Communications of data in a communication system

[0001] The present invention relates generally to the field of communication, and more specifically, reverse link communication in a communication system.

BACKGROUND ART [0002] Reverse link transmissions may require transmitting a pilot signal from mobile stations to allow the receiver at the base station to perform coherent multi-path summation and demodulation. Typically, to find the optimal power level for the combined transmission power level of the pilot channel and data channels, the power level in the case of the pilot channel is minimized when attempting to achieve efficiency with a certain decoding error rate. For example, in the system generally known as cdma2000 1x, in the case of the 9600 bit / s format with a FER-frame error rate of 1%, the optimal pilot channel power level was experimentally determined to be about 3.75 dB lower, than the data channel power level. As the pilot channel power level increases well above such a specified level, the overall decoding efficiency does not improve significantly, although the overall transmit power for the pilot channel and data channels is higher. On the other hand, when the pilot channel power level drops significantly below such a specified level, the data channel power level needs to be increased to achieve the same decoding error rate. In this case, the total power level for the pilot channel and data channels is also higher. Thus, there exists some optimal pilot channel power level relative to the data channel power level, for a certain data transfer rate at a decoding efficiency level with a certain error rate. The graph shown in fig. 6 may illustrate the optimal pilot channel power level, relative to the total power level used for pilot channel and data channel transmission. The optimal power level may be different for different data rates. Higher data rates have a certain optimum pilot level, which can be significantly higher than the level of pilot required for low data rates. The difference in optimal pilot levels for low and high data rates can be around 13 dB.

[0003] The receiver of the power control process also measures the pilot channel power level to adjust the transmit power level. Typically, the receiver measures the signal to noise ratio (SNR) of the pilot channel. The measured SNR is compared to a certain threshold. If the measured SNR is higher than the threshold, then the receiver through the transmitter assigned to it gives to the source transmitting the command of reducing the pilot channel power. The data channel power level is also lowered to maintain a ratio of some pilot channel power level to the data channel power level. If the measured SNR is lower than the threshold, then the receiver through the transmitter assigned to it gives the source transmitting the command to increase the pilot channel power. The data channel power level is also increased to maintain a certain ratio of pilot channel power level to data channel power level. The receiving end as such, through the power control process, seeks to maintain the pilot SNR in the receiver for the correct implementation of the decoding process with a minimum error rate.

[0004] The communication system also includes a data rate control process that seeks to maximize the data rate for optimal data throughput. Based on the measured channel characteristic parameters, the data rate can be increased or decreased. In another aspect, the data rate may be changed on demand, assuming that the channel characteristic parameters ensure the correct communication on the requested data rate.

[0005] In such a communication system, pilot channel power control and data rate control may operate independently. Thus, when the data rate changes, the pilot channel power level can also change, without involving the power control process, while maintaining the optimal pilot channel power level. Because the power control process takes place without knowing the change in data transmission rate and the corresponding change in pilot channel power, the change in pilot channel power can be interpreted as a change in channel propagation in the power control process. Such detection normally initiates the pilot channel power change process through the power control process. Thus, if the change of the pilot channel power level, to ensure transmission with a different data rate, takes place without prior notification of the receiving end, the power adjustment process may incorrectly give the pilot channel a command to correct its transmit power.

[0006] Thus, there is a need for a power control process and a data rate control process that allows simultaneous operation in a communication system without adverse effects.

