Resource allocation for shared signaling channels

Claiming priority under 35 USC 120

This application claims the priority of US Application No. 11 / 261,158, entitled "SHARED SIGNALING CHANNEL", filed October 27, 2005. This US application is thereby explicitly incorporated herein by reference.

The present disclosure relates to the field of wireless communication, and particularly to resource allocation for shared signaling channels in wireless communication systems.

The wireless communication system can be configured like a multiple access communication system. In such a multiple access system, the system simultaneously supports multiple users across a predefined set of resources. The communication device establishes a link in the communication system by requesting access and receiving permission.

The resources that the system grants to the device requesting communication largely depend on the type of multiple access system being implemented. For example, some multiple access systems can allocate resources based on time, frequency, code space, or a combination of factors.

The wireless communication system communicates the allocated resources and also ensures that no overlapping resources are allocated to two or more communication devices so that the quality of the communication link to that communication device does not deteriorate. Need to track them. In addition, the wireless communication system needs to track the allocated resources in order to track the resources released or available at the end of the communication link.

Wireless communication systems typically allocate resources centrally to communication devices and their corresponding communication links, for example from a central communication device. Allotted resources, and in some cases de-allocated resources, need to be communicated to the communication device. Typically, wireless communication systems provide one or more communication channels for allocating resources and transmitting the overhead associated with them.

However, the amount of resources allocated to the overhead channel typically impairs the resources and the corresponding communication capacity of the wireless communication system. Resource allocation is an important element of communication systems, and care must be taken to ensure that the channels allocated for resource allocation are robust. On the other hand, wireless communication systems require a balance between the need for robust resource allocation channels and the need to minimize adverse effects on communication channels.

Therefore, there is a need for a resource allocation channel that provides robust communication and minimizes system performance degradation.

Overview

Shared signaling channels are used in wireless communication systems to provide signaling messages to access terminals in the system. Shared signaling channels are assigned to a predetermined number of subcarriers within an arbitrary frame. A predetermined number of subcarrier allocations for a shared signaling channel establishes a fixed bandwidth overhead for that channel. The actual subcarriers assigned to the channel change cyclically and according to a predetermined frequency hopping schedule. The amount of signal power allocated to the signaling channel varies on a symbol-by-symbol basis, depending on the power requirements of the communication link. A shared signaling channel can direct each message carried on that channel to one or more access terminals. Unicast messages or other otherwise addressed messages allow channel power to be controlled on a per-request for individual communication links.

The disclosure includes a method of generating control channel messages in a wireless communication system. The method comprises allocating logical control channel resources to physical channel resources. Here, the logical control channel resource is distinct from the logical traffic channel resource allocated for data transmission, and is also different from the physical channel resource corresponding to the combination of the subcarrier and the OFDM symbol.

The disclosure also includes a device for generating signaling channel messages, which device comprises a scheduler for allocating logical control channel resources to physical channel resources. Here, the logical control channel resource is distinct from the logical traffic channel resource allocated for data transmission, and is also different from the physical channel resource corresponding to the combination of the subcarrier and the OFDM symbol. The device also sends to send at least one signaling message using a signaling module to generate at least one signaling message and at least some subcarriers and OFDM symbols assigned to the logical signaling channel. Including the machine.

The features, objectives, and effects of the disclosed embodiments will be more apparent from the detailed description below, along with the figures with the same reference numbers attached to the same elements.

Detailed explanation

In an OFDM wireless communication system, a shared signaling channel (SSCH) is used to communicate various signaling messages and feedback messages executed in the system. This wireless communication system runs SSCH as one of several forward communication channels. SSCH is shared among multiple access terminals within the communication system at the same time.

The wireless communication system communicates various signaling messages on the forward link SSCH. For example, a wireless communication system includes a permission message, a forward link assignment message, and a reverse link assignment message, as well as other signaling messages communicated on a forward channel.

SSCH is also used to communicate feedback messages to the access terminal. The feedback message includes an acknowledgment message confirming that the access terminal transmission was successfully received. The feedback message also includes a reverse link power control message used to instruct the communicating access terminal to change the communication power.

The channels actually used in one SSCH are all or some of the above. In addition, other channels may be included in the SSCH in addition to or in place of the channels.

The wireless communication system allocates a predetermined number of subcarriers, OFDM symbols, or a combination thereof to the SSCH. The allocation of a predetermined number of subcarriers, OFDM symbols or combinations thereof to the SSCH establishes a bandwidth overhead for that channel. The actual subcarriers, OFDM symbols or combinations thereof assigned to SSCH change cyclically and according to a predetermined frequency hopping schedule. In some embodiments, the subcarriers, OFDM symbols or combinations thereof assigned to the SSCH vary throughout each frame.

