Method for compensating for multi-path of a cdma reverse link utilizing an orthogonal channel structure

Compensating the use of orthogonal channel structure CDMA reverse link multi-path method

METHOD FOR COMPENSATING FOR MULTI-PATH OF A CDMA REVERSE LINK UTILIZING AN ORTHOGONAL CHANNEL STRUCTURE

The present invention is related to a CDMA reverse connection multipath method, and more particularly to a CDMA reverse connection multipath method that compensates the use of an orthogonal channel structure.

In the past two decades, there has been unprecedented growth in both the type and demand of wireless communication services. Wireless voice communication services including mobile phones, personal communication services (PCS) and similar systems provide almost ubiquitous coverage today. The infrastructure of these networks has been popularized in the United States and Europe where most residents are located, and there are more than one developed regions in the world, but there are multiple service providers to choose from.

The continued growth of the electronics and computer industries has greatly promoted the demand for Internet access and the many services and features it provides. This increase in the use of computer equipment, especially portable types including laptops, handheld personal digital assistants (PDAs), Internet-enabled mobile phones, and similar devices, has led to problems with wireless data access There is a corresponding increase in demand.

Although mobile phones and PCS networks have been widely deployed, these systems are not originally expected to be used to carry data streams. In fact, these networks are designed to efficiently support continuous analog signals instead of the burst mode digital communication protocols required for Internet communication. It is also considered that a communication bandwidth of about 3 kilohertz (kHz) is sufficient for voice communication. However, it is generally accepted that for effective Internet communications, such as World Wide Web (Web) browsing, a data transfer rate of at least 56 kilobits per second (kbps) or higher is necessary.

In addition, the peculiar nature of the data stream itself is very different from the nature of voice communication. Sound requires a continuous full-duplex connection; that is, a user at one end of a connection wants to be able to continuously transmit and receive to a user at the other end of the connection. At the same time, the user at the other end can also transmit and receive. However, on the whole, accessing web pages through the Internet is very cluster-oriented. Generally speaking, the use of a remote user's computer specifies the address of a computer file on a World Wide Web server, for example. The request is then formatted into a shorter data message, usually less than 1000 bytes in length. Then, the other end of the connection, such as one of the World Wide Web servers on the Internet, replies with the requested data file, which can be text, pictures, audio, and video ranging from 10 kilobytes to millions of bytes. Data, or a combination of the above. Because of the inherent latency of the Internet, users often expect a delay of at least a few seconds or more before the requested content starts to be sent. And once the content is sent, the user may spend a few seconds or even minutes reviewing and reading the content of the web page before specifying the next web page to be downloaded.

Furthermore, the voice network is constructed to support high-mobility use; that is, the use of extremely long lengths to support highway-speed-level movement allows users of voice-based mobile networks and PCS networks to move at high speeds at high speeds. Maintain the connection while the road is moving. However, a typical user of a laptop computer is relatively static, such as sitting at a table. Therefore, the inter-cell and intra-cell high-speed movement that must be carefully considered for wireless voice networks is usually not necessary to support data access.

It is reasonable to refurbish certain components of the existing wireless infrastructure to coordinate wireless data more efficiently. The additional functions implemented for new types of users with high data transmission rates but low mobility should be downward compatible with existing functions for users with low data transmission rates and high mobility. This permits the use of the same frequency allocation plan, base station antennas, build out sites, and other aspects of the existing voice network infrastructure that are used to provide new high-speed data services.

It is particularly important to support a data transmission rate as high as possible on the reverse link of the network that carries data on the reverse link (for example, from the remote unit to the base station). Imagine that existing digital cellular standards such as IS-95 code division multi-directional access (CDMA) require different code sequences to be used in a forward connection direction to maintain Support the minimum interference between channels. In particular, this system uses orthogonal codes on the forward link, which define individual logical channels. However, the optimal operation of this system requires that all these codes be time calibrated to a specified boundary to maintain orthogonality at the receiver. Therefore, the transmission must be synchronized.

This is not particularly critical in a forward link direction, because all transmissions originate from the same place, that is, at a base transceiver station. But at present, the digital cellular CDMA standard does not attempt to use or require orthogonality between channels in a reverse link direction. It is generally believed that it is too difficult to synchronize the transmission of remote units that originate from different locations and are likely to be far from the base station. In fact, these systems usually use a chip-level scrambling code with a unique shift of the long pseudo-random code that is sufficient to distinguish individual reverse link channels. However, the use of this scrambling will therefore exclude the possibility that the transmissions of different users are orthogonal to each other.

Therefore, one embodiment of the present invention includes a system that supports communication between members of a first user group and a second user group. The first user group can be old users of a digital code division multi-directional access (CDMA) mobile phone system, which encode their transmissions with a common first code. This first user group can be uniquely recognized by providing a unique code phase offset for each user. The second user group may be users of a high-speed data service that use the same code to encode their transmission and share one of the code phase shifts of the code. However, each user in the second group further encodes its transmission with an additional code, which is unique for each user in the second group. This allows the transmission of the second user group to be orthogonal to each other, while still maintaining the appearance of collectively being a single user of the first group.

