RU2372749C2 - Access channel effective indication - Google Patents

Abstract

FIELD: information technologies.

SUBSTANCE: metric of geometry of direct communication line of observed transmission signals is determined. Value of channel quality indicator is determined as a function of observed transmission signals. Access sequence is chosen at random from one group of many groups of access sequences, at that each group of many groups of access sequences corresponds to different ranges of channel quality values.

EFFECT: transmission of channel quality indicator along with minimising of broadcasting channel use.

50 cl, 8 dwg, 1 tbl

Description

The invention generally relates to communication, and more particularly to data transmission in a wireless multiple-access communication system.

BACKGROUND

The access channel is used in the reverse link by the access terminal to initially establish communication with the access point. The access terminal may initiate an access attempt in order to request dedicated channels, register or perform a handover, etc. Before initiating an access attempt, the access terminal receives information from the downlink channel in order to determine the level of the most intense signal from nearby access points and enter synchronism with the time characteristics of the downlink. The access terminal is then able to decode the information transmitted by the access point over the broadcast channel regarding the selection of parameters that control the access attempt of the access terminal.

In some wireless communication systems, the access channel indicates both a test message and a message that is interpreted. In other wireless communication systems, the access channel indicates only a test message. As soon as the test message is confirmed, a message is sent that controls the access attempt of the access terminal.

In an orthogonal frequency division multiple access (OFDMA) system, an access terminal typically divides the transmission of access signals to be transmitted on the access channel into parts, transmission of the preamble and transmission of the payload. To prevent intra-cell interference due to a lack of perfect synchronization in the reverse link during transmission of the access preamble, the CDM-based transmission of the preamble can be time division multiplexed with the remainder of the transmitted signals (e.g., traffic, control, and access payload). To access the system, the access terminal then randomly selects one (pseudo-noise) PN sequence from the group of PN sequences and sends it as its preamble during the access interval.

The access point searches for any preambles (that is, all possible PN sequences) that could be transmitted during the access interval. The characteristics of the access preamble are measured in terms of the probability of collision, the probability of incorrect detection and the probability of false alarm. Collision probability indicates the probability that a particular pseudo-noise (PN) sequence is selected by more than one access terminal in the form of its preamble in the same access interval. This probability is inversely proportional to the number of preamble sequences available. The probability of incorrect detection indicates the probability that the transmitted PN sequence is not detected by the base station. The probability of a false alarm indicates the likelihood that the access point erroneously declared that the preamble was transmitted, while no preamble was actually transmitted. This probability increases with the number of preambles available.

The access point then transmits an acknowledgment for each of the detected preambles. A confirmation message may include a detected PN sequence, a correction for a synchronization error, a channel index for transmitting an access payload. Terminals from access terminals whose PN sequence is confirmed can then transmit the corresponding access payload using the assigned resource.

Since the access point does not have preliminary information about where the access terminal is located in the system (that is, what power consumption, buffer size or quality of service can be), the confirmation message is transmitted broadcast at a sufficiently high power level, so that all access terminals in this cell could decode the message. Broadcast acknowledgment is irrational since it requires a disproportionate transmit power and / or bandwidth to close the link. Thus, there is a need to send an acknowledgment message to access terminals in a given cell more efficiently.

SUMMARY OF THE INVENTION

Embodiments of the invention minimize the use of a broadcast acknowledgment channel during preamble transmission. Embodiments of the invention also take measures on how information regarding the quality of the forward link channel can be effectively signaled on the access channel during transmission of the access preamble.

In one embodiment, an apparatus and method for transmitting a channel quality indicator that minimizes the use of a broadcast channel is described. The geometry metric of the forward link of the observed transmission signals is determined. The value of the channel quality indicator is determined as a function of the observed transmission signals. The access sequence is randomly selected from one group of the multiple groups of access sequences, with each of the multiple groups of access sequences corresponding to different ranges of channel quality values.

The forward link geometry metric can be defined as a function of the observed pilot signals, noise, and / or traffic over the data channels. The number of access sequences in a plurality of access sequence groups is unevenly distributed. In an embodiment, access sequences are distributed to reflect the distribution of access terminals around the access point. In yet another embodiment, the access sequences are distributed in proportion to the number of access terminals that require a given power value to send a confirmation indicator to the access terminal.

