HK1189102B - Pilot transmission in a wireless communication system - Google Patents

Description

Pilot transmission in a wireless communication system

The application is a divisional application of an invention patent application with the international application number of PCT/US2008/050328, the international application date of 2008/5.1.2008, the application number of 200880001748.6 entering the China national phase and the name of 'pilot frequency transmission in a wireless communication system'.

The provisional U.S. application S/n.60/883,758 entitled "WIRELESS COMMUNICATION SYSTEM" filed on 5/1/2007, provisional U.S. application S/n.60/883,870 entitled "PILOT signal transmission FOR a WIRELESS COMMUNICATION SYSTEM" filed on 8/1/2007, and provisional U.S. application S/n.60/883,982 entitled "PILOT signal transmission FOR a WIRELESS COMMUNICATION SYSTEM" filed on 8/1/2007, all of which are assigned to the present assignee and are hereby incorporated by reference.

Background

I. Field of the invention

The present disclosure relates generally to communication, and more specifically to techniques for transmitting pilots in a wireless communication system.

II. background

Wireless communication systems are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, and so on. These wireless systems may be multiple-access systems capable of supporting multiple users by sharing the available system resources. Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, orthogonal FDMA (ofdma) systems, and single carrier FDMA (SC-FDMA) systems.

A wireless communication system may include many base stations that may support communication for many terminals on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. Terminals can be located anywhere within the system, and each terminal can be within the coverage of zero, one, or multiple base stations at any given moment. The terminal may transmit pilot on the reverse link to allow the base stations to detect the terminal. The pilots may also be used to estimate channel conditions for the terminal, assign the terminal an appropriate base station that may efficiently serve the terminal, and/or for other purposes. The pilot transmitted by the terminal, while useful, also represents overhead.

There is therefore a need in the art for techniques to efficiently transmit pilots on the reverse link.

SUMMARY

Techniques for a terminal to transmit pilot and traffic data on a reverse link are described. In an aspect, a terminal may scramble its pilot with a scrambling sequence generated based on a set of parameters, which may include at least one static parameter and possibly at least one dynamic parameter. The at least one static parameter has a fixed value throughout a communication session of the terminal, can be determined during initial system access of the terminal, and can be independent of a serving sector of the terminal. The at least one dynamic parameter may have a variable value during the communication session and may include a system time parameter. The scrambling sequence may be generated based on the parameter set, for example, by hashing the parameter set to obtain a seed and then initializing a pseudo-random number (PN) generator with the seed. The pilot may then be generated based on the scrambling sequence, e.g., by scrambling pilot data with the scrambling sequence to obtain scrambled pilot data and then generating pilot symbols based on the scrambled pilot data.

In another aspect, the terminal may use different scrambling sequences for pilot and traffic data. The first scrambling sequence may be generated based on a first set of parameters. The pilot may be generated based on a first scrambling sequence and may be transmitted to at least one sector including a serving sector. The second scrambling sequence may be generated based on a second set of parameters. The traffic data may be scrambled based on a second scrambling sequence to obtain scrambled traffic data, which may be sent to the serving sector. The first set may include at least one parameter that is independent of the serving sector. The second set may include at least one parameter dependent on the serving sector. The first and second sets may each include a dynamic parameter, e.g., a system time parameter.

Various aspects and features of the disclosure are described in greater detail below.

Brief Description of Drawings

Fig. 1 shows a wireless communication system.

Fig. 2 shows a superframe structure of a reverse link.

Fig. 3 shows a block diagram of a terminal and two sectors/base stations.

Fig. 4 shows a block diagram of a transmit processor.

Fig. 5 shows a block diagram of a Transmit (TX) pilot processor.

Fig. 6 shows a block diagram of a receive processor.

Fig. 7 shows a process for a terminal to transmit pilots.

Fig. 8 shows an apparatus for transmitting pilots.

Fig. 9 shows a process for a sector/base station to receive pilot.

Fig. 10 shows an apparatus for receiving a pilot.

Fig. 11 shows a process for a terminal to transmit pilot and traffic data.

Fig. 12 illustrates an apparatus for transmitting pilot and traffic data.

Fig. 13 shows a process for a sector to receive pilot and traffic data.

Fig. 14 illustrates an apparatus for receiving pilot and traffic data.

Detailed Description

Fig. 1 shows a wireless communication system 100 with multiple base stations. The wireless system may also be referred to as AN Access Network (AN). The terms "system" and "network" are often used interchangeably. For simplicity, only three base stations 110, 112, and 114 are shown in fig. 1. A base station is a station that communicates with the terminals. A base station may also be called an Access Point (AP), a node B, an evolved node B, etc. Each base station provides communication coverage for a particular geographic area. The term "cell" can refer to a base station and/or its coverage area depending on the context in which the term is used. To increase system capacity, a base station coverage area may be divided into multiple (e.g., three) smaller areas. Each smaller area may be served by a respective base station subsystem. The term "sector" can refer to the smallest coverage area of a base station and/or a base station subsystem that serves this coverage area. The techniques described herein may be used for systems with sectorized cells as well as systems with non-sectorized cells. For clarity, these techniques are described below for a system with sectorized cells. In the following description, the terms "sector" and "base station" are used interchangeably. Base stations 110, 112, and 114 correspond to sectors A, B and C, respectively.

For a centralized architecture, system controller 130 may couple to and provide coordination and control for the base stations. System controller 130 may be a single network entity or a collection of network entities. For a distributed architecture, base stations may communicate with each other as needed.