The code assigned to the first user group can be a common chipping rate or pseudo-random code. The codes assigned to the second terminal group can usually be a set of unique orthogonal codes. The individual members of the first terminal group can be distinguished by a scramble code with a unique phase shift of a selected longer pseudo-random noise sequence do not.

In a preferred embodiment, certain steps are taken to ensure the correct operation of the mailing or the so-called "heartbeat" in the second user group. In particular, a common code channel can be designated as a synchronization channel. For example, when the coding scheme is implemented in a reverse link direction, it will allow the correct timing of the transmission of the second terminal group to be maintained.

In another embodiment, users of the second group can be assigned a designated transmission time slot and thus maintain orthogonality through the use of time-sharing multi-directional access. Also, the point is that users in the second group collectively behave as a single user to the transmission of users in the first group.

Due to the orthogonal signaling, the principle of the present invention allows a CDMA system with only one antenna in a multipath environment to make a diversity decision, because the unique orthogonal code can be divided into two or more different phases. See. In a preferred embodiment, for a signal received in multiple phases from a known field unit in the second group in a multipath environment, a base station selects one of the phases A "best" connection signal is reversed to make a diversity decision. The reverse link signal in the selected phase is calibrated orthogonally to the reverse link signals of other field units in the selected group. The orthogonal calibrated reverse link signal may be referred to as an orthogonal link in this specification, and it is in a reverse link that is not orthogonally calibrated to the signals of other field units in the second group. The signal can be referred to as a non-orthogonal link in this specification.

Since an orthogonal link must be time calibrated to maintain orthogonality from one user to the next, a timing control loop is used from the base station to keep the reverse link signal in the selected phase aligned orthogonally Reverse connection signals of other field units in the second group.

The existing CDMA system defines the reverse link channelization non-orthogonally. This is done by defining the unique scatter code shift for each reverse link user. Orthogonal and non Orthogonal downward compatibility can be achieved by orthogonal users who share the same scatter code with one of the main base stations. When these user signals are received at other base stations, they are unlikely to be time-aligned, but they will have unique code shifts and can be uniquely identified based on the combination of code shifts and orthogonal codes .

When diversity selection occurs and the code phase of the reverse link signal is shifted, there may be a significant code phase shift. Using a conventional unit cell differential timing control loop may be too slow to quickly obtain orthogonality with the reverse connection signal from other field units. Therefore, when diversity selection occurs, a total timing adjustment command or message can be used to quickly recalibrate the reverse link. The total timing adjustment can be an absolute or relative value. In the case of a timing command, the field unit is told to perform a coarse timing adjustment; in the case of a timing message, the subscriber unit autonomously responds to the information in the timing message.

The criteria for timing control selection (that is, diversity selection) may be based on criteria that include at least one of the following: 1. The metric of an alternative path exceeds a threshold of a specified period of time; 2. One time (that is, The metric of the unselected path exceeds a threshold relative to the current path in a specified period of time; 3. The primary (that is, the currently selected) path falls below an absolute metric; or 4. The secondary path exceeds an absolute Metric, where the metric can be one or more of the following: a. Power; b. SNR; c. Variable of power; d. Variable of SNR; or e. The above metric between the primary path and the secondary path Relative ratio.

The preferred embodiments of the present invention will be described below.

Figure 1 is a block diagram of a code division multidirectional access (CDMA) communication system 10, which uses a signal coding architecture in which the first level of logic channels are assigned to unique long codes with different code phase offsets And the second-level logical channel is provided by using a common long code and a common code phase offset, combined with an additional encoding procedure that uses a unique orthogonal code for each channel.

In the following detailed description of a preferred embodiment, the communication system 10 is described on the premise that the shared channel resource is a wireless or radio channel. However, it should be understood that the technology described in this manual can be applied to implement shared access to other types of media, such as telephone connections, computer network connections, cable connections, or may be allowed on a demand-driven basis Other physical media accessed.

The system 10 supports the first user group 110 and the second user group 210. The first user group 110 is usually old users of mobile phone devices such as wireless phones 113-1, 113-2 and/or cellular mobile phones 113-h installed in vehicles. In principle, the first user group 110 uses the network in an audio mode, thereby encoding its communication into continuous transmission. In a preferred embodiment, these user transmissions are sent from the subscriber unit 113 through the forward link 40 radio channel and the reverse link 50 radio channel. The signal is managed in a central location, which includes a base station antenna 118, a base transceiver station (BTS) 120, and a base station controller (BSC) 123. Therefore, the first user group 110 usually uses the mobile subscriber unit 113, the BTS 120, and the BSC 123 to conduct voice conversations to connect to the telephone connection through the public switched telephone network (PSTN) 124.