In yet another embodiment, a method for splitting multiple access sequences is described. The probability distribution of the plurality of access terminals around the access point is determined. The probability distribution is determined as a function of a plurality of access terminals having CQI (channel quality indicator) values within specified ranges. Groups of access sequences are assigned in proportion to the probability distribution. Access sequences can be reassigned as a function of changes in the distribution of terminals around the access point.

In yet another embodiment, an apparatus and method for transmitting acknowledgment of a detected access sequence is described. Accept the access sequence. The access sequence can be found in a lookup table stored in memory to determine at least one attribute of a given access terminal (as a function of the access sequence). An attribute may be information, such as a channel quality indicator, a buffer size, and a quality of service indicator. The information is then transmitted to the access terminal, the information being appropriate and consistent with the attribute. Transmitted information may include a confirmation indicator. A confirmation indicator may be transmitted on a Shared Signaling Channel (SSCH).

Various aspects and embodiments of the invention are described in more detail below.

BRIEF DESCRIPTION OF THE DRAWINGS

The features and essence of the present invention will become more apparent from the detailed description set forth below, taken in conjunction with the drawings, throughout which the same reference characters carry out the corresponding identification and on which:

figure 1 illustrates a block diagram of a transmitter and a receiver;

2 illustrates the structure of a test access message and the sequence of a test access message;

3 illustrates a traditional call flow between an access terminal and an access point;

4 illustrates an embodiment of the invention that avoids the use of broadcast acknowledgment;

5 illustrates a cell divided using a uniform interval;

6 illustrates a diagram showing weighted division based on quantized CQI values;

7 illustrates a table stored in a memory that divides groups of access sequences into subgroups of access sequences based on a variety of factors; and

8 illustrates a flowchart for dynamically allocating access sequences.

DETAILED DESCRIPTION

The word "exemplary" is used in the materials of this application to mean "serving as an example, option or illustration." Any embodiment or construction described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments or constructions.

The techniques described herein for utilizing multiple modulation schemes for a single packet may be used for various systems, such as orthogonal frequency division multiple access (OFDMA), code division multiple access (CDMA), multiple access time division multiplexing (TDMA), frequency division multiple access (FDMA) system, orthogonal frequency division multiplexing based system channelization (OFDM), a system with one input and one output (SISO), a system with many inputs and many outputs (MIMO), and so on. These technologies can be used for systems that use incremental redundancy (IR) and systems that do not use IR (for example, systems that simply repeat data).

Embodiments of the invention avoid the use of a broadcast acknowledgment channel by forcing access terminals to indicate a parameter, such as forward link channel quality (e.g., CQI), buffer level requirements, quality of service requirements, etc., during transmission of their preambles. By forcing the access terminals to indicate the channel quality of the forward link, the access point can transmit each acknowledgment on the channel using the appropriate power value for a given access terminal or group of access terminals. In the case of an acknowledgment message transmitted to a group of access terminals, an acknowledgment message is sent to multiple access terminals that have the same or similar CQI values (within a range). Embodiments of the invention further emphasize how CQI can be effectively signaled on an access channel during transmission of an access preamble.

"Access terminal" refers to a device that provides the user with the ability to voice and / or information communication. The access terminal may be connected to a computing device, such as a laptop computer or desktop computer, or it may be a standalone device, such as a personal digital assistant. An access terminal may also be called a subscriber station, subscriber unit, mobile station, wireless device, mobile phone, remote station, remote terminal, user terminal, user agent, or user equipment. The subscriber station may be a cellular telephone, PCS telephone (personal communication system), cordless telephone, Session Initiation Protocol (SIP) telephone, wireless local loopback station (WLL), personal digital assistant (PDA), handheld device with wireless capability, or another processing device attached to the radio modem.

An “access point” refers to a device in an access network that communicates over the air interface through one or more sectors with access terminals or other access points. The access point acts as a router between the access terminal and the remaining part of the access network, which may include an IP (Internet Protocol) network by converting the received frames of the air interface to IP packets. Access points also coordinate attribute management for the air interface. The access point may be a base station, sectors of a base station and / or a combination of a base transceiver station (BTS) and a base station controller (BSC).