The terminal 120 may be located anywhere within the system and may be stationary or mobile. Terminal 120 may also be referred to as an Access Terminal (AT), a mobile station, user equipment, a subscriber unit, a station, etc. The terminal 120 can be a cellular telephone, a Personal Digital Assistant (PDA), a wireless communication device, a wireless modem, a handheld device, a laptop computer, a cordless telephone, or the like. A terminal 120 can communicate with zero, one, or multiple sectors on the forward and/or reverse links at any given moment. Terminal 120 can have a serving sector designated for serving terminals on the forward and/or reverse links. Terminal 120 can also have an active set that includes sectors that can serve the terminal. In the example shown in fig. 1, sector a is the serving sector for terminal 120, while sectors B and C are in the active set for terminal 120.

The techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA and SC-FDMA systems. A CDMA system may implement a radio technology such as CDMA2000, Universal Terrestrial Radio Access (UTRA), and so on. OFDMA systems may implement radio technologies such as Ultra Mobile Broadband (UMB), evolved UTRA (E-UTRA), IEEE802.11, IEEE802.16, IEEE802.20, Flash (Flash)And the like. UTRA and E-UTRA are described in the literature from an organization named "third generation partnership project" (3 GPP). cdma2000 and UMB are described in documents from an organization named "third generation partnership project 2" (3 GPP 2). These different radio technologies and standards are well known in the art.

For clarity, certain aspects of these techniques are described below for UMB, and UMB terminology is used in much of the description below. UMB utilizes a combination of Orthogonal Frequency Division Multiplexing (OFDM) and Code Division Multiplexing (CDM). UMB is described in the Specification entitled "Physical Layer Air Interface Specification For Ultra Mobile Broadband (UMB)" entitled Physical Layer For Ultra Mobile Broadband (UMB) "and" Medium Access Control Layer Air Interface Specification For Ultra Mobile Broadband (UMB) "entitled 3GPP2C.S0084-002 both entitled 3GPP2C.S0084-001 and publicly available at 8 months of 2007.

Fig. 2 shows a design of a superframe structure 200 that may be used for the reverse link. The transmission timeline may be divided into units of superframes. Each superframe may span a particular time duration, which may be fixed or configurable. Each superframe may be divided into F physical layer (PHY) frames, where typically F ≧ 1. In one design, F =25, and 25 PHY frames in each superframe are assigned indices 0 through 24. Each PHY frame may cover N OFDM symbol periods, where typically N ≧ 1 and N =8 in one design.

Fig. 2 also shows the subcarrier structure. The system bandwidth may be divided into multiple (K) orthogonal subcarriers, which may also be referred to as tones, bins, etc. The spacing between adjacent subcarriers may be fixed, and the number of subcarriers may depend on the system bandwidth. For example, there may be 128, 256, 512, 1024 or 2048 subcarriers, respectively, for a system bandwidth of 1.25, 2.5, 5, 10 or 20 MHz.

Fig. 2 also shows a design of a CDMA segment that may support transmission of pilot, signaling, and some traffic data on the reverse link. The CDMA segment may support various channels such as, for example, a reverse pilot channel (R-PICH), a reverse CDMA dedicated control channel (R-CDCCH), a reverse access channel (R-ACH), a reverse CDMA data channel (R-CDCH), and so forth.

The CDMA segments may occupy time-frequency resource blocks that may have any dimension. In one design, the CDMA segment includes S CDMA subsegments, where S ≧ 1 in general. Each OFDM sub-segment may cover M adjacent subcarriers in N OFDM symbol periods and may include L = M · N transmission units. A transmission unit may correspond to one subcarrier in one OFDM symbol period. In one design, each OFDM sub-segment covers 128 adjacent subcarriers in 8 OFDM symbol periods of one PHY frame and includes 1024 transmission units. The CDMA segments and subsegments may also have other sizes.

In the design shown in FIG. 2, a CDMA segment is sent in every Q PHY frames, where generally Q ≧ 1, and Q =4, 6, 8, or the like, as some examples. The CDMA segment may hop from CDMA frame to CDMA frame across the system bandwidth (as shown in fig. 2), or may be sent on a fixed set of subcarriers (not shown in fig. 2). The CDMA frame is a PHY frame in which the CDMA segment is transmitted. In general, CDMA segments may be transmitted at any rate and in time-frequency blocks of any dimension. Multiple terminals may share a CDMA segment for pilot, signaling, and so on. This may be more efficient than assigning dedicated time-frequency resources to each terminal to send pilot and signaling on the reverse link.

In an aspect, terminal 120 can transmit a pilot on the reverse link such that the pilot can be designated for reception by all sectors that receive the pilot, e.g., all sectors in the active set of terminal 120. In one design, this may be achieved by scrambling the pilot with a scrambling sequence known to all designated sectors. Terminal 120 can scramble the pilot such that the pilot is unique to terminal 120 among the pilots of all terminals in a given sector. This would then allow the sector to receive and identify pilots from the terminals 120. Further, terminal 120 can scramble pilots such that the pilots are not dedicated to any sector. This will then allow the pilot from terminal 120 to be received by all designated sectors. This would also allow the terminal 120 to transmit the same pilot even if the terminal 120 moves around in the system and hands off between sectors.

In one design, the scrambling sequence for the pilot may be generated based on a set of parameters that may be used to identify terminal 120 and/or minimize collisions with other terminals. In general, any set of parameters may be used to generate the scrambling sequence for the pilot. The set may include only static parameters, or only dynamic parameters, or both static and dynamic parameters. A static parameter is a parameter whose value does not change during a communication session of a terminal, even if the terminal hands off between sectors. The static parameters may also be referred to as session parameters and may be part of the session state information of the terminal. A dynamic parameter is a parameter whose value changes during a communication session.