The forward link 40 used by the first user group can be coded according to a well-known digital cellular standard, such as the code division multidirectional access (CDMA) standard defined in IS-95B specified by the Telecommunications Industry Association (TIA). The forward link 40 includes at least one call channel 141 and one traffic channel 142, as well as other logical channels 144. These forward links 40, the old channels 141, 142, and 144 are used in this system by Defined using orthogonal coded channels. The first user group 110 also encodes its transmission on the reverse link 50 according to the IS-95B standard. Therefore, several logical channels are used in the direction of a reverse link 50, including an incoming channel 151, a traffic channel 152, and other logical channels 154. In this reverse link 50, the first user group 110 usually encodes its signals with a common long code using different code phase offsets. The way the old user 110 encodes his signal on the reverse link 50 is also well known in this art.

The communication system 10 also includes a second user group 210. The second user group 210 is usually users who need high-speed wireless data services. Its system components include several remote personal computer (PC) devices 212-1, 212-2, ... 212 corresponding to remote user access units (SAUs) 214-1, 214-2, ... 214-h -h, and related antennas 216-1, 216-2, ... 216-h. The central device includes a base station antenna 218 and a base station processor (BSP) 220. The BSP 220 provides connections to and from an Internet gateway 222, which provides access to a data network such as the Internet 224 and a network file server 230 connected to the network 222. It should be understood that the BTS 120 can be retrofitted to operate in the same manner as the BSP 220 and provide similar connections to and from an Internet gateway 222. Therefore, in some embodiments, the SAUs 214 can communicate with the BSP 220 or the BTS 120 regarding the forward link 40 and the reverse link 50.

The PCs 212 can transmit data to and receive data from the network server 230 through the two-way wireless connection to the link 40 and the reverse link 50 used by the old user 110. It should be understood that in a point-to-multipoint multi-directional access wireless communication system 10 as shown in the figure, a known base station processor 220 supports multiple different effective users in a manner similar to a mobile phone communication network. The access unit 214 communicates.

In the current situation, the radio frequency allocated to the first group 110 is the same as the user allocated to the second group 210. One aspect of the present invention pays special attention to how to allow a different coding structure to be used by the second group 210 while simultaneously applying to the first group 210. Group 110 causes minimal interference.

The PCs 212 are usually laptop computers 212-1, handheld units 212-h, mobile phones with Internet access or personal digital assistants (PDA) type computing devices. The PCs 212 are respectively connected to a corresponding SAU 214 through a suitable wired connection, such as an Ethernet type connection.

A SAU 214 permits its related PC 212 to connect to the network file server 230 through the BSP 220, the Internet gateway (IG) 222, and the network 224. In the reverse connection direction, that is, in terms of the data flow from the PC 212 to the server 230, the PC 212 provides an Internet Protocol (IP) level packet to the SAU 214. Then the SAU 214 encapsulates the wired framing (that is, the Ethernet framing) with appropriate wireless connection framing and encoding operations. The appropriately formatted wireless data packet is then transmitted via antennas 216 and 218 on one of the radio channels including the reverse link 50. At the location of the central base station, the BSP 220 extracts the radio link into a frame, reformats the packet into an IP format, and sends it through the Internet gateway 222. The packet is then scheduled to pass through any number and/or any type of TCP/IP network, such as the Internet 224, to its final destination, such as the network file server 230.

Data can also be transmitted from the network file server 230 to the PCs 212 in the direction of a forward link 40. In this case, an Internet Protocol (IP) packet originating from the file server 230 reaches the BSP 220 through the Internet 224 through the Internet gateway 222. Then the appropriate wireless communication protocol framing and encoding operations are added to the IP packet. The packet is then transmitted via antennas 218 and 216 to the intended receiving SAU 214. The receiving SAU 214 decodes the wireless packet format, and transmits the packet to the expected PC 212, which performs IP layer processing.

A known PC 212 and file server 230 can therefore be regarded as the endpoints of a duplex connection at the IP level. Once a connection is established, a user of the PC 212 can then transmit data to and receive data from the file server 230.

From the point of view of the second user group 210, the reverse link 50 is actually composed of a number of different channels including an incoming channel 251, a plurality of traffic channels 252-1,...252-t, and a maintenance channel 253. Type of logical and/or physical radio channel composition. The reverse link access channel 251 is used by the SAUs 214 to send a message to the BSP 220 requesting permission to use the traffic channel. The assigned traffic channel 252 then carries the payload data from the SAU 214 to the BSP 220. It should be understood that a known IP layer connection may actually be assigned to more than one traffic channel 252. In addition, a maintenance channel 253 can carry information such as synchronization and power control messages to further support the transmission of information on the reverse link 50.

