Source: https://patents.google.com/patent/US6934319B2/en
Timestamp: 2018-11-16 07:47:38
Document Index: 420017012

Matched Legal Cases: ['art 5000', 'art 5000', 'art 5000', 'art 5000', 'art 5000', 'art 5000', 'art 5000', 'art 5000', 'art 5100', 'art 5000', 'arts 5000', 'arts 5000', 'art 5000', 'art 5000']

US6934319B2 - Configurable multimode despreader for spread spectrum applications - Google Patents
Configurable multimode despreader for spread spectrum applications Download PDF
US6934319B2
US6934319B2 US09751785 US75178500A US6934319B2 US 6934319 B2 US6934319 B2 US 6934319B2 US 09751785 US09751785 US 09751785 US 75178500 A US75178500 A US 75178500A US 6934319 B2 US6934319 B2 US 6934319B2
Expired - Fee Related, expires 2023-02-09
US09751785
US20010040915A1 (en )
A configurable multimode despreader for spread spectrum applications is disclosed herein. The despreader includes a plurality of data lines, at least one selective coupler coupled to the plurality of data lines, at least one multiplier coupled to the selective coupler, and a code input line coupled to the multiplier. The selective coupler selectively couples one of the plurality of data lines with the multiplier per any one of a plurality of despreading protocols. The multiplier then multiplies a desired input data type received from the selective coupler with a despreading code chip received from the code input line to produce an observation. The programmable multimode despreader supports variable code and data modulation schemes and variable spreading factors.
This application claims priority to the provisional patent application with the following Ser. No. 60/173,634, filed on Dec. 30, 1999.
A CONFIGURABLE ALL-DIGITAL COHERENT DEMODULATOR SYSTEM FOR SPREAD SPECTRUM APPLICATIONS Ser. No. 09/751,783
APPARATUS AND METHOD FOR CALCULATING AND IMPLEMENTING A FIBONACCI MASK FOR A CODE GENERATOR Ser. No. 09/751,776
A FAST INITIAL ACQUISITION & SEAR DEVICE FOR A SPREAD SPECTRUM COMMUNICATION SYSTEM Ser. No. 09/751,777
A CONFIGURABLE CODE GENERATOR SYSTEM FOR SPREAD SPECTRUM APPLICATIONS Ser. No. 09/751,782
METHOD AND APPARATUS TO SUPPORT MULTI STANDARD, MULTI SERVICE BASE-STATIONS FOR WIRELESS VOICE AND DATA NETWORKS Ser. No. 09/752,050
IMPROVED APPARATUS AND METHOD FOR MULTI-THREADED SIGNAL PROCESSING Ser. No. 09/492,634, filed on Jan. 27, 2000
The present claimed invention relates to the field of wireless communication. In particular, the present claimed invention relates to an apparatus and a method for despreading digital spread-spectrum signals in a wireless communication system.
Wireless communication has extensive applications in consumer and business markets. Among the many communication applications/systems are: fixed wireless, unlicensed (FCC) wireless, local area network (LAN), cordless telephony, personal base station, telemetry, mobile wireless, and other digital data processing applications. While each of these applications utilizes spread spectrum communications, they generally utilize unique and incompatible spreading protocols for signal transmissions. This corresponds to unique despreading protocols and algorithms for receiving the signals. Consequently, each application may require unique hardware, software, and methodologies for despreading. This practice can be costly in terms of design, testing, manufacturing, and infrastructure resources. As a result, a need arises to overcome the limitations associated with the varied hardware, software, and methodology of despreading digital signals for each of the varied wireless applications.
Complete demodulation of the radio waveform requires that the signal be processed by a specific step referred to as ‘despreading.’ The channel codes utilized for despreading relate to the complexity of the radio receiver design and channel width of the transmission. As new generations of protocols and hardware arise in any of the varied applications, they are sometimes sufficiently different from the previous generation as to render legacy systems incompatible or unusable. This situation arises from the equipment that has been developed using a standard-centric perspective. Consequently, new software, hardware, or infrastructure may be required to accommodate a new protocol in a given despreader application. Again, this practice can be costly in terms of design, testing, manufacturing, and infrastructure resources. Consequently, a need arises to overcome the lack of backward and forward compatibility associated with new generations of despreading protocols, hardware, and infrastructure within any of the varied wireless applications.