The amount of power allocated to an SSCH varies depending on the requirements of the communication link carrying that SSCH. For example, SSCH power is increased when SSCH messages are sent to distant access terminals. Conversely, SSCH power is reduced when SSCH messages are sent to nearby access terminals. If there are no SSCH messages to be transmitted, the SSCH does not require power allocation. When a unicast message is executed, the power allocated to the SSCH can vary from user to user, so the SSCH requires a relatively low power overhead. The power allocated to the SSCH increases only when required by a special communication link.

The degree of interference that SSCH exerts on data channels for various access terminals varies based on the relative power levels of the SSCH and data channels, as well as the subcarriers assigned to the SSCH and access terminals. SSCH is virtually non-interfering to many communication links.

FIG. 1 is a simplified functional block diagram of a wireless communication system 100 in which SSCH is performed on a forward link. System 100 includes one or more fixed elements capable of communicating with one or more access terminals 110a-110b. System 100 in FIG. 1 is a general depiction of a wireless telephone system or wireless data communication system, but the system 100 is not limited to wireless telephone systems or wireless data communication systems, and the system is shown in FIG. It is not limited to having the specific element shown in 1.

The access terminal 110a typically communicates with one or more base stations 120a or 120b, which are depicted here as fan-shaped cellular towers. Another aspect of system 100 includes an access point instead of base station 120a or 120b. In such a system 100, BSC130 and MSC140 can be omitted and replaced with one or more switches, hubs or routers.

As used herein, a base station may be a fixed station used to communicate with a terminal, and an access point, node so called or having some or all of its functionality. It may be B, or any other technical term. An access terminal may also be a user equipment (UE), wireless communication device, terminal, mobile station, or other term that is so called or has some or all of its functionality. Good.

The access terminal 110a typically communicates with a base station, eg, the base station 120b, which provides the strongest received signal strength within the access terminal 110a. The second access terminal 110b also communicates with the same base station 120b. However, the second access terminal 110b is located at the edge of the area covered by the base station 120b, away from the base station 120b.

One or more base stations 120a-120b schedule channel resources used by forward links, reverse links, or both. Each of the base stations 120a-120b uses SSCH to communicate subcarrier assignments, acknowledgment messages, reverse link power control messages, and other overhead messages.

Each of the base stations 120a-120b is a base station controller (BSC).<u style="single">130</u>The signal path to the appropriate base station 120a-120b and the signal path from the appropriate base station 120a-120b are defined. BSC<u style="single">130</u>Is a Mobile Switching Center (MSC) that acts as an interface between access terminals 110a-110b and the Public Switched Telephone Network (PSTN) 150.<u style="single">140</u>Combined with. In other embodiments, the system 100 may implement a Packet Data Serving Node (PDSN) in place of or in addition to the PSTN150. The PDSN acts as an interface between a packet switched network, such as network 160, and the wireless portion of system 100. In some embodiments, the system<u style="single">100</u>Does not need to use PSTN150 and can connect MSC140 directly to network 160. In other embodiments, both MSC140 and PSTN150 can be omitted and the BSC 130 and / or base station 120 can be coupled directly to the packet-based network or circuit switch network 160.

MSC<u style="single">140</u>Also acts as an interface between access terminals 110a-110b and network 160. Network 160 is, for example, a local area network (LAN) or a wide area network (WAN). In some embodiments, network 160 includes the Internet and therefore MSCs.<u style="single">140</u>Is combined with PSTN150 and network 160. MSC<u style="single">140</u>Can also coordinate inter-system handoffs with other communication systems (not shown).

The wireless communication system 100 is configured as an OFDMA system that communicates with bidirectional links in the forward and reverse directions using OFDM communication. The term forward link refers to a communication link from base station 120a-120b to access terminals 110a-110b, and the term reverse link refers to a communication link from access terminal 110a-110b to base stations 120a-120b. Both base stations 120a-120b and access terminals 110a-110b can allocate resources for channel and interference estimation.

Base stations 120a, 120b and access terminal 110 broadcast pilot signals for channel and interference estimation purposes. Pilot signals include wideband pilots, collections of narrowband pilots that span the entire spectrum, or a combination thereof.

The wireless communication system 100 includes a set of subcarriers, or in other words, tones that increase the operating bandwidth of the OFDMA system. Typically, the subcarriers are equally spaced. The wireless communication system 100 allocates one or more subcarriers as a guard band, and the system 100 does not use the subcarriers in the guard band for communication with the access terminals 110a-110b.

In some embodiments, the wireless communication system 100 includes 2048 subcarriers with an extended operating frequency band of 20 MHz, each of which is divided into independent carriers, each carrier having its own SSCH and other resources at a fixed portion of 20 MHz. It is housing with. A guard band having substantially the same bandwidth as the bandwidth occupied by one or more subcarriers is assigned to each end of the operating band.