Similarly, the second user group 210 has a forward link 40 including a call channel 241, a plurality of traffic channels 242-1...242-t, and a maintenance channel 243. The call channel 241 is used by the BSP 220 to not only inform the SAU 214 of the previous connection traffic channel 252 that has been allocated to the SAU, but also inform the SAU 214 of the traffic channel 252 allocated in the reverse connection direction. In an alternative embodiment, the BSP 220 does not specify the allocated traffic channel 252 in the reverse link direction; for example, a slotted aloha technique can be used. Then use the traffic channels 242-1...242-t on the forward link 40 to carry the payload data information from the BSP 220 to the SAUs 214. In addition, the maintenance channel 243 carries synchronization and power control information from the base station processor 220 to the SAUs 214 on the forward link 40.

It should be understood that there are usually more traffic channels 242 other than the calling channel 241 or the maintenance channel 243. In the preferred embodiment, the logical forward connected channels 241, 242, and 243 and the logical backward connected channels 251, 252, and 253 are defined by assigning a pseudo-random noise (PN) channel code to each channel. The system 10 is therefore a commonly known code division multi-directional access (CDMA) system, in which multiple coded channels can use the same radio frequency (RF) channel. The logical or code channels can also be further divided or assigned among multiple effective SAUs 214.

The sequence of signal processing operations is usually carried out by encoding the corresponding reverse link 50 logical channels 251, 252, and 253. In the reverse link direction, the transmitter is SAUs One of 214, and the receiver is a base station processor (BSP) 220. The preferred embodiment of the present invention is implemented in a CDMA digital mobile phone system (such as a system operating in accordance with the IS-95B standard), and the old users also appear in the environment on the reverse link 50. In an IS-95B system, reverse-linked CDMA channel signals are identified by assigning non-orthogonal pseudo-random noise (PN) codes.

Now we turn our attention to Fig. 2, and the channel coding process of the first old user group 110 will be described in more detail below. This first user level includes, for example, digital CDMA mobile phone system users who encode signals according to the IS-95B standard as described above. Individual channels are therefore identified by modulating the input digitized sound signal with one of the pseudo-random noise (PN) codes of each channel. Specifically, the channel coding process obtains an input digital signal 302 representing the information to be transmitted. A quadrature modulator 304 provides in-phase (i) and quadrature (q) signal paths to a pair of multipliers 306-i and 306-q. A short pseudo-random noise (PN) code generator 305 provides a short (in this example, a 2¹⁵-1 or 32767 bits) length code. The short code is therefore generally the same code used for each of the logical channels of the first group 110.

A second code modulation step is applied to the two signal paths by multiplying the (i) and (q) signal paths by an additional long PN code. This is done by the long code generator 307 and the long code multipliers 308-i and 308-q. The long code is used to uniquely identify each user on the reverse link 50. The long code can be a very long code, for example, only every 2⁴²-1 bit is repeated. The long code is applied at the short chip rate. For example, one bit of the long code is applied to each bit output by the short code modulation program, so that no further spreading effect occurs.

Individual users are identified by applying different phase shifts of the PN long code to each user.

It should be understood that it is not necessary to perform other synchronization steps for the first user group 110. In particular, these transmissions on the reverse link 50 are designed to be asynchronous and therefore not necessarily perfectly orthogonal.

FIG. 3 is a more detailed diagram of the channel coding process of the second user group 210. The second group 210 includes, for example, wireless data users who encode signals according to a format optimized for data transmission.

Individual channels are identified by modulating the input data with a code sequence that is the same as the pseudo-random noise (PN) code sequence used for the first user group 110. But as we will immediately understand, the channels in the second group 210 are uniquely identified by special orthogonal codes such as Walsh codes. Specifically, the channel coding process of the second user group 210 obtains an input digital signal 402 and applies it to multiple codes generated by a short code generator 405, a Walsh code generator 413, and a long code generator 407.

As a first step, a quadrature modulator 404 provides in-phase (i) and quadrature (q) signal paths to the first pair of multipliers 406-i and 406-q. The short pseudorandom noise (PN) code generator 405 provides a short (215 in this example) length code for spread spectrum purposes. This short code is therefore the same as the short PN code used for each channel of the first group 10.

One of the second steps of the procedure is to apply an orthogonal code, such as the code generated by the Walsh code generator 413. This is achieved by pushing the orthogonal code onto each of the in-phase signal path and the orthogonal signal path by multipliers 412-i and 412q. The orthogonal codes assigned to each logical channel are different and uniquely identify these channels.

In one final step of the procedure, a second pseudorandom noise (PN) long code is applied to the (i) and (q) signal paths. The long code generator 407 thereby transmits the long code to the corresponding one of the in-phase multiplier 408-i and the quadrature multiplier 408-q. This long code does not uniquely identify each user in the second group 210. Specifically, this code may be the same long code used in the first group to uniquely identify the first user group 110. Therefore, for example, it is applied in the same manner as a short chip rate code, so that one bit of the long code is applied to each bit output by the short code modulation procedure. In this way, all users in the second group 210 are like a single old user in the first group 110. However, the first The users of the second group 210 can be uniquely identified because they have been assigned a unique orthogonal Walsh code.