In one design, the set of parameters for the scrambling sequence for the pilot may include the parameters given in table 1.

TABLE 1 parameters of scrambling sequences for pilots

PilotID may also be referred to as or may include a sector ID, PilotPN (Pilot PN), and the like. Each sector may transmit a pilot on the forward link and may be scrambled with a scrambling sequence assigned to the sector. The PilotPN may be the index of the scrambling sequence used by the sector. Other forms of sector IDs may also be used for the parameter set for the scrambling sequence for the pilot.

The medium access control ID (macid) may also be referred to or may include a terminal ID, a Radio Network Temporary Identifier (RNTI), and the like. Each sector can assign a unique MACID to each terminal in communication with the sector. Each terminal can then be uniquely identified by its assigned MACID for communication with the sector. Terminal 120 can assign a MACID by a given sector upon accessing the sector, upon handing off to the sector, upon adding the sector to an active set, and/or the like. Terminal 120 can use the assigned MACID for the time period that terminal 120 is in communication with the sector. The assigned MACID may be de-assigned when the terminal 120 leaves the sector, when the sector is removed from the active set, and so on. The MACID assigned by the initial access sector may not be valid for communication with other sectors, but may still be used to identify pilots from terminals 120. Other forms of terminal ID may also be used for the parameter set of the scrambling sequence.

The access sequence index may be used to identify the terminal 120 for initial system access prior to assigning the terminal 120 a MACID. The terminal 120 can randomly select an access sequence index and can transmit a corresponding access sequence on the R-ACH to access the system. The access sequence may also be referred to as an access signature, access probe, random access probe, signature sequence, and the like.

The access time may be defined in various ways. For example, the access time may be the time that the terminal 120 sends an access sequence on the reverse link, the time that the sector sends an access grant to the terminal 120 on the forward link, and so on. The access time may also be given in various formats. In one design, the access time may be given by a particular number of least significant bits (e.g., 18 LSBs) of a frame index corresponding to the time at which terminal 120 initially system access. In another design, the access time may be given by a certain number of LSBs (e.g., 9 LSBs) of the superframe index at which the initial system access occurred and a frame index (e.g., 5 or 6 bits) of the superframe frame.

The system time may be the time of transmission and may also be referred to as the current time, the current system time, the time of transmission, and so on. The system time may be given in various formats. In one design, the system time may be given by a particular number of LSBs (e.g., 9 LSBs) of the superframe index at which the transmission occurred and a frame index (e.g., 6 bits) of the superframe frame. The system time may also be given in other formats.

In the design shown in table 1, PilotID, MACID, accesssequence id, and access time may be static parameters, while system time may be a dynamic parameter. The static parameters may be obtained during initial system access and immediately available on both the terminal and the access sector after initial system access is complete. Thus, transmission and reception of pilots can begin once initial system access is complete, and does not require any additional messaging or configuration or any data packet exchange. Static parameters may also be obtained during call setup, hand-offs, etc. The static set of parameters in table 1 may result in a high probability of pilot scrambling uniqueness between different terminals and may reduce the probability of collisions between different terminals.

Table 1 shows an example set of parameters and an example size for each parameter according to a specific design. The parameters in table 1 may have other sizes. Other static and/or dynamic parameters may also be used to generate the scrambling sequence for the pilot. For example, the R-PICH or CDMA sub-segment may hop across the system bandwidth based on a hopping scheme, while the dynamic parameters may be defined based on the frequency resources used for the R-PICH or CDMA sub-segment.

Other combinations of parameters may also be used to generate the scrambling sequence for the pilot. For example, the scrambling sequence may be generated based on (i) a combination of the PilotID, the MACID, and the system time, (ii) a combination of the MACID, the access time, and the system time, or (iii) some other combination of parameters. In another design, the scrambling sequence may be generated based on a static value (e.g., a pseudo-random value) assigned by the initial access sector or selected by terminal 120 and the system time.

Static parameters may be provided for each sector designated to receive pilot from terminal 120, e.g., each new sector added to the terminal's 120 active set. Other session state information may also be communicated to the new sector that was just added to the active set. The dynamic parameters may be known by each sector and may not need to be sent to the new sector.

The set of parameters used to generate the scrambling sequence for the pilot should uniquely identify the terminal 120 with a sufficiently high probability. This may ensure that pilots from both terminals use the same scrambling sequence and that the probability of collision is negligible. A desired uniqueness probability can be achieved by using a sufficient number of parameters with a sufficient number of bits. In general, any set of parameters may be used to uniquely identify the terminal 120 with a sufficiently high probability. The set of parameters can be made available to all designated sectors to enable those sectors to receive pilots from terminals 120. The parameter set may be sent to each new sector via the backhaul or via signaling from terminal 120.

The scrambling sequence for the pilot may be generated based on the set of parameters in various ways. In one design, the parameter set may be used directly as a seed for a PN generator that may implement a particular generator polynomial. In another design, the set of parameters may be hashed with a hash function to obtain a seed for the PN generator. The hash function may map the parameter set to a pseudo-random seed and may provide a seed with fewer bits than the parameter set.