[0007] Document WO 03/017525 A1 describes a mobile station, MS, which transmits a primary and secondary pilot signal in various Walsh channels (i.e., in the main reverse pilot channel, R-PPICH - Reverse Primary Pilot Channel, and secondary reverse pilot channel, R-SPICH Reverse Secondary Pilot Channel). To control power, the P ratio_T/ Pp power varies in the range between (Pt / Pp) min and (Pt / Pp) max (where Pj is the combined pilot transmission power of R-PPICH and R-SPICH, and Pp the transmission power MS in R-PPICH and reverse traffic channel) ). Documents US-A-6 038 263, KR20010036597 A, WO 02/054618 A1 and Ylitalo: "Channel estimation study of CDMA downlink for fixed beam BTS" (Studies on channel estimation of CDMA downlink link for BTS constant beam), Nokia (published on 15.09.2002) contain a description of the transmission of the main and secondary pilot signals for the purpose of decoding / receiving data transmitted in the data (traffic) channel. BRIEF DESCRIPTION OF THE INVENTION [0008] The present invention relates to methods and a device as defined in the appended claims.

BRIEF DESCRIPTION OF THE FIGURES [0009] The characteristics, objectives and advantages of the present invention are more obviously derived from the following detailed description, including drawings, in which the same properties always identify the same references, respectively:

[0010] Fig. 1 shows a communication system for transmitting and receiving data in accordance with various aspects of the present invention;

[0011] Fig. 2 shows a receiver arrangement for receiving data in accordance with various aspects of the present invention;

[0012] Fig. 3 shows a transmitter system for transmitting data in accordance with various aspects of the present invention;

[0013] Fig. 4 is a flowchart of one or more stages at the transmitting end in accordance with various aspects of the present invention;

[0014] Fig. 5 shows a flowchart of one tube more stage at the receiving end in accordance with various aspects of the present invention.

[0015] Fig. 6 is a graph illustrating the optimal pilot channel power level relative to the total power level used for transmission on the pilot channel and data channels.

[0016] Fig. 7 shows the selection of the optimal total pilot channel power level.

DETAILED DESCRIPTION OF RELATED EMBODIMENTS [0017] The methods and apparatus provide effective data rate control and power control processes for transmitting the primary and secondary pilot channels associated with the data channel, as described in the claims. Pilot, primary and secondary channels are used to decode data. The basis for the ratio of pilot, primary and secondary channel power levels is at least one of the values, data transmission speed and size of the usable part of the data channel. The main pilot channel power level is maintained independent of at least one of the values, data transmission rate and size of the useful portion of the data channel. The power level of the secondary pilot channel can be set based on at least one of the values, data transmission speed and size of the useful portion of the data channel. One or more of the embodiments described herein are in the context of a digital wireless data transmission system. Although their use in this context is preferred, various embodiments of the invention may be incorporated in various environments or configurations. Generally, the various systems described herein may be created using software-controlled processors, integrated circuits, or discrete logic circuits. Data, instructions, orders, information, signals, symbols and semiconductor structures, references to which may appear throughout the application, are preferably represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles or a combination thereof. In addition, the blocks shown in each block diagram may represent equipment or method steps.

More specifically, various embodiments of the invention may form part of a wireless communication system operating in accordance with the multiple access code sharing method (CDMA) which has been shown and described in various standards published by the Telecommunications Industry Association (TIA - Telecommunication Industry Association) and other standardization organizations. Such standards include the TIA / EIA-95 standard, the TIA / EIA-IS-2000 standard, the IMT-2000 standard, UMTS and the WCDMA standard. The data transmission system is also described in detail in the documentation "TIA / EIA / IS-858 cdma2000 High Rata Packet Data Air Interface Specification" (Technical requirements TIA / EIA / IS-858 for the wireless interface cdma2000 high speed packet data transmission). A copy of the standards can be obtained by accessing the World Wide Web at: http://www.3qpp2.org, or by writing to the TIA, Standards and Technology Department, 2500 Wilson Boulevard, Arlington, VA 22201, in the United States of America. The standard, generally referred to as the UMTS standard, is achievable by contacting the 3GPP Support Office, 650 Route des Luuoles-Sophia Antipolis, Valbonne-France.