Since the execution in the preferred embodiment is performed on a reverse link 50, additional information must be fed back in order to maintain the orthogonality between the users in the second group 210. Specifically, a maintenance channel 243 is thus included in the forward link 40. A maintenance channel or "heartbeat" channel 253 also exists on the reverse link 50 and provides synchronization information and/or other timing signals so that the remote unit 214 can properly synchronize its transmission. The maintenance channel may be time slotted. For more details on the formatting of this backlink maintenance channel 253, please refer to the co-pending U.S. Patent Application No. 09/775,305 filed on February 1, 2001, titled "MAINTENANCE LINK USING ACTIVE/STANBY REQUEST CHANNELS" The full content of the case is incorporated into this article by reference.

It should be understood that certain infrastructure may therefore be shared by the second user group 210 and the first user group 110. For example, although the antennas 218 and 118 are shown as independent base station antennas in Figure 1, they may be a common antenna in due course. Likewise, the locations of the antennas can therefore be the same. This permits the second user group 210 to share equipment and physical expansion premises that are already being located and used by the old user 110. This greatly simplifies the deployment of wireless infrastructure for this new user group 210, for example, there is no need to build new sites and new antenna outlets.

BTS 120, BSP 220, BSC 123 or other network devices communicating with BTS 120 and BSP 220 can coordinate the phase shift of the long code available for BSP 220. The phase offset available for use by a non-old user comes from a set that is allocated to and/or allocated by the BTS 120, but it is not used by a BTS old user 110.

BTS 120 and BSP 220 can (i) communicate directly with each other via a communication link (not shown in the figure), (ii) respond to input from BSC 123, or (iii) communicate with each other via networks 124 and 224. Coordinate (ie synchronize) the timing of the forward connection of the BTS 120 and the BSP 220. Synchronized work helps time alignment Reverse link 50 and ensure proper transfer of old and non-old users 110, 210 when they move from BTS 120 to BSP 220 (and vice versa).

In addition, the power control of the reverse link signals from the old users 113 and SAUs 214 can be controlled by various techniques. For example, the BTS 120 and the BSP 220 can issue power commands or messages to the users 110 and 210. SAUs 214 and subscriber unit 113 can, for example, (i) increase the power of the corresponding reverse link signal by a smaller amount when BTS 120 and BSP 220 indicate that the power should be increased, and (ii) indicate both BTS 120 and BSP 220 To reduce the power, reduce the power of the reverse link signal by a larger amount (that is, more negative values). If one indicates that the power is to be increased and one indicates that the power is to be reduced, the affected SAU 214 reduces its power in this example. Alternative power control techniques for reverse connection signals can also be used.

FIG. 4 is a simplified diagram of a multi-path (ie, "multi-path") environment 400, in which one of the users in the second group is communicating with the base transceiver station 120. In this example, the user utilizes a subscriber access unit (SAU) 214-1 deployed in a car 401 to communicate with the BSP 220 via the antenna tower 118 in a reverse connection. In this figure, since it is transmitted in a multi-path environment 400, the reverse link signal uses multiple paths 405, 405' (collectively referred to as 405) between the SAU 214-1 and the BSP 220. In this example, the multipath environment 400 is caused by a man-made structure 402 (ie, a building) with electromagnetic properties reflecting RF transmission. The multipath 405 is referred to as a reverse connection primary path 405 and a reverse connection secondary path 405'. Because there are two or more paths, there will be the same number of reverses with a common long orthogonal code and a unique orthogonal code such as a Walsh code (or other suitable orthogonal codes as described in Figure 3) The connection signals 410, 410' (collectively referred to as 410) are received at the BSP 220.

Since the two reverse connection signals 410 and 410' are received at the BPS 220 as having the same unique orthogonal code, the BSP 220 has a chance to perform the diversity selection of the reverse connection signals 410 and 410'. The BSP 220 can select, for example, the reverse link signals 410, 410' with the highest signal-to-noise ratio (SNR) to maximize the subscriber unit 214-1 and the BSP 220 Performance of reverse link communication between. Other metrics can be used to select the "best" reverse link signal from the subscriber unit 214-1.

After selecting the "best" reverse link signal, the BSP 220 uses the selected reverse link signal 410 to deviate from the selected reverse link signal 410 in the second group 210 to be orthogonally calibrated to other subscriber units 214-2, ..., the timing offset of the reverse connection signal of 214-h (Figure 1) is determined based on the total timing offset of the selected reverse connection signal 410. The BSP 220 transmits the total timing offset to the SAU 214-1 in the forward link 415 to align the selected reverse link signal 410 with the reverse link signals from other subscriber units 214-2,...,214-h. The fine timing offset is also transmitted in the forward link 415. The total and minute timing offset feedback can be transmitted to the user unit 214-1 in the form of a timing command or timing report.