The present invention provides a solution to the limitations of varied hardware, software, and methodology of despreading/descrambling digital signals in each of the varied wireless applications. The present invention also provides a solution to conventional limitations of backward and forward compatibility associated with new generations of spreading and channelization protocols, hardware, and infrastructure within any of the varied wireless applications. Furthermore, the present invention provides alternatives to the limitations of noise and interference with despreading. The present invention also overcomes the limitations associated with the variations and incompatibility of different spreading factors used to spread a signal at a transmitter device. Lastly, the present invention accomplishes these items while addressing variations in the noise level of a signal under different operating environments.
Referring now to FIG. 1, a block diagram of an electronic communication device having a multimode despreader is shown, in accordance with one embodiment of the present invention. Electronic communication device 100 is a wireless code division multiple access (CDMA) base station in the present embodiment, e.g., cellular telephony. However, the present invention is well suited to use in a mobile handset, a test platform, an embedded wireless modem, or other communication device. Furthermore, the present invention is applicable to any electronic device needing to despread a data signal. Communication device 100 is operable as described in a subsequent flowchart.
Base band processor 106, which is operable to process the recovered digital signal delivered by a source following front-end processing operations, includes components such as a multimode despreader 110, a multipath estimator 108, a code generator unit (CGU) 109, and a function block 116. Multipath estimator 108 and CGU 109 are coupled to multimode despreader 110 in parallel. Function block 116 is coupled to receive the output of multimode despreader 110. It is appreciated that estimator 108 perform functions such as channel estimation, and that function block 116 performs signal processing operations, such as decoding, that are known to those skilled in the art. Multimode despreader 110 is capable of despreading a complex signal and providing a complex despread signal, represented by wide interconnect 120 b. Multipath estimator communicates estimation results with multimode despreader via line 120 c.
In one embodiment, multiple physical instances of multimode despreader 110 can be utilized in communication device 100 to accommodate multiple input channels in order to realize a rake receiver, or to process multiple fingers. Alternatively, multimode despreader 110 is capable of providing multiple virtual despreading functional planes to accommodate this same goal. Multimode despreader 110 can also be used for multiple despreading fingers. This can be realized via a multi-threaded, time-shared architecture that utilizes dynamic resource allocation and scheduling.
CGU 109 provides the despreading codes necessary for processing the spread signal. In one embodiment, CGU 109 is configurable to provide one of the many despreading codes, e.g., long or short codes, that are capable of being implanted in programmable multimode despreader 110. Additional detail on the configurable code generator is provided in the above-referenced co-pending U.S. patent application Ser. No. 09/751,782, filed Dec. 29, 2000 entitled “A CONFIGURABLE CODE GENERATOR SYSTEM FOR SPREAD SPECTRUM APPLICATIONS” (attorney docket number 9824-0029-999).
CGS 114 a is a hardware computation resource that can be applied to a single computation process, e.g., a multipath of a given channel, in one embodiment. However, in another embodiment, the computation resource provided by CGS 114 a can be enhanced by running CGS 114 a at a clock rate higher than that required by a process, e.g., higher than the data rate for a communication protocol. In this manner, resources of individual computation components, such as CGS 114 a, can be time-shared across multiple computation processes, e.g., several multipaths and/or multiple channels. Additional information on the design and implementation of configurations into a configurable communication device is provided in co-pending U.S. patent application Ser. No. 09/492,634 entitled “IMPROVED APPARATUS AND METHOD FOR MULTI-THREADED SIGNAL PROCESSING” by Subramanian et al., attorney docket number MORP-P002. This related application is commonly assigned, and is hereby incorporated by reference.
Multimode Despreader
Referring now to FIG. 2A, a block diagram of the major components in a multimode despreader are shown, in accordance with one embodiment of the present invention. Multimode despreader 110 includes a local controller 226, a multimode despreader kernel 222, and a memory block 224 in the present embodiment. Multimode despreader kernel 222 is a satellite kernel, which is algorithmic-specific in the present embodiment. That is, while despreader kernel 222 is a configurable electronic device capable of performing a wide range of algorithms, the algorithms are nonetheless limited to the class of despreading functions. An exemplary description of a multimode despreader kernel 222 is described in subsequent FIG. 2B.
Referring now to FIG. 5A, a flowchart of the process used to operate a despreader having multiple modes of operation is shown, in accordance with one embodiment of the present invention. Flowchart 5000 is implemented, in the present embodiment, using exemplary block diagrams of FIGS. 1, 2A-2B, and 3. However, flowchart 5000 is only applied to half the multimode despreader for purposes of clarity, the other half of multimode despreader being complementary. Flowchart 5000 can effectively be used to despread input data having a wide range of modulation schemes in conjunction with a wide range of spreading modulation schemes. By using the present flowchart embodiment, the present invention provides a method of accommodating a wide range of spread spectrum communication applications and protocols.