The wireless communication system 100 can perform frequency division duplex (FDD) on forward and reverse links. In the FDD aspect, the forward link is a frequency offset from the reverse link. Therefore, the forward link subcarrier is a frequency offset from the reverse link subcarrier. Typically, the frequency offset is fixed and the forward link channel is separated from the reverse link subcarrier by a predetermined frequency offset. Forward and reverse links use FDD to communicate simultaneously.

In another aspect, the wireless communication system 100 can perform Time Division Duplex (TDD) of forward and reverse links. In this embodiment, the forward link and the reverse link share the same subcarrier, and the wireless communication system 100 alternately communicates between the forward link and the reverse link at predetermined time intervals. In TDD, the allocated frequency channels are the same for forward and reverse links, but the time allocated for forward and reverse links is different. Channel estimation performed on forward or reverse link channels is generally accurate because both complementary channels are interrelated.

The wireless communication system 100 can also implement an interlacing format in one or both of the forward and reverse links. Interlacing is a form of time division multiplexing in which communication link timing is periodically assigned to one of a predetermined number of interlace periods. A particular communication link to one of the access terminals, eg 110a, is assigned to one of the interlaced periods, and communication on this particular communication link occurs only during the allotted interlaced period. For example, wireless communication system 100 can run in six interlaced periods. Each interlaced period identified in 1-6 has a predetermined duration. Each interlace period occurs periodically over 6 periods. Therefore, communication links assigned during a particular interlaced period become active once every six periods.

Interlaced communications are particularly useful in wireless communication systems 100 that implement automatic repeat request schemes such as the Hybrid Automatic Repeat Request (HARQ) algorithm. The wireless communication system 100 can implement the HARD method for processing data transmission. In such a system, the transmitter makes the initial transmission at the first data rate and automatically resends the data if it does not receive an acknowledgment message. The transmitter can perform later retransmissions at a lower data rate. HARQ incremental redundancy retransmission schemes can improve system performance in terms of providing early termination gain and resilience.

The interlacing scheme allows sufficient time for processing the ACK message before the next allocated interlacing period occurs. For example, the access terminal 110a can receive the transmitted data and send an ACK message, and the base station 120b receives the ACK message, processes it in time, and resends it during the next interlaced period. Can be prevented. Alternatively, if base station 120b fails to receive the ACK message, base station 120b can resend data during the next interlace period assigned to access terminal 11a.

Base stations 120a-120b send SSCH messages at each interlace, but the messages that occur at each interlace can be limited to the messages for access terminals 110a-110b assigned to that particular active interlace. Base stations 120a-120b can limit the amount of SSCH messages that need to be scheduled during each interlace period.

The radio communication system 100 can perform Frequency Division Multiplex (FDM) SSCH on the forward link for signaling and feedback message communication. Each base station 120a-120b assigns a predetermined or variable subcarrier, OFDM symbol or a combination thereof to the SSCH. In other aspects, logical resources (logical) Only resources) are allocated to the SSCH, and those resources are mapped according to a mapping scheme that is the same as or different from the mapping scheme for traffic channels. The wireless communication system 100 allocates fixed or variable bandwidth overhead to the SSCH. Each base station 120a-120b allocates a predetermined percentage of physical channel resources, such as subcarriers, OFDM symbols, or a combination thereof, to the SSCH, which has a minimum and a maximum. In addition, each base station 120a or 120b allocates a different physical channel resource to the SSCH. For example, each base station 120a or 120b allocates about 10% of physical channel resources to the SSCH.

Each base station, eg 120b, can allocate logical resources to the SSCH in the form of multiple nodes based on the channel tree. The channel tree is a channel model with multiple branches ending in leaves or base nodes. Each node in the tree is labeled, and each node identifies all nodes and the base nodes below them. The leaves of the tree, or base nodes, correspond to the smallest allottable logical resources, such as a single subcarrier, a single OFDM symbol, or a combination thereof. In this way, the channel tree provides a logical map for the allocation and tracking of available physical channel resources in the wireless communication system 100.

Base station 120b can map nodes to physical channel resources used in forward and reverse links based on the channel tree. For example, base station 120b allocates a predetermined number of resources to the SSCH, which is done by assigning the corresponding number of base nodes to the SSCH from the channel tree. Base station 120b maps the logical node allocation to the physical channel resource allocation that is ultimately transmitted by base station 120b.