In one design, the set of parameters may include a PilotID (e.g., 10 bits), a MACID (e.g., 11 bits), an access sequence index (e.g., 10 bits), an access time (e.g., 18 bits), and a system time (e.g., 15 bits). This set of parameters may be hashed to obtain a seed (e.g., 20 bits) of the estimated size. Other combinations of parameters and/or parameter sizes may also be used to generate seeds, which may also have other sizes. The size of the seed may be selected based on the desired probability of collision between different terminals. For a 20-bit seed, the probability of two terminals having the same seed is equal to 2^-20It is approximately 10^-6. If there are 1000 terminals in a sector, the probability of a given terminal's scrambling sequence colliding with the scrambling sequences of any remaining terminals is 10^-3. This collision probability may be low enough and may have a negligible impact on system performance.

Using dynamic parameters to generate scrambling sequences may reduce the likelihood of repeated collisions between pilots from two terminals. For example, due to the random nature of the hash function, a first set of static and dynamic parameters of a first terminal may be hashed to the same digest as a second set of static and dynamic parameters of a second terminal, even if the two sets of parameters are different from each other. The dynamic parameter may be a system time that may change for each pilot transmission instance, thereby ensuring that a different set of parameters is input to the hash function. The hash function input varies from pilot transmission instance to pilot transmission instance and further varies from terminal to terminal due to the presence of static parameters. As a result, the hash output is different for each terminal and for each pilot instance, thereby reducing the likelihood of repeated collisions. If the scrambling sequences of two terminals collide in one pilot transmission instance, it is likely that these scrambling sequences will not collide in the next pilot transmission instance. Since the system time is used as one of the inputs to the hash function, at each timeThe probability of collision in one pilot transmission instance may be 10^-6Independent events of (2).

Hashing also allows the scrambling sequence to be derived using a shorter length PN generator, which may simplify implementation. The PN generator may be initialized with a seed and then operated to generate a scrambling sequence for the pilot.

The pilot from terminal 120 may be used for various purposes. Serving sector 110 can use the pilot as a reference signal to estimate the received signal quality for the corresponding terminal 120. Serving sector 110 may determine a Power Control (PC) command based on the received signal quality and may send the PC command to terminal 120 on a forward power control channel (F-PCCH). Terminal 120 can adjust its transmit power or transmit power density (PSD) based on PC commands. The pilot from terminal 120 may thus be used as a reference to set the power level at which terminal 120 transmits data and control channels.

All sectors in the active set of terminal 120 can receive pilots from terminal 120 and determine the strength of the received pilots. Each sector in the active set may determine a Pilot Quality Indicator (PQI) based on the received pilot strength and may transmit the PQI on the forward PQI channel (F-PQICH) to the terminal 120. Terminal 120 can use the PQI from all sectors in the active set to determine which sector has the best reverse link (e.g., the highest received pilot strength) for terminal 120 and can use this information to make a decision to handoff on the reverse link.

Terminal 120 can also scramble traffic data sent to the serving sector and can use a scrambling sequence that is specific to the serving sector. In one design, the scrambling sequence for traffic data may be generated based on the set of parameters set forth in table 2.

Table 2-parameters of scrambling sequences for traffic data

Parameter(s)	Length of	Description of the invention
			PilotID	10 bit	The ID of the serving sector for terminal 120.

MACID	11 bits	The ID assigned to terminal 120 by the serving sector.
			System time	10 bit	The time at which the terminal 120 transmits traffic data.

The PilotID and MACID in table 2 are related to the serving sector and may be different from the PilotID and MACID related to the initial access sector in table 1. Such a situation may exist if terminal 120 has handed off from an initial access sector to a current serving sector. The system time may be given in various formats. In one design, the system time may be given by 4 LSBs of a superframe index or a 6-bit frame index of a frame within a superframe in which traffic data is transmitted.

Table 2 shows an example parameter set and an example size for each parameter according to a particular design. These parameters may have other sizes. Other parameters may also be used to generate the scrambling sequence for traffic data. For example, a packet format index of a packet may be used as a parameter for a scrambling sequence for traffic data. Other combinations of parameters may also be used for the scrambling sequence of traffic data.

Fig. 3 shows a block diagram of a design of terminal 120, serving sector/base station 110, and active set sector/base station 112 in fig. 1. At terminal 120, a transmit processor 320 may receive traffic data from a data source 312 and signaling from a controller/processor 330. Transmit processor 320 may process (e.g., encode, interleave, and symbol map) the traffic data, signaling, and pilot and provide data symbols, signaling symbols, and pilot symbols, respectively. As used herein, a data symbol is a symbol corresponding to traffic data, a signaling symbol is a symbol corresponding to signaling or control information, a pilot symbol is a symbol corresponding to pilot, and a symbol is typically a complex value. A Modulator (MOD) 322 may perform modulation on the data, signaling, and pilot symbols (e.g., for OFDM) and provide output chips. Each chip may be a complex value in the time domain. A transmitter (TMTR) 324 may condition (e.g., convert to analog, amplify, filter, and upconvert) the output chips and generate a reverse link signal, which may be transmitted via an antenna 326.

At serving sector 110, an antenna 352a can receive reverse link signals from terminal 120 and other terminals. A receiver (RCVR) 354a may condition (e.g., filter, amplify, downconvert, and digitize) the signal received from antenna 325a and provide samples. A demodulator (DEMOD) 356a may perform demodulation on the samples (e.g., for OFDM) and provide symbol estimates. A receive processor 360a may process (e.g., symbol demap, deinterleave, and decode) the symbol estimates, provide decoded data to a data sink 362a, and provide decoded signaling to a controller/processor 370 a.

Sector 112 can similarly receive and process reverse link signals from terminal 120 and other terminals. The received signal from antenna 352b may be conditioned by a receiver 354b, demodulated by a demodulator 356b, and processed by a receive processor 360 b.