In step 5008 of the present embodiment, an inquiry determines whether the desired transmission uses an ‘A’ method, ‘B’ method, or ‘M’ method of code modulation for spreading a signal. These methods can be any desired type of code modulation. For example, ‘A’ method of code modulation modulates only the real portion of a signal, while the ‘B’ method modulates a real and complex portion of the signal, and ‘M’ method utilizes M-ary code modulation, in the present embodiment. M-ary code modulation refers to communicating using M symbols such as a binary case with M=2, a quaternary case with M=4, etc.
Step 5010 arises if the transmission method uses the ‘A’ method of code modulation for spreading a signal. In step 5010 of the present embodiment, the real portion of the data signal is provided for subsequent despreading operations. Step 5010 is implemented by communicating I-sample input 236 a, and by not communicating Q-sample input 236 b, through MUX A 278, as shown in FIG. 2B. Following step 5010, flowchart 5000 proceeds to step 5014.
Step 5012 arises if the transmission method uses the ‘B’ method of code modulation for spreading a signal. In step 5012 of the present embodiment, a quadrature portion of the data signal is provided for subsequent despreading operations. Step 5012 is implemented by communicating Q-sample input 236 b, and by not communicating I-sample input 236 a, through MUX A 278, as shown in FIG. 2B. Following step 5012, flowchart 5000 proceeds to step 5014.
Step 5013 arises if the transmission method uses the ‘M’ method of code modulation for spreading a signal. In step 5013 of the present embodiment, a M-phase portion of the data signal being provided for subsequent despreading operations. Step 5013 is implemented by communicating an M-sample input 236 b, and by not communicating I-sample input 236 a, through MUX A 278, as shown in FIG. 2B. Following step 5013, flowchart 5000 proceeds to step 5014.
In step 5014 of the present embodiment, the despreading code is multiplied by the selected input data type identified in steps 5008-5012. Step 5014 is implemented in the present embodiment, by multiplier 272 of FIG. 2B selectively multiplying either the I-sample or the Q-sample times the despreading code. The multiplication operation produces a product output 5014 a that is referred to as an ‘observation.’ Step 5014 is represented mathematically as: I-sample * Q-code for step 5010, while 5014 is represented mathematically as: Q-sample * Q-code for step 5012. Again, the specific choice of products in 5014 is determined by the transmission method for spreading, which is determined a priori. Multiplication operation steps can be implemented as correlation operations or pipeline correlation operations. Following step 5014, flowchart 5000 proceeds to step 5018.
Step 5016 of the present embodiment receives an additional despread code is. In particular, code ‘B’ input 5016 a is received for despreading. Step 5016 provides for a complex methodology of despreading. That is, step 5016 is implemented in the present embodiment by receiving a real, or in-phase, despreading code sequence I-code 237 a, as shown in FIG. 2B. Following step 5016, flowchart 5000 proceeds to step 5018.
Accumulate A Accumulate A
Accumulate A′ Accumulate A′
Observation Observation Observation Observation
In the present embodiment, Flowchart 5100 is parallely implemented for a set of code and input signal products complementary to the set of code and input signal products implemented by steps 5102-5118 hereinabove. Thus, in the parallel implementation, accumulate and dump circuits 263 and 264 receive, accumulate, and dump the observation products from multiplier 273 and 274, per observation length A 114 a, as shown in FIG. 2B. In a complementary manner, these products are communicated from interface circuit 259, per enable B 114 b, to produce a Q-symbol output 256 b.
While flowchart 5000 of the present embodiment shows a specific sequence and quantity of steps, the present invention is suitable to alternative embodiments. For example, not all the steps provided in flowcharts 5000 are required in alternative embodiments of the present invention. For example, step 5016 is not required for a despreader protocol that only utilizes real despreading codes. However, in an alternative embodiment, the parallel comparison step is not needed because it is replaced by a single comparison operation. Furthermore, the present invention is well suited to incorporating additional steps to those presented, as required by an application, or as desired for permutations in the process. Finally, the sequence of the steps for flowcharts 5000 and 5100 can be modified depending upon the application. Thus, while flowchart 5000 and 5100 are shown as a single serial process, it can also be implemented as a continuous or parallel process. For example, is appreciated that flowchart 5000 can be repeated for each of multiple instances of a multimode despreader within a communication device, e.g., device 100.