Using a logical channel tree or other logical structure is advantageous for tracking the resources allocated to the SSCH when the physical channel resource allocation is changed. For example, base stations 120a-120b can perform frequency hopping algorithms on SSCH as well as other channels such as data channels. Base stations 120a-120b implement a pseudo-random frequency hopping method for each of the assigned subcarriers. Base stations 120a-120b use a frequency hopping algorithm to map a logical node from the channel tree to the corresponding physical channel resource allocation.

Frequency hopping algorithms can perform frequency hopping on a symbol basis or block basis. Symbol rate frequency hopping frequency hops individual subcarriers that are different from the other subcarriers, unless two nodes are assigned to the same physical subcarrier. In block hopping, adjacent blocks (a contiguous blocks) of multiple subcarriers are frequency-hopped while maintaining the adjacent block structure. From the standpoint of the channel tree, branch nodes higher than the leaves are assigned to the hopping algorithm. The base node below the branch node follows the hopping algorithm applied to the branch node.

Base stations 120a-120b can perform frequency hopping on a periodic basis, such as frame by frame, by a fixed number of frames, or by a predetermined number of other OFDM symbols. As used herein, a frame refers to a predetermined OFDM symbol structure, which contains one or more preamble symbols and one or more data symbols. The receiver can use the same frequency hopping algorithm to determine which subcarriers have been assigned to SSCH or the corresponding data channel.

Base stations 120a-120b can modulate each of the subcarriers assigned to the SSCH using SSCH messages. The message includes a signaling message and a feedback message. Signaling messages include connection permission messages, forward link block allocation messages, and reverse link block allocation messages. Feedback messages include acknowledgment (ACK) messages and reverse link power control messages. The actual channels used in SSCH can be all or some of the above. Also, other channels may be included in the SSCH in addition to or in place of the channels described above.

The connection permission message is used by base station 120b to confirm an access attempt by access terminal 110a and assign a media access control identification (MACID). Also, the connection permission message can include an initial reverse link power control message. The sequence of modulation symbols corresponding to the connection authorization is scrambled according to the index of the previous access probe sent by the access terminal 110a. This scramble allows the access terminal 110a to respond only to the connection permission block corresponding to the probe sequence it has transmitted.

Base station 120b uses forward and reverse link access block messages to provide forward or reverse link subcarrier allocation. The assigned message can include other parameters such as modulation method, coding method, and packet method. Base stations typically provide channel assignments to specific access terminals and use the assigned MAC IDs to identify target recipients.

Base stations 120a-120b typically transmit an ACK message to a particular access terminal 110a-110b in response to a successful transmission reception. Each ACK message can be as simple as a 1-bit message displaying a positive or negative acknowledgment. The ACK message is linked to each subcarrier or to a specific MAC ID, for example using the relevant nodes in the channel tree for other subcarriers for that access terminal. In addition, the ACK message is encoded in multiple packets for diversity purposes.

Base stations 120a-120b can transmit reverse link power control messages to control the power density of reverse link transmissions from each access terminal 110a-110b. Base stations 120a-120b transmit a reverse power control message to instruct access terminals 110a-110b to increase or decrease their power density.

Base stations 120a-120b can individually unicast each SSCH message to a particular access terminal 110a-110b. In unicast messaging, each message is modulated and power controlled independently of the other messages. Alternatively, messages addressed to a particular user are combined and independently modulated and power controlled.

In another aspect, the base stations 120a-120b can combine messages for a plurality of access terminals 110a-110b and multicast the combined messages to a plurality of access terminals 110a-110b. In multicast, messages for multiple access terminals are grouped into a co-encoded, power-controlled set. Power control of co-encoded messages needs to target access terminals with the worst communication links. Therefore, if the messages for the two access terminals 110a and 110b are combined, the base station 120b controls the power of the combined messages to ensure that the access terminal 110a with the worst link receives the transmission. set. However, the power level required to ensure that the worst communication link is met is probably substantially higher than that required for access terminal 110b, which is closer to base station 120b. Therefore, in some embodiments, the SSCH message is co-encoded and power controlled for access terminals having substantially similar channel characteristics, such as SNR, power offset, and the like.

In another aspect, base stations 120a-120b group all message information for all access terminals 110a-110b served by one base station, eg 120b, and combine all of this combined message. It can be broadcast to access terminals 110a-110b. In the broadcast approach, all messages are jointly coded and modulated. Power control, on the other hand, targets access terminals with the worst forward link signal strength.

Unicast signaling is advantageous in situations where multicast or broadcast requires significant power overhead to reach the cell edge with a sufficient number of bits. Unicast messages are useful for power sharing between access terminals with different forward link signal strengths in power control. Also, unicast messaging is beneficial to the fact that many reverse link-based nodes cannot be assigned to a given point at once, so it does not require the energy consumed to report an ACK on those nodes. ..