[0019] Fig. 1 is a general block diagram of a communication system 100 adapted to operate with any of the standards of code-sharing multiple-access communication systems (CDMA) comprising various embodiments of the invention. The communication system 100 can be used to transmit voice, data or both voice and data. Generally, communication system 100 includes a base station 101 that provides communication links between a number of mobile stations, e.g., 102-104, and between mobile stations 102-104 and public switched telephone network 105 and data transmission. Mobile stations in Fig. 1 can be referred to, without departing from the scope of the invention and its various advantages, as data access terminals (AT) and the base station as data access network (AN). The base station 101 may contain a number of components, such as, for example, a base station controller and a base transceiver system. For simplicity, such components are not shown. Base station 101 may be in communication with other base stations, e.g. base station 160. A switch of mobile communication (not shown) can control various aspects of the operation of the communication system 100 regarding direct links, back-haul 199, between network 105 and base stations 101 and 160.

[0020] Base station 101 communicates with each mobile station within its coverage area via a forward link signal transmitted from base station 101. Forward link signals for mobile stations 102-104 can be summed to form link signal 106 forward. A forward link may carry a number of different forward link channels. Each of the mobile stations 102-104 receiving forward link signal 106 decodes forward link signal 106, extracting information intended for its user. Base station 160 can also communicate with mobile stations in its coverage area via a forward link signal transmitted from base station 160. Mobile stations 102-104 can communicate with base stations 101 and 160 via appropriate links feedback. Each reverse link is maintained by a reverse link signal, e.g., reverse link signals 107-109, for mobile stations 102-104, respectively. Reverse link signals 107-109, although they may be targeted for one base station, may be received at other base stations.

[0021] Base stations 101 and 160 may be in simultaneous communication with a common mobile station. For example, mobile station 102 may be in close proximity to base stations 101 and 160, which may maintain communication with both base stations 101 and 160. In the forward link, base station 101 transmits signal 106 in the forward link and base station 160 signal 161 in the forward link. On the reverse link, mobile station 102 transmits a signal 107 on the reverse link received by both base stations 101 and 160. In the case of transmitting a data packet to mobile station 102, one of the base stations 101 and 160 may be selected to transmit a data packet to this mobile station 102. On a reverse link, both base stations 101 and 160 may proceed to decode the transmission of user data from the mobile station 102. The data rate and power level of the reverse link and the forward link may be maintained according to the channel state between the base station and the mobile station according to various aspects of the invention.

[0022] Fig. 2 is a block diagram of a receiver 200 for processing and demodulating a received CDMA signal when operating in accordance with various aspects of the invention. Receiver 200 can be used to decode information contained in uplink and forward link signals. Receiver 200 can be used to demodulate the pilot channel and decode information in data channels, e.g., the primary channel, the control channel and the auxiliary channels. The received (Rx) samples can be stored in RAM 204. The received samples are generated by a high frequency / intermediate frequency (RF / IF) system 290 with antenna system 292. The RF / IF system 290 and antenna system 292 may contain one or more components to receive multiple signals and to process RF / IF received signals to use the collective receive gain. Multiple received signals along various propagation paths may come from a common source. Antenna system 292 receives RF signals, and forwards RF signals to RF / IF 290. RF / IF 290 can be a conventional RF / IF receiver. The received RF signals are filtered, down-converted, and digitized to form RX samples at baseband frequencies. Samples are fed to the multiplexer (mux) 252. The output of the mux 252 multiplexer is fed to the search unit 206 and toes 208. Control system 210 is attached to them. Adder 212 couples decoder 214 to finger elements 208. Control system 210 may be a microprocessor controlled by software that may be located in the same or a separate integrated circuit. The decoding function at the decoder 214 may be implemented according to the turbo decoder algorithm or any other suitable decoding algorithms. The signal transmitted from the source can be coded through several layers of codes. As such, the decoder 214 decodes the received samples according to such codes.