In the case of a timing report, the subscriber unit 214-1 autonomously shifts the long code (that is, the orthogonal code of the long code commonly used by other subscriber units in the group) so as to be orthogonal to the long code of other subscriber units Ground calibration, thereby making the second user group 210 look like a single user to the first user group 110.

The BSP 220 can also determine a power level of the selected reverse link signal and provide feedback of the power level to the user unit 214-1 in the form of a command or report. The BSP 220 can determine whether the SNR of the selected reverse link signal meets a quality criterion. The quality criterion may include at least one of the following: (a) the metric of the secondary path (or alternative or candidate) exceeds a threshold of a predetermined time interval, (b) the metric of the secondary path exceeds a predetermined time interval A threshold relative to the primary path, (c) the metric of the primary path falls below an absolute metric, and (d) the metric of the secondary path exceeds an absolute metric. The metrics can include at least one of the following: (a) power, (b) SNR, (c) power variable, (d) SNR variable, (e) power, SNR, or relative ratio of the two paths , (F) bit error rate, and (g) energy per chip divided by interference density (Ec/Io). When a receiver of the base receiving station receives a reverse link signal that is in a phase that is different from the reverse link signal of other field units in the same group and is calibrated orthogonally When the signal (that is, the current path) reversely connects signals with different phases, it represents an alternative path.

The power level feedback may cause the user unit 214-1 to adjust the power level of the encoded signal in response to the feedback. For example, when (i) the SNR of the selected path does not meet the quality criterion or (ii) the SNR of a non-selected path meets a quality criterion, the BTS 120 can shift the timing of the reverse link signal through the use of summation and fine timing offset. Bit, causing the phase shift of the long code in the subscriber unit. The phase shift of the long code causes the "best" reverse link signal to be time aligned with the reverse link signal from other subscriber units using the same long code.

Figure 5 is a block diagram of the BSP 220 and an example of the processing units 505-520 that can be used by the BTS 120 to determine a total timing offset 417. The processing units include a receiver 505, a correlator 510, a selector 515, and a quadrature timing controller 520.

In operation in the multipath environment 400, the BSP 220 receives the multipath reverse link signals 410, 410' from the antenna tower 118 at the receiver 505. The receiver 505 receives the multi-path reverse link signals 410, 410', which include the same common code and unique orthogonal code, and travel from the subscriber unit 214-1 to the BSP 220 on the main path 405 and at least the primary path 405' .

The receiver 505 outputs the same number of reverse connection signals (that is, equivalent to the number of reverse connection paths 405, 405' in the multipath environment 400), and each signal includes a common long code and a unique orthogonal code. After being processed by the receiver 505, each received reverse link signal 410, 410' is sent to the correlator 510 and the quadrature timing controller 520 in the form of baseband signals 412, 412'. The correlator 510 associates a metric with the data of each received reverse link signal 410, 410'. The correlator 510 sends the metric and the reverse connection signal data to the selector 515 for selecting the reverse connection signal 410, 410' related to the best metric. In other words, the reverse link signal 410, 410' that provides the best signal for reverse link communication is selected as the opposite of the other user units 214-2,...,214-h from the second group 210 Calibrate orthogonally to the link signal.

The selector 515 sends the information 517 corresponding to the selected reverse connection signal to the quadrature timing controller 520. Based on the information 517, the quadrature timing controller 520 processes the corresponding (ie, the "best") reverse link signal and determines the total and minute timing offsets 417 and 418. The controller 520 determines the offset 417, 418 based on the timing of the selected reverse link signal relative to the timing of the reverse link signal from other user units 214-2,...,214-h using the same long code, as described above Refer to Figure 3 as described.

Continuing to refer to Figure 5, the total and minute timing offsets 417, 418 are sent to a transmitter (Tx) 525. The transmitter 525 transmits the total and minute timing offsets 417, 418 to the user access unit 214-1 on the forward link 415, as described above with reference to FIG. 4. It should be understood that the quadrature timing controller 520 can issue the total and minute timing offsets 417, 418 for sending to the subscriber unit 214-1 in the following manner: first, the total timing offset 417 is sent, and then the reverse connection signal has been After being sufficiently shifted to approximate the quadrature calibration with the reverse connection signals from other user units 214-2,..., 214-h, the quadrature timing controller 520 determines the slight timing offset 418.

Figure 6 is a timing diagram 605, which depicts the timing of multiple reverse link signals 410, 410' received from five field units AE in a multi-path environment 400. Timing diagram 605 includes a set of signals represented by vertical check marks for five field units AE (such as 214-1, 214-2, 214-3, 113-1, and 214-h) operating in a multipath environment The field units AC and E are non-legacy wireless devices, which can cause a total phase shift of one of the common codes for transmission in the reverse link and can include a unique orthogonal code in the transmitted reverse link signal to distinguish these reverse links. Reverse connection signal of other non-old subscriber units. The field unit D is an old wireless device that does not support a unique orthogonal code in the reverse link signal nor the total phase shift of the common code.