From a MAC logic perspective, the unicast design allowed the radio communication system 100 to scramble ACK messages with the target MAC ID and was targeted by ACK (via allocation signaling errors such as missing deallocation). Prevents an access terminal that misunderstands that a related resource has been allocated, in fact misinterpreting an ACK intended for another MAC ID. Then, the access terminal recovers from the erroneous allocation state because the packet is not positively confirmed after a single packet and the access terminal terminates the erroneous allocation.

From the point of view of link performance, the main advantage of broadcast or multicast is the coding gain by joint encoding. However, the power control gain substantially exceeds the coding gain for the actual geometry distributions. Unicast messaging also offers a higher error rate than co-coded messages and CRC protected messages. However, in practice, a achievable error rate of 0.01% to 0.1% is sufficient.

For base stations 120a-120b, it is advantageous to multicast or broadcast some messages while unicasting other messages. For example, an assign message can automatically de-assign the resources in use corresponding to the subcarriers displayed in the assign message from the access terminal. Therefore, assignment messages are often multicast because they target not only the users identified in the assignment message, but also the recipients intended for the assignment.

FIG. 2 is a simplified functional block diagram of an aspect of the OFDM transmitter 200 that is incorporated into the base station of the wireless communication system of FIG. Transmitter 200 transmits one or more OFDM signals to one or more access terminals. The transmitter 200 includes an SSCH module 230 for generating and implementing SSCHs in a forward link.

Transmitter 200 includes a data buffer 210 for accumulating scheduled data for one or more access terminals. The data buffer 210 holds scheduled data for each of the access terminals located in the coverage area supported by the corresponding base station, for example.

The data is, for example, unencoded raw data or encoded data. Typically, the data stored in the data buffer 210 is unencoded, coupled to the encoder 212 and encoded by the encoder 212 according to the desired encoding rate. The encoder 212 can include coding for error detection and forward error correction (FEC). The data in the data buffer 210 is encoded according to one or more coding algorithms. Each coding algorithm and the resulting coding rate is related to the particular data format of the multi-system hybrid automatic repeat request (HARQ) system. Coding is convolutional coding, block coding, interleaving, direct sequence spreading, cyclic redundancy. Coding) and the like, or other coding, but not limited to these.

The encoded data to be transmitted is coupled to the series / parallel converter and the signal mapper 214, and the series data stream from the encoder 212 is converted into a plurality of parallel data streams. The signal mapper 214 determines the number and identity of subcarriers for each access terminal based on the inputs provided by the scheduler (not shown). The number of carriers assigned to each identified access terminal is a subset of all available carriers. Therefore, the signal mapper 214 maps the data scheduled for one particular access terminal to a parallel data stream that corresponds to the data carrier assigned to that access terminal.

The SSCH module 230 generates an SSCH message, encodes the message, and provides the encoded message to the signal mapper 214. The SSCH module 230 also provides the identity of the subcarriers assigned to the SSCH. The SSCH module 230 can include a scheduler 252 for determining nodes from the channel tree and assigning them to SSCH. The output of scheduler 252 is coupled to frequency hopping module 254. The frequency hopping module 254 maps the assigned channel tree nodes determined by the scheduler 252 to physical subcarrier allocations. The frequency hopping module 254 executes a predetermined frequency hopping algorithm.

The signal mapper 214 receives the SSCH message symbol and subcarrier assignment and maps the SSCH symbol to the appropriate subcarrier. In some embodiments, the SSCH module 230 can generate a serial message stream and the signal mapper 214 can map the serial message to its assigned subcarriers.

In some embodiments, the signal mapper 214 can interleave each of the modulation symbols over the assigned subcarriers based on the SSCH message. Modulation symbol interleaving for SSCH provides the SSCH signal with maximum frequency and interference diversity.

The output of the signal mapper 214 is coupled to a pilot module 220 for allocating a predetermined portion of the subcarrier to the pilot signal. In some embodiments, the pilot signal can include multiple subcarriers that are equally spread over substantially the entire operating band. The pilot module 220 can modulate each carrier of the OFDMA system with the corresponding data or pilot signal.

In some embodiments, the SSCH symbol is used to BPSK modulate the assigned subcarriers. In another aspect, the SSCH symbol is used to QPSK modulate the assigned subcarriers. Any modulation method can be applied in practice, but a modulation method with a constellation represented by a rotating phasor is advantageous because its magnitude does not change as a function of the symbol. is there. This modulation scheme is advantageous because the SSCH can have different offsets at the same pilot reference, which also makes demodulation easier.

The output of pilot module 220 is coupled to Inverse Fast Fourier Transform (IFFT) module 222. The inverse fast Fourier transform module 222 transforms an OFDMA carrier into a symbol in the corresponding time domain. Of course, performing a Fast Fourier Transform (FFT) is not a requirement, and it is possible to use the Discrete Fourier Transform (DFT) or other transformation method to generate symbols for the time domain. it can. The output of IFFT module 222 is coupled to a parallel / series converter 224 to transform a parallel time domain symbol into a series stream.