[0023] During operation, the received samples are fed to the mux 252 multiplexer. The mux 252 multiplexer provides samples to the search unit 206 and finger elements 208. The control unit 210 configures the finger elements 208 to perform demodulation and despreading of the received signal with different time shifts. based on search results from search unit 206. Demodulation results are added together and forwarded to decoder 214. Decoder 214 decodes data and outputs the decoded data. Concentration (despreading) in channels is accomplished by multiplying the received samples by complex conjugated pairs of PN sequences and assigned Walsh function for a single timing hypothesis, and digital filtering of the resulting samples, often using an integral-accumulation system (not shown). Such a method is generally known in the art. Receiver 200 can be used in the receiving portion of base stations 101 and 160 to process received uplink signals from mobile stations, and in the receiving portion of any of the mobile stations to process received uplink signals forward.

[0024] The decoder 214 may accumulate the sum of energy for detecting a data symbol. Each data packet may contain a cyclic redundancy check (CRC) field. Decoder 214 may, in conjunction with control system 210 or other control systems, check for a received data packet for errors. If the given CRC does not match, the received data packet was received incorrectly. Control system 210 or other control systems may send a negative confirmation message to the transmitter for retransmitting the data packet.

[0025] Fig. 3 is a block diagram of a transmitter 300 for transmitting uplink and forward link signals. Transmission channel data is input to modulator 301 for modulation. The modulation can be compatible with any of the generally known modulation methods, such as QAM, PSK or BPSK. Before modulation, the channel data for transmission may pass through one or more coding layers. Transmission channel data is generated for modulator 301. The channel data for transmission is received by the 301 modulator.

[0026] The data modulation rate may be selected by the data rate and power level selector 303. The choice of data transfer rate can be based on the feedback information received from the destination. The data transmission rate is often selected based on the channel status, among other factors taken into account. The channel status may change from time to time. From time to time, the data rate selection may also change.

[0027] The data rate and power level selector 303 selects the data rate in the modulator 301. The output waveform of the modulator 301 passes through the signal spreading and gain operation in block 302 for transmission from the antenna 304. The data rate and power level selector 303 also selects the level power for the amplification level of the transmitted signal. The combination of selected data rate and power level allows correct decoding of transmitted data at the destination of reception. Also, at block 307, a pilot signal is generated. The pilot signal in block 307 is amplified to the appropriate level. The pilot signal power level may depend on the state of the channel at the destination. The pilot signal can be combined with the channel signal in adder 308. The combined signal can be amplified in the 309 amplifier and transmitted from the 304 antenna. The 304 antenna can be in any number of combinations, including antenna assemblies and configurations with multiple inputs and multiple outputs.

[0028] In Fig. 4, flowchart 400 illustrates one or more steps at the transmitting end in accordance with various aspects of the invention. The transmitting end, in the case of a reverse link in communication system 100, may be mobile stations, and the transmitter may be transmitter 300. According to various aspects of the invention, the problem of competition between data rate and power control processes is solved by transmitting the use of multiple (more than one ) pilot channels. Mobile stations transmit more than one pilot channel associated with a reverse link. In one embodiment, the mobile stations transmit two pilot channels associated with data channel transmission. At 401, the mobile station determines the data rate of the data channel for transmission to the receiving end, e.g., base station 101 or 160. The data rate may be determined based on processes known in the art. Such processes include determining the data rate based on the characteristics of the propagation channel or the desired data rate. Data rates can range from a certain lower value to a certain upper value. The standard detailing the operational requirements of the communication system 100 may define this scope. At step 402, the determined data rate is compared with a certain setpoint. The setpoint can be, for example, a data transmission rate between 38,400 bits / s and 115,200 bits / s. In step 403, if the determined data rate is higher than the setpoint, the mobile station transmits the primary pilot channel and the secondary pilot channel in accordance with various aspects of the invention. The main pilot channel power level is determined regardless of the determined data rate. The main pilot channel power level is usually determined in accordance with the power control process; however, according to one embodiment, the power level does not change with respect to the determined data rate. The secondary pilot channel in accordance with various aspects of the invention is transmitted at a power level higher than the main pilot channel. The power level of the secondary pilot channel can be 19 times higher than the power level of the main pilot channel.