1 illustrates a block diagram of a transmitter 210 and a receiver 250 in a wireless communication system 200. At transmitter 210, TX data (processor) processor 220 receives data packets from data source 212. TX data processor 220 processes (eg, formats, encodes, splits, interleaves, and modulates) each data packet in accordance with a mode selected for such a packet , and generates up to T data symbol blocks for the packet. The selected mode for each data packet may indicate (1) the size of the packet (i.e., the number of information bits for the packet) and (2) the particular combination of code rate and modulation scheme to use for each data symbol block of such a packet. The controller 230 provides various control actions to the data source 212 and the TX data processor 220 for each data packet based on the selected mode. TX data processor 220 provides a stream of data symbol blocks (eg, one block for each frame), where the blocks of each packet can be interleaved with blocks for one or more other packets.

The transmitter unit (TMTR) 222 receives a stream of data symbol blocks from TX data processor 220 and generates a modulated signal. The transmitter unit 222 multiplexes pilot symbols with data symbols (eg, using time, frequency, and / or code division multiplexing) and obtains a transmit symbol stream. Each transmission symbol may be a data symbol, a pilot symbol, or a null symbol having a zero signal value. The transmitter unit 222 may perform OFDM modulation if OFDM is used by the system. The transmitter unit 222 generates a sample stream in the time domain and additionally brings it to the desired state (for example, converts to analog form, upconverts, filters and amplifies) the sample stream to form a modulated signal. The modulated signal is then transmitted from antenna 224 and through a communication channel to receiver 250.

At receiver 250, a transmitted signal is received by antenna 252, and a received signal is provided to receiver unit 254 (RCVR). The node 254 of the receiver brings to the desired state, digitizes and preprocesses (for example, OFDM demodulates) the received signal to obtain the received data symbols and the received pilot symbols. The receiver unit 254 provides the received data symbols to the detector 256, and the received pilot symbols to the channel estimator 258. The channel estimator 258 processes the received pilot symbols and provides channel estimates (e.g., channel gain estimates and SINR estimates (signal level to total interference and noise level ratios)) for the communication channel. Detector 256 performs detection on the received data symbols using channel estimates and provides detected data symbols to the RX data (receive) processor 260. The detected data symbols may be represented by a logarithmic likelihood ratio (LLR) for code bits used to generate data symbols (as described below), or other representations. Whenever a new block of detected data symbols is received for a given data packet, the RX data processor 260 processes (for example, de-interleaves and decodes) all the detected data symbols obtained for such a packet and provides a decoded packet to the data receiver 262. RX data processor 260 also checks the decoded packet and provides a packet status that indicates whether the packet was correctly decoded or in error.

Controller 270 receives the channel estimates from channel estimator 258 and the packet status from RX data processor 260. Controller 270 selects a mode for the next data packet to be transmitted to receiver 250 based on channel estimates. Controller 270 also collects feedback information. The feedback information is processed by the TX data processor 282, is additionally brought into the desired state by the transmitter unit 284, and transmitted through the antenna 252 to the transmitter 210.

At transmitter 210, the transmitted signal from receiver 250 is received by antenna 224, brought into position by receiver node 242, and further processed by RX data processor 244 to recover feedback information sent by receiver 250. Controller 230 receives received feedback information, uses ACK / NAK (confirmation / lack of confirmation) to control the IR transmission of the packet sent to the receiver 250, and uses the selected mode to process the next data packet to be sent to the receiver 250. Controllers 230 270 direct the operation at transmitter 210 and receiver 250, respectively. The nodes 232 and 272 memory provide storage for control codes and data used, respectively, by the controllers 230 and 270.

2 illustrates the structure of a test access message and the sequence 200 of a test access message. Figure 2 shows Ns of test message sequences, each test message sequence containing Np test messages. The medium access control layer (MAC) protocol transmits test access messages by instructing the physical layer to transmit the test message. With the instruction, the access channel MAC protocol provides the physical layer with a number of elements, including, but not limited to, power level, access sequence identification, PN with the pilot signal of the sector to which the access test message should be transmitted, synchronization error field and control field segment. Each test message in sequence is transmitted with increasing power until the access terminal accepts the grant of access. Transmission is terminated if the protocol received a shutdown command or if the maximum number of test messages per sequence was transmitted. Before transmitting the first test message from all sequences of test messages, the access terminal generates an inertia check, which is used to control congestion in the access channel.

FIG. 3 illustrates a conventional call flow between an access terminal and an access point 300. The access terminal 304 randomly selects a preamble, or PN sequences, from a group of PN sequences and sends a 308 preamble during an access interval to an access point 312. Upon receipt, the access point 312 then transmits 316 access grants, including broadcast acknowledgment, for each of the detected preambles. This acknowledgment is a broadcast acknowledgment transmitted at a sufficiently high power so that all access terminals in a given cell are able to decode the broadcast acknowledgment. This is considered mandatory, since the access point does not have preliminary information about where the access terminals are located in the system, and thus does not have information regarding the power level required by the access terminal to decode the broadcast acknowledgment. Upon receipt of the access grant 316, the access terminal 304 sends 320 a payload according to the specific resources allocated in the access grant.