It should be borne in mind, however, that all of these terms are to be interpreted as referencing physical manipulations and quantities and are merely convenient labels to be interpreted further in view of terms commonly used in the art. Unless specifically stated otherwise as apparent from the following discussions, it is understood that throughout discussions of the present invention, terms such as “receiving,” “communicating,” “multiplying,” “accumulating,” “repeating,” “dumping,” “adding,” “accepting,” or the like, refer to the action and processes of a communication device or a similar electronic computation device, that manipulates and transforms data. The data is represented as physical (electronic) quantities within the communication devices components, and is transformed into other data similarly represented as physical quantities within the communication device components, or computer system memories or registers, or other such information storage, transmission or display devices.
a plurality of data lines for receiving a plurality of input data types; at least one selective coupler coupled to the plurality of data lines;
a first multiplier coupled to the selective coupler, the first multiplier for multiplying a desired input data type received from the selective coupler with a despreading code chip to produce a first observation; and
a first code input line coupled to the multiplier, the first code input line for receiving the despreading code chip;
wherein the selective coupler selectively couples one of the plurality of data lines with the multiplier per any one of a plurality of despreading protocols.
2. The despreader recited in claim 1 wherein the plurality of data lines comprises:
an in-phase sample (I-sample) line for receiving an in-phase data sample;
a quadrature-phase sample (Q-sample) line for receiving a quadrature-phase data sample; and
a quadrature-phase code (Q-code) line for receiving a quadrature-phase code chip; wherein the selective coupler is coupled to the I-sample line, the Q-sample line and the multiplier, wherein the Q-code line is also coupled to the first multiplier, and wherein the selective coupler selectively couples either the I-sample line or the Q-sample line to the first multiplier.
3. The despreader recited in claim 2 further comprising:
a first accumulate and dump circuit coupled to the first multiplier, the first accumulate and dump circuit receiving the first observation from the first multiplier and having an enable input that selectively dumps a first accumulated sample after an observation period has been satisfied.
4. The despreader recited in claim 3 further comprising:
a second multiplier coupled to an additional code input line and to one of the plurality of data lines per a common portion of the plurality of despreading protocols.
5. The despreader recited in claim 4 further comprising:
an in-phase code (1-code) input line for receiving an in-phase code chip;
wherein the second multiplier is coupled to the I-code input line and to the I-sample input line, the second multiplier for multiplying an I-code input and an I-sample input to produce a second observation.
6. The despreader recited in claim 5 further comprising:
a second accumulate and dump circuit coupled to the second multiplier, the second accumulate and dump circuit receiving the second observation output by the second multiplier and having an enable input that selectively dumps a second accumulated sample after the observation period has been satisfied.
7. The despreader recited in claim 6 further comprising:
an interface circuit coupled to the first accumulate and dump circuit and the second accumulate and dump circuit, the interface circuit having an enable input allowing the interface circuit to communicate a detection statistic.
8. The despreader recited in claim 7 further comprising:
a memory coupled to the first accumulate and dump circuit and the second accumulate and dump circuit, the memory storing a value that dictates the observation period for the first accumulate and dump circuit and the second accumulate and dump circuit.
9. The despreader recited in claim 7 further comprising:
an additional selective coupler coupled to the I-sample line and the Q-sample line; and
a third multiplier coupled to the additional selective coupler and the I-code line;
wherein the additional selective coupler is coupled to the I-sample line, the Q-sample line and the third multiplier, wherein the I-code line is also coupled to the multiplier, and wherein the selective coupler selectively couples either the I-sample line or the Q-sample line to the third multiplier per any one of multiple despreading protocols.
10. The despreader recited in claim 9 further comprising:
a third accumulate and dump circuit coupled to the third multiplier, the third accumulate and dump circuit receiving a third observation output by the third multiplier and having an enable input that selectively dumps an accumulated sample after the observation period has been satisfied.
11. The despreader recited in claim 10 further comprising:
a fourth multiplier coupled to the Q-code input line and to the Q-sample input line, the fourth multiplier for multiplying the Q-code input and the Q-sample input to produce a fourth observation.
12. The despreader recited in claim 11 further comprising:
a fourth accumulate and dump circuit coupled to the fourth multiplier, the fourth accumulate and dump circuit receiving the fourth observation output by the fourth multiplier and having an enable input that selectively dumps an accumulated sample after the observation period has been satisfied.
