during the processing of the forward link portion of a wireless telecommunications system because the tracking of a single forward link signal 102 allows the energy associated with each of the multiple channels carried by that forward link signal 102 to be removed. This is significantly simpler than the tracking of multiple signals each associated with a type of information or communication carried by the channels, which is the case for the transmission of data through the reverse link from a subscriber unit 104 to a subscriber station. Additionally, the number of forward link signals 102 generated either through reflection or through the stations of the multiple base transceiver 100 (FIG. 1) is much smaller than the number of reverse link signals. generated by the set of subscriber units located within a given cell area, and therefore the portion of the energy that can be removed through such signal processing is much greater than in the reverse link, allowing a proportionality of the benefit greater to be achieved by a given amount of signal processing resources. In an alternative embodiment of the invention, the FHT 308 systems are replaced with channel demodulation systems similar to the traffic channel demodulators 310, except that the new channel demodulation systems will use a channel code associated with the pilot channel to demodulate the forward link signal 102. In some CDMA wireless telecommunications systems, the pilot channel contributes about twenty percent (20%) of the energy associated with a given forward link signal 102, which is done in order to facilitate the detection of the forward link signal that uses that pilot channel. By demodulation with the code of the pilot channel, the energy level associated with the pilot channel is determined, and this energy level can then be subtracted from the signals coming from the delay circuits 311 according to the subtraction of the energy levels detected by the FHT 308 systems as described above. Although subtracting the energy levels associated with the pilot channel alone does not provide much benefit as by subtracting the energy level associated with a full forward link signal 102, the resources of the signal processing necessary to demodulate with a single code are substantially smaller than those needed to carry out a fast Hadamard transformation. Since the pilot channel is responsible for a substantial portion of the total energy, much of the benefit of the system described above can be derived through the use of the pilot channel demodulation system with a substantial reduction in the signal processing resources required in relation to the use of the FHT 308 systems. In addition, in the preferred embodiment of the invention the channel code associated with the pilot signal is the Walsh code that contains all the zeros, and the data that is transmitted through the pilot channel is also of all the zeros, therefore when doing the demodulation and estimation of Data for the pilot channel is much simpler than necessary for any other channel. This second embodiment of the invention is even more suitable for use in the forward link portion of a wireless telecommunications system since a pilot signal is generally not used during the reverse link portion of many of the communications of the wireless telecommunications system of CDMA. In other alternative embodiments of the invention, other well-known systems for measuring the energy level associated with a forward link signal can be replaced by FHT systems 308. Additionally, other systems that estimate the energy associated with a channel different from the pilot channel, or that estimate the energy associated with a subset of all available channels. In this way, an improved method and apparatus for processing the forward link portion of a communication of the wireless telecommunications system is described. The description of the preferred embodiment is provided to allow any person skilled in the art to make or use the present invention. It will be readily apparent to one skilled in the art that various modifications of the invention, and the generic principles defined therein, can be applied to other embodiments without the use of the inventive faculty. In this manner, the present invention is not intended to be limited to the embodiments shown herein, but to be in accordance with the broadest scope consistent with the principles and novel features set forth herein.

Claims (16)

1. NOVELTY OF THE INVENTION Having described the present invention, it is considered as a novelty and therefore the property described in the following claims is claimed as property. A method for processing the forward link portion of a communication of the wireless telecommunications system comprising the steps of: (a) receiving a first forward link signal and second forward link signal; (b) estimating a data value that is transmitted through said first forward link signal; (c) generating an ideal waveform based on said data value; (d) subtracting said ideal waveform from said second forward link signal; and (e) determining a data value that is transmitted through said second forward link signal.
2. 2. The method according to claim 1 characterized in that said first forward link signal has a plurality of channels generated by adding a set of data types modulated with a set of corresponding channel codes, and step (b) is comprised of of the step of carrying out a fast Hadamard transformation on said first forward link signal.
3. 3. The method according to claim 1 characterized in that said first forward link signal has a plurality of channels generated by adding a set of data types modulated with a set of corresponding channel codes, and step (b) is comprised of of the step of demodulating said first forward link signal with a channel code associated with a pilot channel.
4. 4. The method according to claim 1, characterized in that said first forward link signal and said second forward link signal are generated by the same base transceiver station.
5. The method according to claim 1 characterized in that said first forward link signal is transmitted from a first base transceiver station, and said second forward link signal is transmitted from a second base transceiver station.
6. 6. The method according to claim 1, characterized in that step (b) is comprised of the steps of: (b.l) determining a set of data values that are transmitted through said first forward link signal; (b.2) calculate a set of ideal waveforms based on said set of data values; and (b.3) adding said set of ideal waveforms.
7. 7. A subscriber unit of the wireless telephone system comprising: means for receiving a first forward link signal and a second forward link signal; means for estimating a data that is transmitted through said first forward link signal; means for generating an ideal waveform in response to said data; means for removing said ideal waveform from said second forward link signal; and means for determining a data value that is transmitted through said second forward link signal.
8. The subscriber unit of the wireless telephone system according to claim 7, characterized in that said first forward link signal has a plurality of channels generated by summing a set of data types modulated with a set of corresponding channel codes, and said means to estimate are comprised of means for carrying out a rapid Hadamard transformation on said first forward link signal.
9. 9. The subscriber unit of the wireless telephone system according to claim 7, characterized in that said first forward link signal has a plurality of channels generated by summing a set of data types modulated with a set of corresponding channel codes, and said means to determine are comprised of a means for demodulating said first forward link signal with a channel code associated with a pilot channel.
10. 10. The subscriber unit of the wireless telephone system according to claim 7, characterized in that, said first and second forward links are generated by a first base transceiver station.
11. 11. The subscriber unit of the wireless telephone system according to claim 8, characterized in that said means for generating are comprised of: means for generating a set of ideal waveform based on a set of estimates from said means to perform a data value that is transmitted through said first forward link signal; and means for adding said set of ideal waveforms.
12. The subscriber unit of the wireless telephone system as set forth in claim 7, characterized in that said first forward link signal is received from a first base transceiver station, and said second forward link signal is received from of a second base transceiver station.
13. 13. A wireless telecommunications system for transmitting data comprising: a first base transceiver station for transmitting a first forward link signal; a second station of the base transceiver for transmitting a second forward link signal; and a subscriber unit for estimating the data that is transmitted through said first forward link signal, to generate an ideal waveform in response to said data to subtract said ideal waveform from said second forward link signal and to determine a data value that is transmitted through said second forward link signal after said ideal waveform has been subtracted.
14. The wireless telecommunications system according to claim 13 characterized in that said first forward link signal has a plurality of channels generated through direct sequence modulation using a set of channel codes, and said means for determining are comprised of of means for carrying out a fast Hadamard transformation
15. 15. The wireless telecommunication system according to claim 13 characterized in that said first forward link signal has a plurality of channels generated through direct sequence modulation using a set of channel codes, and said wireless subscriber unit is comprised of means for demodulating said first forward link signal with a channel code associated with a pilot channel.
16. 16. The wireless telecommunications system according to claim 13, characterized in that said first and second forward link signals are simultaneously received.