When the reverse connection signals of the non-old field units AC and E are in quadrature calibration And thus behave like a single field unit but distinguished by a unique orthogonal code, the timing of each reverse connection is calibrated at a common calibration time 610. However, in a case where a known field unit is used for multipathing, when multiple reverse link signals sent by the known field unit are received at the base station 120 and used with the same unique orthogonal code (ie, as With reference to the Walsh code identification described in FIG. 1, the base station 120 can select one of a plurality of reverse link signals for calibration at the common calibration time 610.

For example, continuing to refer to Figure 6, the field unit A received the same reverse connection signal by the BSP 220 at the two time points shown by the check marks 615 and 615'. In this embodiment, for the received field unit A reverse connection signal represented by a check mark, the correlator 510 (FIG. 5) determines an offset time and signal metric. Based on the signal metric, the selector 515 determines which of the two reverse connection signals 615, 615' is to be the reverse of the other field units (field units B, C, and E) in the same group at the common orthogonal calibration time 610 Link signal calibration. In the case of field unit A in this example, the reverse link signal 615 closer to the common quadrature calibration time 610 is selected based on the signal metric for use by the BSP 220. Therefore, the BSP 220 issues a total timing offset 417 corresponding to the offset time to bring the selected reverse link signal 615 to the quadrature calibration state at the common quadrature calibration time 610. Field unit A shifts the phase of the common long code to align with the reverse connection signals of field units B, C, and E. Naturally, other received reverse link signals 615' from field unit A are shifted by the same amount due to the long orthogonal code phase shift.

The field unit B is in the calibration state at the orthogonal calibration time 610, and as determined by a single check mark along its timeline, it is not in a multi-path environment. Therefore, the BSP 220 does not necessarily have to make a decision about whether an uncalibrated received reverse link signal has a higher metric, and the BSP 220 does not necessarily feedback a timing offset to the field unit B.

Field unit C is another field unit in a multi-path environment 400. In the case of field unit C, the selector 515 at the BSP 220 determines that it is The received reverse connection signal 625 with the reverse connection of the field unit in the calibrated state has an expected metric smaller than that of the uncalibrated reverse connection signal 625'. It should be understood that the uncalibrated reverse link signal 625' may be a reverse link signal traveling within the primary path or the secondary path. In either case, the BSP 220 issues a total timing offset 417 used to shift the long code to calibrate the second reverse link signal 625' at the common quadrature calibration time 610. The other received concatenated signals 625 are thus shifted out of the quadrature calibration state.

Field unit D is an old field unit, and its reverse connection signal is not brought to the non-legacy field unit AC and E for calibration. When the reverse link from the field unit D is brought to the reverse link calibration with other field units, it may cause destructive interference, because the field unit D does not contain unique orthogonal codes like the non-old field units AC and E. Since it is an old field unit, it should have its own unique long code phase offset that is (in terms of time) far away from non-old field units AC and E.

In the case of the field unit E, its reverse connection signal is calibrated within the common calibration time 610 and is not affected by a multipath environment; therefore, there is no timing adjustment for this reverse connection signal.

Figure 7 is a flowchart of the procedures 700 and 765 executed by the BSP 220 and the user access unit (SAU) 214-1, respectively, according to the above description. In this embodiment, the SAU 214-1 procedure 765 starts (step 745) and transmits a reverse link signal with a common long code and a unique orthogonal code to the BSP 220 (step 750). In a multi-path environment 400, a primary path 405 and a secondary path 405' that may be caused by natural or man-made structures are paths along which the reverse connection signals 410, 410' travel to the BSP 220.

The BSP procedure 700 starts (step 705) and receives reverse connection signals 410, 410' (step 710). The BSP procedure 700 associates a metric with each received reverse link signal 410, 410' (step 715). Based on these metrics, the BSP program 700 selects a "best" reverse connection signal from the reverse connection signals received from the SAU 214-1 in each primary and secondary path 405, 405' (step 720).

The BSP program 700 determines whether the selected reverse link signal is orthogonally calibrated with reverse link signals from other subscriber units using the common long code (see FIG. 6) (step 725). If the best reverse link signal 720 from SAU 214-1 is orthogonally calibrated, the BSP procedure 700 ends (step 740) without sending back timing adjustment information to SAU 214-1, or in an alternative embodiment Zero phase shift. If the best reverse link signal is not orthogonally calibrated with the reverse link signals of other subscriber units using the common long code, the BSP program 700 determines a total timing offset (step 730) and offsets the total timing Transfer to SAU 214-1 (step 735).

The procedure 765 of the SAU 214-1 receiving the total timing offset 417 causes the SAU 214-1 to make a coarse phase adjustment of one of the common long codes in the reverse link signal (step 755). The SAU procedure 765 ends (step 760) or can continue to receive the total or minute timing offset (not shown) from the BTS 120 as described above with reference to FIG. 5.