[0029] In general, the system may provide data transmission at a number of different data rates. The number of data rates lower than the setpoint may be greater than one. The number of data rates greater than the setpoint can also be greater than one. In the embodiment, the speeds above the setpoint are: 115,200 bits / sec, 230,400 bits / sec and 307,200 bits / sec, while the speeds above the set point are 9,600 bits / sec, 19,200 bits / sec and 38,400 bits / sec.

[0030] The data rate values ​​may be replaced by the useful portion size values, or any other parameter that by its value indicates a correlation in at least one aspect with the data rate. Thus, the set value refers to such values ​​of such parameters. In an embodiment, the system may use hybrid automatic retransmission (HARQ). In this case, data rates may not be explicitly specified because the data rate depends on the number of frame transmissions that the data packet may require for full transmission from the sending end and correct reception at the receiving end. In this type of system, the setpoint can be the size of the useful portion of the frame or time period. The usable sizes can include 192, 384, 768, 1536, 3072, 4608 and 6144 bits. The usable part sizes of 192, 384, 768 and 1536 bits may be smaller than the set value. Therefore, any data transmission at such usable sizes takes place without a secondary pilot. The usable part sizes of 3072, 4608 and 6144 bits can be larger than the set value. Therefore, any data transmission with such useful part sizes is done with a secondary pilot.

[0031] In accordance with various aspects of the present invention, the power level of the main pilot channel does not change with the data rate. Accordingly, although the data rates are lower than the setpoint when the secondary pilot channel is not transmitted, the power level of the main pilot channel is independent of the data rate. According to various aspects of the invention, the power levels of the primary and secondary pilot channels at data rates greater than the setpoint remain independent of the data rate. The power levels of the primary and secondary pilot channels, in one embodiment, remain in the same ratio for all data rates above the set point.

[0032] Fig. 5 is a flowchart 500 for receiving and decoding data channel according to various aspects of the present invention. At step 501, the receiver can receive the main pilot channel. The receiver may be a base station in the communication system 100. The receiver may be the receiver 200 shown in Fig. 2. At step 502, the receiver determines whether the received primary pilot channel is transmitted along with the secondary pilot channel. Such detection can take place by searching for the energy level of the secondary pilot channel greater than a certain energy threshold, or less than the energy level of the main pilot channel. Since the secondary pilot channel is transmitted at a much higher level, the detection of such an energy level can easily be carried out by the receiver 200 very quickly, for example within one 1.25 ms interval. If a secondary pilot channel was detected in step 503, then the receiver 200 may combine the first and second pilot channels to improve the phase estimator and amplitude by multiplexing other channels, e.g., data channels in the receiver structure 200. It is obvious to the skilled person that the improved phase and amplitude reference also favors other types of loads, e.g. correctors. It is also obvious to the specialist that the ability to quickly detect the presence of the secondary pilot and its level relative to the main pilot is a big advantage for the implementation, because it directly reduces the amount of memory necessary in the receiver to buffer the signal before multipath summation. At the receiver 200, this additional memory requirement would increase the RAM sample memory size 204 or the memory added at the front of each finger element 208, and thus increase its complexity.

[0033] When the main pilot is transmitted without the secondary pilot channel, the SNR estimation in the case of power control may be based on the received main pilot channel signal. When the primary pilot is transmitted together with the secondary pilot channel, SNR estimation can be based on the received secondary pilot channel signal because the secondary pilot channel can be transmitted with a higher signal level than the main channel. The combination of primary and secondary pilot channels determined in step 503 can also be used to generate a more accurate propagation channel SNR estimator for power control. SNR values ​​of pilot channels, primary and secondary, can be combined according to the weighted summation process. For example, more weight is assigned to the SNR value of the secondary pilot channel than the main pilot channel because the secondary pilot channel can be transmitted with a higher signal level than the main channel.