On the reverse link, a transmit processor 382a at the serving sector 110 may receive and process data from a data source 380a as well as signaling (e.g., PC commands, PQI, etc.) from the controller/processor 370 a. A modulator 384a may perform modulation on the data, signaling, and pilot symbols from transmit processor 382a and provide output symbols. Transmitter 386a may condition the output chips and generate a forward link signal, which may be transmitted via an antenna 352 a. Sector 112 can similarly process and transmit traffic data, signaling, and pilot to terminals within its coverage area.

At terminal 120, the forward link signals from sectors 110 and 112, as well as other sectors, can be received by antennas 326, conditioned by receivers 340, demodulated by a demodulator 342, and processed by a receive processor 344. Processor 344 may provide decoded data to a data sink 346 and decoded signaling to controller/processor 330.

Controllers/processors 330, 370a, and 370b may direct the operation at terminal 120 and sectors 110 and 112, respectively. Memories 332, 372a and 372b may store data and program codes for terminal 120 and sectors 110 and 112, respectively. Schedulers 374a and 374b may schedule terminals for communication with sectors 110 and 112, respectively, and may assign channels and/or time-frequency resources to the terminals.

Fig. 4 shows a block diagram of a design of transmit processor 320 at terminal 120 in fig. 3. In this design, transmit processor 320 includes a TX pilot processor 410 and a TX data processor 420.

Within TX pilot processor 410, a generator 412 may receive a set of parameters, e.g., the parameters in table 1, for a scrambling sequence for a pilot. Generator 412 may generate a scrambling sequence for the pilot based on the received set of parameters. A scrambler 414 may scramble pilot data with the scrambling sequence from generator 412 and provide scrambled pilot data. The pilot data may be any known data, such as an orthogonal sequence, a full 1 sequence, a known PN sequence, and so on. Generator 416 may generate pilot symbols based on the scrambled pilot data and provide the pilot symbols to modulator 322.

Within TX data processor 420, a generator 422 may receive a set of parameters, e.g., the parameters in table 2, for a scrambling sequence for traffic data. Generator 422 may generate a scrambling sequence for traffic data based on the received set of parameters. Encoder and interleaver 424 may receive and encode packets of traffic data to obtain encoded packets and may further interleave bits in the encoded packets based on an interleaving scheme. A scrambler 426 may scramble bits from interleaver 424 to randomize the data. Symbol mapper 428 may map the scrambled traffic data to data symbols based on the selected modulation scheme.

Fig. 5 shows a block diagram of a design of TX pilot processor 410 in fig. 4. Within scrambling sequence generator 412, a set of parameters, such as those in Table 1, for the scrambling sequence for the pilot may be received and linked by a multiplexer (Mux) 512. The hash function 514 may receive and hash the linked set of parameters and provide a hash digest. The hash digest may have a fixed size (e.g., 20 bits) and may be used as a seed for the PN generator 516. The PN generator 516 may be initialized with a seed and may provide a pseudo-random chip sequence as a scrambling sequence. Within scrambler 414, a multiplier 522 may perform a chip-by-chip multiplication of pilot data with a scrambling sequence and provide scrambled pilot data. In one design, the pilot data is an L1 sequence, the scrambling sequence is an L chip pseudorandom sequence, and the scrambled pilot data is an L chip pseudorandom sequence. The pilot data may also be other orthogonal sequences or other known data.

Within pilot symbol generator 416, a multiplier 532 may scale each chip from scrambler 414 with the gain of the R-PICH. Interleaver 534 may change the order of the chip sequences from multiplier 532. In one design, the pilot is transmitted in a CDMA subsegment for M subcarriers in N OFDM symbol periods, as shown in fig. 2. Unit 536 may divide the sequence of chips from interleaver 534 into N subsequences, where each subsequence includes M chips. In each OFDM symbol period of the CDMA subsegment, a Discrete Fourier Transform (DFT) unit 538 may perform an M-point DFT on M chips in the subsequence for that OFDM symbol period and provide M pilot symbols for the N subcarriers in the OFDM symbol period.

As described above, multiple terminals may transmit different channels in the same CDMA subsegment using CDM. The terminal 120 can log by (i)₂An L bit value is mapped to the L chip Walsh sequence and (ii) the L chip Walsh sequence is scrambled with the L chip scrambling sequence to obtain an L chip pseudo-random sequence to transmit the value on a channel in the CDMA subsegment. This pseudo-random sequence may be superimposed with pseudo-random sequences from other terminals and/or other channels in the CDMA subsegment. This superposition constitutes CDM.

Scrambling sequence generator 422 and scrambler 426 of TX data processor 420 in fig. 4 may be implemented in the same manner as scrambling sequence generator 412 and scrambler 414, respectively, in fig. 5. However, the hash function within scrambling sequence generator 422 may generate the seed based on a different set of parameters for the traffic data, such as the parameters in table 2.

A sector may receive pilots from any number of terminals. A sector can have a set of parameters corresponding to a scrambling sequence for a pilot for each terminal to be received by the sector. The sector may receive the pilot transmitted by each terminal and process the pilot based on the scrambling sequence used for the pilot by the terminal.

FIG. 6 shows a block diagram of a design of a receive processor 360 that may be used for receive processors 360a and 360b in FIG. 3. Receive processor 360 includes a Receive (RX) pilot processor 610 and an RX data processor 630.