The confirmation broadcast described above is relatively inefficient, as it requires a disproportionate transmit power and / or bandwidth to close the link. 4 illustrates an embodiment 400 of the invention that avoids the use of broadcast acknowledgment. The access terminal observes 408 transmitted signals from access points. Upon observation, the access terminal determines the power of the transmitted signals that it receives. These observations typically entail determining the quality of the forward link channel from the observed capture pilot transmissions or pilot signal transmissions as part of a shared signaling channel (SSCH) channel.

Access terminal 404 then randomly selects a preamble, or access sequence, from the group of access sequences and sends the preamble 410 to access point 412. This preamble is transmitted along with some channel quality assurance (CQI) of the forward link. CQI information may be transmitted in the form of a preamble inside or attached to it. In another embodiment, the access sequence is randomly selected from a plurality of access sequence groups, where each access sequence group is intended for a range of CQI values. For example, the forward link channel quality indications may be the observed pilot power. The observed pilot power may be quantized with respect to the CQI values based on a given set of values. Thus, a predetermined power range of a received pilot may correspond to a predetermined CQI value. Accordingly, access point 412 may determine the CQI of a given access terminal according to the advantage of the access sequence selected by the access terminal.

Since the access terminal sends a forward link channel quality indicator during its initial access attempt with the access point 412, the access point 412 has the confirmation necessary to transmit 416 each acknowledgment on the channel using the appropriate power value for the indicated access terminal 404. In an embodiment, an acknowledgment message may be sent to a group of access terminals having the same or similar CQI values. This can be accomplished through the use of SSCH. Thus, based on the power level necessary for the access terminal to successfully receive the transmitted signal, the access point sends an acknowledgment message in the appropriate SSCH message segment.

In addition to the CQI information, the access terminal may send other information of interest to the access point during the initial access phase. For example, the access terminal may send a buffer level indicator indicating the amount of data that the access terminal intends to forward to the access point. With this confirmation, the access point is able to appropriately determine the size of the initial resource assignments.

The access terminal may also send information regarding priority groups or quality of service. This information can be used to prioritize access terminals in case of limited access point bandwidth or system congestion.

Upon receipt by the access terminal of an access grant message, access terminal 404 sends 420 a payload according to the resources defined in the access grant message. By receiving additional information during the initial access phase, the access point will be able to take advantage of the awareness of CQI information, buffer level and quality of service as part of the access grant message.

5 illustrates a cell 500 divided using a uniform interval. The cell is divided into a number of regions R , and each region is determined by the possession of the probability of the observed metrics within a given region. In an embodiment, observations of forward link geometry are used. For example, metrics such as C / I may be used, where C is the received pilot power and I is the observed noise. C / (C + I) may also be used. In other words, some measurement is used that uses the observed signal power and noise. These observable metrics correspond to given CQI values or ranges of values that thus define an area. For example, region R ₁ defines a region having CQI values corresponding to power and / or noise levels greater than P ₁ . Region R ₂ defines a region having CQI values corresponding to power and / or noise levels, provided that P ₂ > R ₂ > P ₁ . Similarly, the region R ₃ defines a region having CQI values corresponding to power and / or noise levels from the condition that P ₃ > R ₃ > P ₂ , and so on. The region R _N-1 has CQI values corresponding to power and / or noise levels, provided that they fall into the range P _x > R _N-1 > P _y . Similarly, the region R _N has CQI values corresponding to power and / or noise levels observed < P _x .

Theoretically, according to the choice of transmitting one of the N possible preamble sequences, up to log ₂ (N) bits of information can be transmitted. For example, when N = 1024, as many bits can be transmitted as in log ₂ (1024) = 10. Thus, by choosing which sequence of the preamble to transmit, it is possible to transmit user-dependent information as part of the transmission of the preamble.