The series OFDMA symbol stream is coupled from the parallel / series converter 224 to the transceiver 240. In the embodiment shown in FIG. 2, the transceiver 240 is a base station transceiver that transmits a forward link signal and receives a reverse link signal.

Transceiver 240 includes forward link transmitter module 244, which converts a series symbol stream to an analog signal at the appropriate frequency for broadcasting to the access terminal via antenna 246. Transceiver 240 also includes a reverse link receiver module 242 coupled to antenna 246, which module 242 receives signals transmitted by one or more remote access terminals.

The SSCH module 230 generates SSCH messages. As mentioned earlier, SSCH messages can include signaling messages. In addition, SSCH messages can include feedback messages such as ACK messages or power control messages. The SSCH module 230 is coupled to the output of receiver module 242, and some parse the received signal to generate signaling and feedback messages.

The SSCH module 230 includes a signaling module 232, an ACK module 236 and a power control module 238. The signaling module 232 generates the desired signaling message and encodes it according to the desired coding scheme. For example, the signaling module 232 analyzes the signal received in response to the connection request and generates a connection permission message directed to the source access terminal. The signaling module 232 also generates and encodes a block allocation message for any forward or reverse link.

Similarly, the ACK module 236 generates an ACK message destined for the access terminal where the transmission was properly received. The ACK module 236 generates a unicast message, a multicast message, or a broadcast message depending on the system configuration.

The power control module 238 generates arbitrary reverse link power control messages, in part based on the received signal. The power control module 238 also generates the desired power control message.

The power control module 238 also generates a power control signal that controls the power density of the SSCH message. The SSCH module 230 power controls individual unicast messages based on the needs of the destination access terminal. In addition, the SSCH module 230 power controls unicast or broadcast messages based on the weakest forward link signal strength reported by the access terminal. The power control module 238 scales the symbols encoded from each module in the SSCH module 230. In another aspect, the power control module 238 supplies a control signal to the pilot module 220 to scale the desired SSCH symbol. The power control module 238 thus allows the SSCH module 230 to power control each SSCH message according to its needs. This provides a reduction in power overhead for SSCH.

One or more elements depicted in FIG. 2 can be integrated in a processor with integrated memory modules and / or external memory modules.

FIG. 3 is a simplified time-frequency diagram 300 of an aspect of a shared signaling channel, such as the channel generated by the SSCH module of the transmitter of FIG. The time-frequency diagram 300 details the allocation of SSCH subcarriers to two consecutive frames 310 and 320. Consecutive frames in a TDM system can have one or more interbeaning frames assigned to reverse link access terminal transmissions (not shown), but two consecutive frames 310 and 320 are in an FDM system or TDM system. Represents a continuous frame.

The first frame 310 includes three frequency bands 312a-312c, which represent the three separate subcarriers assigned to the SSCH in a particular frame. The three subcarrier allocations 312a-312c are shown to last for the entire duration of frame 310. In some embodiments, the subcarrier allocation can change during the course of frame 310. The number of times the subcarrier allocation can change in the process of frame 310 is defined by the frequency hopping algorithm and is generally less than the number of OFDM symbols in frame 310.

In the embodiment shown in FIG. 3, the subcarrier allocation varies at the frame boundary. Subsequent second frame 320 also contains the same number of subcarriers assigned to SSCH as in first frame 310. In some embodiments, the number of subcarriers assigned to the SSCH is predetermined and fixed. For example, the SSCH bandwidth overhead is fixed at some predetermined level. In another aspect, the number of subcarriers assigned to the SSCH is variable and is assigned by system control messages. Typically, the number of subcarriers assigned to SSCH does not change at a high rate.

The subcarriers mapped to SSCH are determined by a frequency hopping algorithm that maps logical node assignments to physical subcarrier assignments. In the embodiment shown in FIG. 3, the three subcarrier physical assignments 322a-322c are different in the second frame 320. As before, the subcarrier allocation is depicted as stable over the entire length of frame 320.

Figure 3 depicts the SSCHs assigned to several adjacent OFDM symbols for one or more subcarriers, but this is not all, for example symbol rate hopping schemes or blocks of adjacent subcarriers, OFDM symbols, etc. Alternatively, it can be mapped by any method, such as a combination of one or more symbols. Also, as shown in Figure 3, the resource allocation method differs between data and SSCH channels. In addition, if data transmissions are allocated to logical control channel resources, those allocations are omitted or not performed at the base station.