[0034] Based on the improved SNR determined in step 503, the efficiency of the power control process is also improved. An inaccurate SNR estimator reduces the power control efficiency by the most important inaccuracy in adjusting the receiver power to the desired value. For the power control process, the improved SNR estimator is compared to the power control threshold. If the SNR is higher than the threshold, the receiving end forwards the transmission power down command to the transmitting end. If the SNR is lower than the threshold, the receiving end forwards to the transmitting end the command to increase the transmit power level. In accordance with various aspects of the present invention, the power control process at the transmit end sets the power level of the main pilot channel according to the power control command. The power level of the secondary pilot channel is determined, in accordance with various aspects of the invention, based on a predetermined ratio with respect to the power level of the main pilot channel. Thus, when the power level of the main pilot channel changes in response to the power control command, the power level of the secondary pilot channel also changes accordingly; however, the power level ratio remains the same.

[0035] Also, when the channel changes over time, the delayed SNR estimator may reduce the quality of the power control process. Typically, the delay in SNR estimation for power control is 1 time interval. Because the time needed to detect the presence of a secondary pilot can also be one time interval, the main and secondary pilots can be added together without significant delay in SNR estimation. Therefore, power control still works when the channel changes over time.

[0036] The transmit end may also have to send a rate of indicator (RICH) channel along with transmitting data on the data channel. At step 504, the receiving end receives this RICH channel. The RICH channel is used to assist in determining by the receiving end the data rate in the data channel. The determined data transmission rate is used in the data channel decoding process. As such, the information received from the RICH must be accurate for correct and accurate decoding of the data channel. Generally, in the case of RICH channel decoding, the receiver makes several hypotheses about the data received on the RICH channel. Finally, the receiver chooses one of the hypotheses with the highest confidence level. Because the receiver needs to test several hypotheses, detection of the secondary pilot channel can help the receiver decode the RICH channel. The receiver as such, at step 505, decodes the RICH channel based on at least one hypothesis that the indication of the transmitted data rate corresponds to a data rate higher than the set value used in the transmitter to trigger the secondary pilot channel transmission. In one aspect, the receiver may ignore any result of the RICH decoding process corresponding to a data rate lower than the given data rate. Similarly, if the secondary pilot is not detected, then the data transmission rate is most likely lower than the set value used in the transmitter to trigger transmission of the secondary pilot channel. At step 506, the receiver decodes the data channel based on the decoded RICH. The decoding process can

- 9 include multi-path summation and demodulation processes. For the decoding process in step 506, an estimator with improved phase and amplitude reference may be used, determined in step 503.

[0037] In other aspects, RICH may be needed to carry less information if, in accordance with various aspects of the invention, secondary pilot channel transmission is used. When the need to transmit less information, the efficiency of the decoding process can be increased. For example, instead of the RICH channel providing 32 possible inputs for four subpackage identifiers and eight possible packet sizes, or providing 33 possible inputs with an additional zero rate indicator input, secondary pilot channel broadcast and detection can be used to reduce the amount of data indicating the number of encoder packet sizes possible for possible transmission. RICH processing of the data indicator can reduce the number of possible inputs to 16 (or 17 with a zero rate indicator), using secondary pilot channel detection to determine which of the four largest of the eight encoder packet sizes is used, and no secondary pilot channel detection to determine which of the smallest four encoder packages is used. In an embodiment, the encoder packet sizes can be 192 bits and 384 bits. Subpackage identifiers can have '0' and '1' values. Therefore, the RICH may contain any of the 4 code words corresponding to the size of the encoder packet, and a certain subpackage identifier. RICH code words can be "00", "01", "10" and "11". If the presence of a secondary pilot is used to infer the useful portion size, then RICH can only use 2 code words, for example, "00" and "01". [0038] In another embodiment, the power level of the secondary pilot channel may be selected higher than the main pilot channel in accordance with a number of predetermined ratios. For example, if the data channel transmission rate is higher than the first setpoint but lower than the second setpoint, the power level of the secondary pilot channel is higher than the main pilot channel in the specified first ratio. Also, if the data rate of the data channel is higher than the second set value, then the power level of the secondary pilot channel is higher than the main pilot channel according to the second predetermined ratio. At the receiving end, after detection of the main pilot channel, the power level of the secondary pilot channel may determine the range of expected values ​​from RICH decoding. If the ratio of the received power level of the pilot, main and secondary channels corresponds to the first ratio, then the expected value from RICH decoding may be between the pre-determined values, first and second. If the ratio of the received power level of the pilot, primary and secondary channels corresponds to the second ratio, then the expected value from RICH decoding may be higher than the second pre-determined value.