It should be understood that the procedures described in this specification can be implemented in hardware, firmware, or software. In the case of being implemented in software, the software may be stored on a computer-readable medium, such as RAM, ROM, CD-ROM, floppy disk or optical disc, or other computer-readable medium. The software is loaded from memory and executed by a processor, such as a general-purpose or special-purpose processor, which is in the BSP 220 and operates in the BTS 120 as needed. Similarly, a program executed in the software of a user unit is stored on a computer readable medium and executed by a processor operating in it.

It should also be understood that a single user in the second group 210 can use more than one unique orthogonal (Walsh) code. For example, the user may have a large amount of payload to be sent to the BSP 220, so the user may use two channels, and each channel is identified as the user based on a unique orthogonal code. Moreover, in other embodiments or network environments, the long code may be a short code, an orthogonal code, or other codes that can be used for the same purpose as the above long code.

In addition, it should also be understood that the present invention is applicable to other wireless networks. For example, in an 802.11 wireless local area network (WLAN) network, an access point (AP) performs processing operations similar to the base transceiver station described in this manual, and a user station performs the same processing operations as described in this manual The on-site unit/user access unit handles similar operations.

Although the preferred embodiment of the present invention has been described with figures and texts, those skilled in the art will understand that various changes in form and details can be made without departing from the scope of the present invention defined by the scope of the appended patent application.

<p>AEField Unit</p><p>BSCBase Station Controller</p><p>BSPBase station processor</p><p>BTSBase Transceiver Station</p><p>IInternet</p><p>IGInternet Gateway</p><p>PNPseudo-random noise</p><p>PSTNPublic Switched Telephone Network</p><p>RFRadio Frequency</p><p>SAURemote User Access Unit</p><p>TxTransmitter</p><p>Walsh CodeSpecial Orthogonal Code</p><p>10Divided code multi-directional access (CDMA) communication system block diagram</p><p>40forward link</p><p>50Reverse link</p><p>110First User Group</p><p>113User Unit</p><p>113-1, 113-2Wireless mobile phone</p><p>113-hCellular mobile phone</p><p>118,218Base station antenna</p><p>120BTS</p><p>123BSC</p><p>124PSTN</p><p>141, 241Call channel</p><p>142, 152Traffic channel</p><p>144, 154Other logical channels</p><p>151Access Channel</p><p>210Second User Group</p><p>212-1, 212-2, ... 212-hRemote personal computer device</p><p>214-1, 214-2, ...214-hSAUs</p><p>216-1, 216-2,...216-hRelated antenna</p><p>220BSP</p><p>222IG</p><p>224I</p><p>230Network File Server</p><p>242-1...242-t,252-1...252-tFlow channel</p><p>243, 253Maintenance channel</p><p>251Access Channel</p><p>302Input digital signal</p><p>304,404Quadrature Modulator</p><p>305, 405Short PN code generator</p><p>306-i and 306-q, 406-i and 406-qMultiplier</p><p>307, 407Long PN code generator</p><p>308-i, 308-qLong PN code multiplier</p><p>400Multipath ("Multipath") environment diagram</p><p>401Car</p><p>402Input digital signal/man-made structure</p><p>405, 405' (collectively referred to as 405)Multiple paths (reverse link primary/secondary paths)</p><p>408-iIn-phase multiplier</p><p>408-qOrthogonal Multiplier</p><p>410, 410' (collectively 410)Reverse link signal</p><p>412, 412' baseband signal</p><p>412-i and 412qMultiplier</p><p>413Walsh Code Generator</p><p>415forward link</p><p>417Total timing offset</p><p>418Slight timing offset</p><p>505Receiver</p><p>510Correlator</p><p>515Selector</p><p>517Selected reverse link signal information</p><p>520Orthogonal timing controller</p><p>525Tx</p><p>605Multiple received from five field units AE in the multipath environment 400 Timing diagram of reverse connection signals 410, 410'</p><p>610Common orthogonal calibration time</p><p>615, 615'Two reverse connection signals</p><p>625Reverse link signal received during calibration</p><p>625'Uncalibrated reverse link signal</p><p>700 and 765Program flow chart executed by BSP 220 and User Access Unit (SAU) 214-1, respectively</p>

Figure 1 is a block diagram of a wireless communication system that supports orthogonal and non-orthogonal reverse connections.

Figure 2 is a block diagram of a circuit used by the access terminal of Figure 1.

Figure 3 is a block diagram of the circuit of Figure 2, which further includes a code generator for operation with other access terminals on an orthogonal reverse connection.

Figure 4 is a block diagram of an environment in which a base station in Figure 1 controls the timing of orthogonal reverse link signals under the condition of multiple channels.

Figure 5 is a block diagram of the base transceiver station (BTS) of Figure 1.

Figure 6 is a timing diagram of the reverse link signal received by the base transceiver station in Figure 4.

Figure 7 is a flowchart of a program that can be executed by the base receiving station and the access terminal of Figure 4.