13. The despreader recited in claim 12 further comprising:
an additional interface circuit coupled to the third accumulate and dump circuit and to the fourth accumulate and dump circuit, the additional interface circuit having an enable input allowing the additional interface to communicate a detection statistic.
14. The despreader recited in claim 1 further comprising:
a memory coupled to the selective coupler, the memory storing a value that enables the selective coupler to communicate a desired input data sample.
15. The despreader recited in claim 1 wherein the desired observation length is proportional to one of a plurality of spreading factors.
at least one multiplier for multiplying an input data sample with a despreading code chip; and
at least one accumulate and dump circuit coupled to the multiplier;
wherein the accumulate and dump circuit has an enable input that selectively dumps an accumulated sample after a variable observation period has been satisfied.
19. The despreader recited in claim 18 wherein the accumulate and dump circuit includes a comparator coupled to the enable input, the comparator for comparing a desired observation period with the actual observation period.
a memory coupled to the comparator, the memory for storing a value of the desired observation period.
21. The despreader recited in claim 19 further comprising:
a counter coupled to the comparator, the counter for counting the actual observation period.
22. The despreader recited in claim 18 further comprising:
an additional accumulate and dump circuit; and
an additional multiplier coupled to the additional accumulate and dump circuit, the additional accumulate and dump circuit receiving an output from the additional multiplier and having an enable input that selectively dumps an additional accumulated sample after the observation period has been satisfied.
23. The despreader recited in claim 22 further comprising:
an interface circuit coupled to the accumulate and dump circuit and to the additional accumulate and dump circuit, the interface circuit having an enable input allowing the interface circuit to communicate a detection statistic.
24. The despreader recited in claim 23 further comprising:
a memory coupled to the accumulate and dump circuit and the additional accumulate and dump circuit, the memory storing a value that dictates the observation length.
25. The despreader recited in claim 23 wherein the observation length is determined by a noise level of a signal being despread.
a radio frequency/intermediate frequency (RF/IF) transceiver;
an analog to digital (A/D) converter coupled to the RF/IF transceiver; and
a despreader having at least one multiplier coupled to a code input line and selectively coupled to a plurality of data input lines in a manner to satisfy any one of multiple despreading protocols.
27. The electronic communication device recited in claim 26 wherein the despreader includes at least one selective coupler coupled to the multiplier and the plurality of data input lines, the selective coupler for selectively choosing one of the plurality of data input lines to be coupled to the multiplier for a despreading operation.
a memory coupled to the selective coupler, the memory providing a signal that enables one of the plurality of data input lines to be coupled to the multiplier for the despreading operation.
29. The electronic communication device recited in claim 26 wherein the data processed is for a spread spectrum digital wireless protocol.
an additional multiplier coupled to the additional accumulate and dump circuit, the additional accumulate and dump circuit receiving an additional observation output from the additional multiplier and having an enable input that selectively dumps an accumulated result after the observation period has been satisfied.
32. The electronic communication device recited in claim 31 further comprising:
an interface circuit coupled to the accumulate and dump circuit and to the additional accumulate and dump circuit, the interface circuit having an enable input that allowing the interface circuit to communicate a detection statistic.
33. The electronic communication device recited in claim 32 further comprising:
a memory coupled to the accumulate and dump circuit and the additional accumulate and dump circuit, the memory storing a value that dictates the observation period for the accumulate and dump circuit and the additional accumulate and dump circuit.
34. The electronic communication device recited in claim 33 wherein the observation length is determined according to a noise level of a signal being despread.
an analog to digital (A/D) converter coupled to the RF transceiver; and
a despreader having at least one accumulate and dump circuit, the accumulate and dump circuit having an input that selectively dumps an accumulated sample after a variable observation period has been satisfied.
36. The electronic communication device recited in claim 35 wherein the despreader includes a comparator coupled to the accumulate and dump circuit, the comparator for comparing a desired observation length with an actual observation length.
an additional multiplier coupled to the additional accumulate and dump circuit, the additional accumulate and dump circuit receiving an additional observation from the additional multiplier and having an enable input that selectively dumps an additional accumulated sample after the observation period has been satisfied.