FIG. 4 shows a method 400 for generating a signaling message in a communication system having a shared signaling channel. A transmitter with the SSCH module shown in FIG. 2 performs this method 400. Method 400 depicts the generation of one frame of an SSCH message. Method 400 repeats this for additional frames.

Method 400 begins at block 410, where the SSCH module generates signaling messages. The SSCH module generates signaling messages in response to requests. For example, the SSCH module generates a connection permission message in response to a connection request. Similarly, the SSCH module generates a forward link or reverse link assignment block message in response to a link request or data transmission request.

The SSCH module goes to block 412 and encodes the signaling message. SSCH generates unicast messages for a particular message type, for example connection permissions. When formatting a unicast message, the SSCH module identifies the MAC ID of the destination access terminal. The SSCH module encodes the message, generates a CRC code, and attaches the CRC to the message. In addition, SSCH integrates messages for several access terminals into a single multicast or broadcast message and encodes the integrated message. The SSCH can include, for example, the MAC ID specified for the broadcast message. SSCH can generate a CRC for the integrated message and attach that CRC to the encoded message.

The SSCH module, but not necessarily, proceeds to block 414 to power control the signaling message. In some embodiments, the SSCH adjusts or standardizes the amplitude of the encoded message. In another aspect, the SSCH module can instruct the modulator to standardize the amplitude of the symbol.

The SSCH module then performs operations similar to the generation of ACK and reverse link power control feedback messages, but not necessarily. At block 420, the SSCH module generates the desired ACK message based on the received access terminal transmission. SSCH module blocks<u style="single">422</u>And encode the ACK message as, for example, a unicast message. The SSCH module goes to block 424 and adjusts the power of the ACK symbol.

The SSCH module proceeds to block 430 to generate a reverse link power control message, for example, based on the received signal strength of the individual access terminals. The SSCH module proceeds to block 432 and encodes the power control message, typically as a unicast message. The SSCH module goes to block 434 and adjusts the power of the reverse link power control message symbol.

The SSCH module goes to block 440 and, like the channel tree, determines which logical resources are allocated to the SSCH. The SSCH module goes to block 450 and maps the physical channel resource allocation to the assigned node. The SSCH module can use frequency hopping algorithms to map logical node allocations to physical channel resource allocations. Frequency hopping algorithms allow the same node allocation to create different physical channel resource allocations for different frames. Thus, the frequency hopper<u style="single">at some degree</u>interference<u style="single">Diversity</u>alike,<u style="single">A certain level</u>frequency<u style="single">Diversity</u>Can be provided.

The SSCH goes to block 460 and maps the message symbol to the assigned physical channel resource. The SSCH module interleaves message symbols between assigned physical channel resources to add diversity to the signal.

The symbol modulates the OFDM subcarrier, and the modulated subcarrier is converted into an OFDM symbol and transmitted to various access terminals. The SSCH module allows flexibility in the amount of power overhead devoted to the channel, while allowing fixed bandwidth FDM channels to be used for signaling and feedback messages.

Figure 4 shows the generation of SSCH transmissions, including signaling, acknowledgment, power control, and allocation messages, one or more of which, along with one or more other message types, replaces the arrangements disclosed here. Can be used.

FIG. 5 shows another method 500 for generating signaling messages in a communication system having a shared signaling channel. Method 500 begins at block 510, where logical control channel resources are assigned to physical channel resources. Logical control channel resources are distinct from logical traffic channel resources allocated for data transmission. In some embodiments, it is distinguished by allocating logical resources only to signaling channels. In other embodiments, these<u style="single">logic</u>Resources are reserved for signaling channels, and systems such as schedulers allocate reserved unused logical resources to signaling channels for data transmission. In addition, the logical resource can be a node in the channel tree, a hop port in the frequency hop algorithm, or other logical resource. In some embodiments, the physical channel resource corresponds to a subcarrier, an OFDM symbol, or a combination of a subcarrier and an OFDM symbol.

Resource allocation varies according to one or more frequency hopping algorithms used. These hopping algorithms vary depending on the signaling and logical resources assigned to the data channel, for example, different channel trees may be used for the logical signaling channel resource and the logical data channel resource. In addition, different types of signaling channel resources, such as signaling, affirmative response, power control, and allocation, each have different logical resources, or all of them are assigned logical resources or allocations to signaling resources. It is arbitrarily or deterministically mapped to later physical resources.

A signaling message is then generated in block 520 and encoded in block 530. The message is then sent in block 540 to the physical channel resource assigned to the logical signaling channel resource based on the mapping of the symbols corresponding to the message. A signaling message is a signaling, acknowledgment, power control, allocation, or other type of message. In addition, a single message can have a variety of signaling message types, for example, a unicast message can have signaling, acknowledgment, and power control information for a particular user.