[0039] The selection of the optimal total power level of the pilot channels can be described by the graphs shown in Fig. 7. For the R4, R5 and R6 data transmission rates, the power level of the combined pilot, primary and secondary channels is selected such that the total power level corresponds the optimal power level closest to the level appropriate for the data rates of R4, R5 and R6 data transmission. For R1, R2 and R3 data transmission rates, the pilot power level consists of the main pilot channel power level. Similarly, the combined pilot power is selected such that the power level is close to the level appropriate for the data rates R1, R2 and R3. The setpoint that determines if the secondary pilot channel should be transmitted is between R3 and R4. As such, the pilot channel power level is selected as close as possible to the optimal level, however, enabling data rate control and power control processes to operate without conflict between the needs of broadcasting with a higher pilot power level for high data rates, and the power control based on received SNR pilot channel.

[0040] It is also obvious to the skilled person that the various illustrative logic blocks, modules, circuits and steps of the algorithm described in connection with the embodiments described herein can be implemented as electronic circuits, computer software, or as a combination of both. To clearly illustrate this interchangeability of circuits and software, various exemplary components, blocks, modules, circuits and steps are described above generally in terms of their functionality. Whether such functionality is implemented systemically or programmatically depends on the specific application and design restrictions imposed on the entire system. Skilled artisans may implement the described functionalities in a variety of ways for each particular application, but such implementation decisions should not be interpreted as going beyond the scope of the present invention.

[0041] Various exemplary logic blocks, modules and circuits described in connection with the embodiments described herein may be implemented or implemented using a universal processor, digital signal processor (DSP), specialized integrated circuit (ASIC), directly programmable gate matrix (FPGA) or other programmable logic element, discrete gate or logic on transistors, discrete system components, or any combination thereof intended to perform the functions described in this document. The universal processor may be a microprocessor, although alternatively this processor may be a conventional processor, controller, microcontroller or state machine. The processor can also be implemented as a combination of counting assemblies, e.g., a combination of a DSP processor and a microprocessor, a set of microprocessors, one or more microprocessors coupled to a DSP core, or any other such configuration.

[0042] The steps of the method, i.e. the algorithm described in connection with the embodiments shown herein, can be implemented directly in the systems, in the program module executed by the processor or in a combination thereof. The program module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium is attached to the processor such that the processor can read from the storage medium and write information to it. Alternatively, the storage medium may be integral with the processor. The processor and storage media may reside in the ASIC. The ASIC may be in the user terminal. Alternatively, the processor and storage medium may be in the form of discrete parts in the user terminal.

[0043] The above description of preferred embodiments is provided to enable the skilled person to implement or use the present invention. Various modifications to these embodiments are obvious to those skilled in the art, and the general principles set out herein may apply to other implementations without having to demonstrate innovative progress. Thus, it should be considered that the present invention is not limited to the embodiments shown, but is consistent with the widest scope in accordance with the principles disclosed therein and the new characteristics set forth in the claims.