Within RX pilot processor 610, a pilot symbol processor 612 may obtain received symbols for the CDMA subsegments and may process the received symbols in a manner complementary to the processing by pilot symbol generator 416 of FIG. 5. Processor 612 may perform an M-point inverse fourier transform (IDFT) on the M received symbols in each OFDM symbol period to obtain M input samples. Processor 612 may then assemble the input samples within the N OFDM symbol periods of the CDMA subsegment to obtain a sequence of L input samples.

Scrambling sequence generator 614 may generate a scrambling sequence for a pilot for a terminal 120 based on a set of parameters used by the terminal 120 for the pilot. Generator 614 may be implemented with generator 412 in fig. 5. A descrambler 616 may descramble the input sequence of samples with the scrambling sequence and provide a descrambled sequence. Pilot correlator 618 may correlate the descrambled sequence with pilot data. Energy accumulator 620 may accumulate the energy of all samples from pilot correlator 618. The pilot from terminal 120 may be received via one or more signal paths. RX pilot processor 610 may perform processing for each signal path of interest and then combine the energies of all signal paths to obtain a received pilot strength for the corresponding terminal 120. PQI generator 622 can obtain the received pilot strength and determine the PQI for the corresponding terminal 120. Estimator 624 may estimate the received signal quality for corresponding terminal 120. The generator 626 may generate PC commands for the corresponding terminal 120 based on the received signal quality. The PC command and the PQI may be transmitted to the terminal 120.

RX data processor 630 may process the received traffic data symbols in a manner complementary to the processing by TX data processor 420 in fig. 4. Processor 630 may generate a scrambling sequence for the traffic data based on a set of parameters used by terminal 120 for the traffic data. Processor 630 may then perform descrambling of the traffic data with this scrambling sequence.

Fig. 7 shows a design of a process 700 for terminal 120 to transmit pilot. A scrambling sequence may be generated based on a set of parameters including at least one static parameter and possibly at least one dynamic parameter (block 712). The at least one static parameter has a fixed value throughout the communication session of the terminal. The at least one static parameter may be determined during initial system access for the terminal and may be independent of a serving sector for the terminal. The at least one static parameter may include at least one of an ID of a sector initially accessed by the terminal, an ID assigned to the terminal by the initial access sector, an access sequence index used by the terminal for initial system access, and an initial system access time of the terminal. The at least one dynamic parameter has a variable value during the communication session and may include a system time parameter. The system time parameters may include a superframe index of the superframe in which the pilot is transmitted and/or a frame index of the frame within the superframe in which the pilot is transmitted. For block 712, the parameter set may be hashed to obtain a seed, and a scrambling sequence may be generated based on the seed.

A pilot may be generated based on the scrambling sequence (block 714). For block 714, the pilot data may be scrambled with a scrambling sequence to obtain scrambled pilot data. Pilot symbols may be generated based on the scrambled pilot data and may be mapped to time frequency blocks used to transmit pilots. The pilot data may comprise orthogonal sequences or some other known data. The pilot may comprise pilot symbols. The time frequency blocks may correspond to CDMA subsegments used by different terminals to transmit pilot and/or other information on the reverse link.

The pilot may be transmitted to at least one sector including the serving sector for the terminal (block 716). At least one sector may be in an active set of a terminal. The PC command determined based on the pilot may be received from the serving sector (block 718). The transmit power of the terminal may be adjusted based on the PC commands (block 720). A PQI determined based on the pilot may be received from each of the at least one sector (block 722). One of the at least one sector may be selected as a serving sector based on the PQI received from each sector (block 724). The terminal may handoff from the serving sector to the new serving sector. The same set of parameters may be used to generate the scrambling sequence for the pilot sent to the new serving sector.

Fig. 8 shows a design of an apparatus 800 for transmitting pilots. The apparatus 800 comprises: means for generating a scrambling sequence based on a set of parameters including at least one static parameter and possibly at least one dynamic parameter (block 812); means for generating a pilot based on the scrambling sequence (module 814); means for transmitting a pilot to at least one sector including a serving sector for a terminal (block 816); means for receiving a pilot determination-based PC command from a serving sector (block 818); means for adjusting a transmit power of the terminal based on the PC command (block 820); means for receiving a PQI determined based on a pilot from each of at least one sector (block 822); and means for selecting one of the at least one sector as a serving sector based on the PQI received from each sector (block 824).

Fig. 9 shows a design of a process 900 for a sector to receive pilot. The pilot may be received from a terminal, e.g., from a time frequency block used to transmit the pilot on the reverse link (block 912). A scrambling sequence for the terminal may be generated based on a set of parameters including at least one static parameter and possibly at least one dynamic parameter (block 914). The parameter set may be hashed to obtain a seed, and a scrambling sequence may be generated based on the seed. The received pilot may be descrambled with the scrambling sequence to obtain a descrambled pilot for the terminal (block 916).

A received pilot strength for the corresponding terminal may be determined based on the descrambled pilots (block 918). A PQI may be generated based on the received pilot strength (block 920) and transmitted to the terminal (block 922). If the sector is the serving sector for the terminal, the received signal quality for the corresponding terminal may be determined based on the descrambled pilot (block 924). A PC command may be generated based on the received signal quality (block 926) and transmitted to the terminal (block 928).

Fig. 10 shows a design of an apparatus 1000 for receiving pilots. The apparatus 1000 comprises: means for receiving a pilot from a terminal (module 1012); means for generating a scrambling sequence for the terminal based on a set of parameters comprising at least one static parameter and possibly at least one dynamic parameter (module 1014); means for descrambling the received pilot with the scrambling sequence to obtain a descrambled pilot for the terminal (module 1016); means for determining a received pilot strength for a corresponding terminal based on the descrambled pilots (module 1018); means for generating a PQI based on the received pilot strength (module 1020); means for transmitting the PQI to the terminal (block 1022); means for determining a received signal quality for a corresponding terminal based on the descrambled pilot (module 1024); means for generating PC commands based on the received signal quality (block 1026); and means for sending the PC command to the terminal (block 1028).