In addition, power control of the signaling message or its symbol is performed by the SSCH module by adjusting or standardizing the amplitude of the encoded message or symbol.

Figure 5 shows the assignments that occur prior to symbol modulation and coding, but each of the three functions is independent for the other three functions, for example, vice versa or simultaneous. May be good.

In some cases, for example, when the same channel tree is used for both signaling and data logical resources such as SSCH and logical resources, the scheduler is reserved for signaling for the data channel. You can allocate the logical resources you have. In such cases, the logical resource is excluded from the communication resources assigned to the terminal. Alternatively, it can be reassigned, for example, when a data channel is assigned to a logical resource reserved for signaling, each allocation of the reserved logical resource is one or more related to the transfer destination of the data allocation. Has logical resources.

FIG. 6 shows a simplified device 600 for generating signaling messages in a communication system having a shared signaling channel. The device includes means 610 for allocating logical control channel resources to physical channel resources. Logical control channel resources are distinct from logical traffic channel resources allocated for data transmission . In some embodiments, it is distinguished by allocating logical resources only to signaling channels. In another aspect, these resources are reserved for the signaling channel, and a system, such as a scheduler, allocates the reserved unused logical resources to the signaling channel for data transmission. In addition, the logical resource is a node in the channel tree, a hop port in the frequency hop algorithm, or other logical resource. In some embodiments, the physical channel resource corresponds to a subcarrier, an OFDM symbol, or a combination of a subcarrier and an OFDM symbol.

Resource allocation varies according to one or more frequency hopping algorithms used. These hopping algorithms vary depending on the signaling and logical resources assigned to the data channel, for example, different channel trees may be used for the logical signaling channel resource and the logical data channel resource. In addition, different types of signaling channel resources, such as signaling, affirmative response, power control, and allocation, each have different logical resources, or all of them are assigned logical resources or allocations to signaling resources. It is arbitrarily or deterministically mapped to later physical resources.

The device 600 includes means 620 for generating a signaling message and means 630 for encoding the signaling message. The message is then sent by transmitter 640 to the physical channel resource assigned to the logical signaling channel resource, based on the mapping of the symbols corresponding to the message. A signaling message is a signaling, acknowledgment, power control, allocation, or other type of message. In addition, a single message can have a variety of signaling message types, for example, a unicast message can have signaling, acknowledgment, and power control information for a particular user.

In addition, power control of the signaling message or its symbol can be performed by means such as the power control module 238 of FIG.

The various logical blocks, modules, and circuits described in connection with the aspects disclosed herein are general-purpose processors, digital signal processors (general-purpose processors) designed to perform the functions disclosed herein. DSP), reduced instruction set computer (RISC), application-specific LSI (ASIC), field programmable gate array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete. It can be implemented or executed with hardware components, or a combination thereof. The general purpose processor can be a microprocessor, but as an alternative, it may be another processor, controller, microcontroller or state machine. In addition, the processor is a device with a computing function (computing). It can be achieved by a combination of devices), such as a combination of DSP and microprocessor, a combination of multiple microprocessors, a combination of DSP cores and one or more microprocessors, or other configurations of this type.

The methods, processes or algorithms described in connection with the aspects disclosed herein can be embodied directly in hardware, software running on a processor, or a combination of the two.

Software modules can be stored in RAM memory, flash memory, non-volatile memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disks, removable disks, CD-ROMs, or other storage media known in the art. The storage media can be combined with the processor, which can read and write information to and from the storage media. In addition, various methods can be performed to achieve the embodiments presented herein, and the steps can be modified. In addition, one or more processes or steps can be omitted or added. Additional steps, blocks or actions can be added at the beginning, end, or middle of an existing method, process.

The above description of the disclosed aspects is provided to allow one of ordinary skill in the art to carry out this disclosure. Various variations of these embodiments will be readily apparent to those of skill in the art, and the general principles defined herein can be applied to other forms without departing from the spirit or scope of disclosure. Therefore, disclosure is not intended to be limited to the aspects presented herein, and the broadest scope consistent with the disclosed principles and novel features should be allowed.

<figref num="1">It is a simplified functional block diagram of the communication system which has a shared signaling channel.</figref><figref num="2">FIG. 6 is a simplified functional block diagram of a transmitter that supports a shared signaling channel.</figref><figref num="3">A simplified time-frequency diagram of a shared signaling channel.</figref><figref num="4">It is a figure which shows the method of generating the signaling message in the communication system which has a shared signaling channel.</figref><figref num="5">It is a figure which shows the other method of generating a signaling message in the communication system which has a shared signaling channel.</figref><figref num="6">It is a figure which shows the simplified apparatus for generating a signaling message in the communication system which has a shared signaling channel.</figref>