39. The electronic device recited in claim 38 further comprising:
40. The electronic device recited in claim 39 further comprising:
41. The electronic device recited in claim 40 wherein the observation length is determined according to a noise level of a signal being despread.
a) receiving a plurality of input data types at a selective coupler;
b) receiving a despreading code at a multiplier;
c) selectively communicating a desired input data type to the multiplier via the selective coupler, the desired input data type selected from the plurality of input data types per a desired despreading protocol; and
d) multiplying the desired input data type with the despreading code, via the multiplier, to produce an observation.
43. The method recited in claim 42 further comprising the steps of:
e) receiving an in-phase data sample (I-sample) at the selective coupler;
f) receiving a quadrature-phase data sample (Q-sample) at the selective coupler;
g) receiving a quadrature-phase code chip (Q-code) at the multiplier; and
h) selectively communicating either the I-sample or the Q-sample to the multiplier via the selective coupler per the desired despreading protocol.
44. The method recited in claim 43 further comprising the step of:
i) accumulating, at an accumulate and dump circuit, the observation produced by the multiplier;
j) receiving a first control signal at the accumulate and dump circuit indicating a desired observation length;
k) repeating steps a) through j) to generate an additional observation; and
l) dumping an accumulated sample from the accumulate and dump circuit after the desired observation length has been satisfied.
45. The method recited in claim 44 further comprising the steps of:
m) receiving an additional code chip at an additional multiplier;
n) receiving a first input data type amongst the plurality of input data types at the additional multiplier, the first input data type common between the plurality of despreading protocols; and
o) multiplying the additional code chip times the first input data type, via the additional multiplier, to produce an additional observation.
46. The method recited in claim 44 further comprising the steps of;
m) receiving an in-phase code chip (1-code) at an additional multiplier;
n) receiving the in-phase data sample (I-sample) at the additional multiplier; and
o) multiplying the I-code with the I-sample, via the additional multiplier, to produce an additional observation.
47. The method recited in claim 46 further comprising the steps of:
p) repeating in parallel, steps i) through k) for the additional observation at an additional accumulate and dump circuit to dump an additional accumulated sample.
48. The method recited in claim 47 further comprising the steps of:
q) receiving the accumulated sample from the accumulate and dump circuit at an interface circuit;
r) receiving the additional accumulated sample from the additional accumulate and dump circuit at the interface circuit;
s) receiving a second control signal at the interface circuit that enables the accumulated sample and the additional accumulated sample to be transmitted as a symbol; and
t) repeating steps q) through s) for a new symbol.
49. The method recited in claim 48 further comprising the steps of:
u) repeating in parallel steps a) through w) on a parallel set of components wherein step g) receives the in-phase code chip (I-code) at the multiplier, wherein step m) receives the quadrature-phase code chip (Q-code) at the additional multiplier, and wherein step n) receives the quadrature-phase data sample (Q-sample) at the additional multiplier.
50. The method recited in claim 42 wherein the desired observation length is proportional to one of a plurality of spreading factors.
a) receiving a first observation from a first multiplier at a despreader;
b) accumulating the first observation at a first accumulate and dump circuit;
c) receiving a first control signal at the first accumulate and dump circuit that indicates a desired variable observation length;
d) repeating steps a) through c) for a new observation; and
e) dumping a first accumulated sample from the first accumulate and dump circuit after the desired variable observation length has been satisfied.
54. The method recited in claim 53 further comprising the steps of:
f) repeating in parallel, steps a) through e) for a second observation received from a second multiplier at a second accumulate and dump circuit, the second accumulate and dump circuit providing a second accumulated result.
55. The method recited in claim 54 further comprising the steps of:
g) receiving the first accumulated result from the first accumulate and dump circuit at an interface circuit;
h) receiving the second accumulated result from the second accumulate and dump circuit at the interface circuit;
i) adding the first accumulated result and the second accumulated result in the interface circuit to obtain a sum;
j) receiving a second control signal at the interface circuit that enables the accumulated sample and the additional accumulated sample to be transmitted as a symbol; and
k) repeating steps g) through j) for a new symbol.
56. The method recited in claim 55 further comprising the steps of:
US09751785 1999-12-30 2000-12-29 Configurable multimode despreader for spread spectrum applications Expired - Fee Related US6934319B2 (en)
US17363499 true 1999-12-30 1999-12-30
US09751785 US6934319B2 (en) 1999-12-30 2000-12-29 Configurable multimode despreader for spread spectrum applications
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US11179356 Expired - Fee Related US8804789B2 (en) 1999-12-30 2005-07-11 Configurable multimode despreader for spread spectrum applications
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