Fig. 11 shows a design of a process 1100 for a terminal 120 to transmit pilot and traffic data. A first scrambling sequence may be generated based on a first set of parameters (block 1112). The first set of parameters may be hashed to obtain a first seed, and a first scrambling sequence may be generated based on the first seed. A pilot may be generated based on the first scrambling sequence (block 1114). The pilot may be transmitted to at least one sector including the serving sector for the terminal (block 1116).

A second scrambling sequence may be generated based on a second set of parameters (block 1118). The second set of parameters may be hashed to obtain a second seed, and a second scrambling sequence may be generated based on the second seed. The traffic data may be scrambled based on the second scrambling sequence to obtain scrambled traffic data (block 1120). The scrambled traffic data may be sent to the serving sector (block 1122).

The first set may include at least one parameter that is independent of the serving sector. The first set may include at least one of an ID of a sector initially accessed by the terminal, an ID assigned to the terminal by the initial access sector, an access sequence index used by the terminal for initial system access, and an initial system access time of the terminal. The second set may include at least one parameter dependent on the serving sector. The second set can include at least one of an ID of the serving sector and an ID assigned to the terminal by the serving sector. The first and second sets may each include a system time parameter that may include (i) a superframe index of a superframe in which pilot or traffic data is transmitted and/or (ii) a frame index of a frame within the superframe in which pilot or traffic data is transmitted. The first and second sets may also include other parameters.

Fig. 12 shows a design of an apparatus 1200 for transmitting pilot and traffic data. The apparatus 1200 includes: means for generating a first scrambling sequence based on a first set of parameters (module 1212); means for generating a pilot based on the first scrambling sequence (module 1214); means for transmitting a pilot to at least one sector including a serving sector for a terminal (block 1216); means for generating a second scrambling sequence based on a second set of parameters (block 1218); means for scrambling traffic data based on the second scrambling sequence to obtain scrambled traffic data (module 1220); and means for transmitting the scrambled traffic data to the serving sector (block 1222).

Fig. 13 shows a design of a process 1300 for a sector to receive pilot and traffic data. A pilot may be received from a terminal (block 1312). A first scrambling sequence may be generated based on a first set of parameters, which may include any of the parameters in table 1 (block 1314). The first set of parameters may be hashed to obtain a first seed, and a first scrambling sequence may be generated based on the first seed. The received pilot may be descrambled with a first scrambling sequence to obtain a descrambled pilot (block 1316).

Traffic data may be received from the terminal (block 1318). A second scrambling sequence may be generated based on a second set of parameters, which may include any of the parameters in table 2 (block 1320). The second set of parameters may be hashed to obtain a second seed, and a second scrambling sequence may be generated based on the second seed. The received traffic data may be descrambled with the second scrambling sequence to obtain descrambled traffic data (block 1322).

Fig. 14 shows a design of an apparatus 1400 for receiving pilot and traffic data. The apparatus 1200 includes: means for receiving a pilot from a terminal (module 1412); means for generating a first scrambling sequence based on a first set of parameters (module 1414); means for descrambling a received pilot with a first scrambling sequence to obtain a descrambled pilot (module 1416); means for receiving traffic data from a terminal (block 1418); means for generating a second scrambling sequence based on a second set of parameters (block 1420); and means for descrambling the received traffic data with the second scrambling sequence to obtain descrambled traffic data (block 1422).

The modules in fig. 8, 10, 12, and 14 may comprise processors, electronics devices, hardware devices, electronic components, logic circuits, memories, etc., or any combination thereof.

The techniques described herein may be implemented by various means. For example, these techniques may be implemented in hardware, firmware, software, or a combination thereof. For a hardware implementation, the processing units used to perform the techniques at an entity (e.g., a terminal or a base station) may be implemented within one or more Application Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, micro-controllers, microprocessors, electronic devices, other electronic units designed to perform the functions described herein, a computer, or a combination thereof.

For a firmware and/or software implementation, the techniques may be implemented with code (e.g., procedures, functions, modules, instructions, etc.) that performs the functions described herein. In general, any computer/processor readable medium tangibly embodying firmware and/or software code may be used to implement the techniques described herein. For example, these firmware and/or software codes may be stored in a memory (e.g., memory 332, 372a or 372b in fig. 3) and executed by a processor (e.g., processor 330, 370a or 370 b). The memory may be implemented within the processor or external to the processor. The firmware and/or software codes may also be stored in a computer/processor readable medium such as Random Access Memory (RAM), read-only memory (ROM), non-volatile random access memory (NVRAM), programmable read-only memory (PROM), electrically erasable PROM (eeprom), flash memory, floppy disks, Compact Disks (CDs), Digital Versatile Disks (DVDs), magnetic or optical data storage devices, etc. The code may be executed by one or more computers/processors and may cause the computers/processors to perform certain aspects of the functionality described herein.

The previous description of the disclosure is provided to enable any person skilled in the art to make or use the disclosure. Various modifications to the disclosure will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the disclosure. Thus, the disclosure is not intended to be limited to the examples and designs described herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (22)

1. An apparatus for wireless communication, comprising:

at least one processor configured to generate a first scrambling sequence based on a first set of parameters, generate a pilot based on the first scrambling sequence, transmit the pilot to at least one sector including a serving sector for a terminal, generate a second scrambling sequence based on a second set of parameters different from the first set of parameters, scramble traffic data based on the second scrambling sequence to obtain scrambled traffic data, and transmit the scrambled traffic data to the serving sector, wherein at least one of the first set of parameters and the second set of parameters includes a system time parameter indicating a time at which the pilot or the traffic data is transmitted; and

a memory coupled to the at least one processor.

2. The apparatus of claim 1, wherein the at least one processor is configured to hash the first set of parameters to obtain a first seed, to generate the first scrambling sequence based on the first seed, to hash the second set of parameters to obtain a second seed, and to generate the second scrambling sequence based on the second seed.

3. The apparatus of claim 1, wherein the first set comprises at least one parameter that is independent of the serving sector, and wherein the second set comprises at least one parameter that is dependent on the serving sector.

4. The apparatus of claim 1, wherein at least one of the first and second sets comprises a system time parameter.

5. The apparatus of claim 4, wherein the system time parameter comprises a superframe index of a superframe in which pilot or traffic data is sent and/or a frame index of a frame in which the pilot or traffic data is sent.

6. The apparatus of claim 1, wherein the first set of parameters comprises an Identifier (ID) of a sector initially accessed by the terminal, or an ID assigned to the terminal by the initial access sector, or an access sequence index used by the terminal for initial system access, or a time of the initial system access by the terminal, or a combination thereof.

7. The apparatus of claim 1, wherein the second set of parameters comprises an Identifier (ID) of the serving sector and/or an ID assigned to the terminal by the serving sector.

8. A method for wireless communication, comprising:

generating a first scrambling sequence based on a first set of parameters;

generating a pilot based on the first scrambling sequence;

transmitting the pilot to at least one sector including a serving sector for a terminal;

generating a second scrambling sequence based on a second set of parameters different from the first set of parameters;

scrambling traffic data based on the second scrambling sequence to obtain scrambled traffic data; and

transmitting the scrambled traffic data to the serving sector,

wherein at least one of the first set of parameters and the second set of parameters includes a system time parameter indicating a time at which the pilot or the traffic data is transmitted.

9. The method of claim 8, wherein the generating the first scrambling sequence comprises hashing the first set of parameters to obtain a first seed, and generating the first scrambling sequence based on the first seed, and wherein the generating the second scrambling sequence comprises hashing the second set of parameters to obtain a second seed, and generating the second scrambling sequence based on the second seed.

10. The method of claim 8, wherein at least one of the first and second sets comprises a system time parameter.

11. The method of claim 8, wherein the first set comprises at least one parameter that is independent of the serving sector, and wherein the second set comprises at least one parameter that is dependent on the serving sector.

12. The method of claim 10, wherein the system time parameter comprises a superframe index of a superframe in which pilot or traffic data is transmitted and/or a frame index of a frame in which the pilot or traffic data is transmitted.

13. The method of claim 8, wherein the first set of parameters comprises an Identifier (ID) of a sector initially accessed by the terminal, or an ID assigned to the terminal by the initial access sector, or an access sequence index used by the terminal for initial system access, or a time of the initial system access by the terminal, or a combination thereof.

14. The method of claim 8, wherein the second set of parameters comprises an Identifier (ID) of the serving sector and/or an ID assigned to the terminal by the serving sector.

15. An apparatus for wireless communication, comprising:

at least one processor configured to receive a pilot from a terminal, to generate a first scrambling sequence based on a first set of parameters, to descramble the received pilot with the first scrambling sequence to obtain a descrambled pilot, to receive traffic data from the terminal, to generate a second scrambling sequence based on a second set of parameters different from the first set of parameters, and to descramble the received traffic data with the second scrambling sequence to obtain descrambled traffic data, wherein at least one of the first and second sets of parameters comprises a system time parameter indicating a time at which the pilot or the traffic data is transmitted; and

a memory coupled to the at least one processor.

16. The apparatus of claim 15, wherein the at least one processor is configured to hash the first set of parameters to obtain a first seed, to generate the first scrambling sequence based on the first seed, to hash the second set of parameters to obtain a second seed, and to generate the second scrambling sequence based on the second seed.

17. The apparatus of claim 15, wherein the first set comprises at least one parameter that is independent of a serving sector for the terminal, and wherein the second set comprises at least one parameter that is dependent on the serving sector.

18. The apparatus of claim 15, wherein at least one of the first and second sets comprises a system time parameter.

19. A method for wireless communication, comprising:

receiving a pilot from a terminal;

generating a first scrambling sequence based on a first set of parameters;

descrambling the received pilot with the first scrambling sequence to obtain a descrambled pilot;

receiving traffic data from the terminal;

generating a second scrambling sequence based on a second set of parameters different from the first set of parameters; and

descramble the received traffic data with the second scrambling sequence to obtain descrambled traffic data,

wherein at least one of the first set of parameters and the second set of parameters includes a system time parameter indicating a time at which the pilot or the traffic data is transmitted.

20. The method of claim 19, wherein the generating the first scrambling sequence comprises hashing the first set of parameters to obtain a first seed, and generating the first scrambling sequence based on the first seed, and wherein the generating the second scrambling sequence comprises hashing the second set of parameters to obtain a second seed, and generating the second scrambling sequence based on the second seed.

21. The method of claim 19, wherein the first set comprises at least one parameter that is independent of a serving sector for the terminal, and wherein the second set comprises at least one parameter that is dependent on the serving sector.

22. The apparatus of claim 19, wherein at least one of the first and second sets comprises a system time parameter.