A widely used technology is to separate N sequences of preambles into M separate sets labeled {1, 2, ..., M }. In order to signal one of the log ₂ (M) options (i.e., log ₂ (M) bits), a sequence in the proper set is selected and transmitted. For example, to signal an index k ∈ {1, 2, ..., M } of a message, (randomly) a sequence in the kth set is selected and transmitted. Provided that the receiver is correctly detected, the transmitted information (i.e., a message in log ₂ (M) bits) can be obtained by the set index to which the received sequence belongs.

In a uniform division strategy, N sequences of the preamble are evenly divided into M groups (i.e., each group contains N / M sequences). Based on the measured CQI value, one of the preamble sequences from the appropriate set is selected and transmitted. The collision probability, in this case, depends on the mapping / quantization of the measured CQI and the number of simultaneous access attempts.

This can be illustrated by considering a simple 2-level quantization of CQI (i.e., M = 2), with Pr ( M (CQI) = 1) = α and Pr ( M (CQI) = 1) = α , where M (x) - a quantization function that maps the measured CQI value to one of two levels.

With evenly divided access sequences, N preamble sequences are divided into two sets with N / 2 sequences in each set. As an example, suppose there are two simultaneous access attempts (that is, exactly two access terminals are trying to access the system in each access interval). Collision probability set according to

With a probability of α ^2, two access terminals feel the need to send M = 1 (that is, both of them have a level = 1 of quantized CQI). Since there are N / 2 sequences of preambles for selection from the first set, the probability of a collision (assuming that both access terminals select their sequence from this set) is 1 / (N / 2). Following the same logic, a collision probability for another set can be derived.

Thus, the total collision probability depends on the parameter α and the number of simultaneous access attempts. The probability of collision can be as high as 2 / N (α = 0.1) or as low as 1 / N (α = 0.5). Thus, in this case, α = 0.5 is the best choice. However, it is not clear whether the quantization function CQI, which has the result α = 0.5, is the optimal function.

The access point will transmit a confirmation channel at the power level required to complete the communication link, which is indicated by the CQI level. In this example, with probability α, the access point should transmit at a power corresponding to that of the broadcast channel, and with probability 1-α, the access point can transmit at slightly lower power. So, with α = 0.5, the access point should broadcast a confirmation channel half the time. On the other hand, when choosing α = 0.5, the access point is forced to broadcast the confirmation channel less often, but entailing an increase in the transmit power in the remaining time and a higher overall probability of collision.

6 is a diagram showing weighted division 600 based on quantized CQI values. The area is divided into different areas that do not have an equal interval, but rather are divided based on quantized CQI values that are weighted. By weighting the regions, additional sequences of preambles are available in regions that are more likely to have access terminals located in that region (i.e., a higher mass function). For example, regions 604, 608, and 612 are large regions that can correspond to the large number of access sequences available. Conversely, areas 616 and 620 are smaller areas that can show fewer users present and, accordingly, fewer available access sequences. Thus, the areas can be divided if there is some preliminary information regarding the distribution of C / I or the received power in the prescribed range in this cell. It is assumed that geographical areas may not always represent user concentrations within given CQI ranges. Rather, graphical representations of the location at non-uniform intervals should indicate an uneven distribution of access sequences over a given area of the cell.

In an embodiment, the probabilistic distribution of access terminals within a cell may be dynamic based on the distribution of access terminals over time. Accordingly, certain divided regions may be larger or smaller based on the absence or presence of access terminals at a given time of the day, or otherwise be adjusted as a function of the concentration of access terminals existing in the region of a given CQI.

So, the sequences available for initial access are divided by the number N of sections. The access terminal determines the partition that should be used to attempt access based on at least the strength of the observed pilot and the level of the buffer. It is contemplated that a partition may also be determined by a number of other factors, such as packet size, type of traffic, bandwidth demand, or quality of service. Once a section is defined, access terminals select the sequence ID (identifier) using uniform probability over that section. Of the available access sequences, a subset (subset) of sequences is reserved for active set operations, and another subset of the sequences is available for initial access. In one embodiment, sequences 0, 1, and 2 are reserved for active recruitment operations, and sequences from 3 to the total number of access sequences are available for initial access.

The size of each section is determined by the section field of access sequences in the system information block. This is typically part of a sector setting. Particular section number N contains sequence identifiers ranging from a lower threshold value, a lower N section, to an upper threshold value, an upper N section. Both thresholds are determined using the partition size partially provided in table 1 below.

Access Sequences Section Partition size N (N - 1 to 8) one 2 3 four 5 6 7 8 00000 0 0 0 0 0 0 0 0 00001 S2 S2 S2 S2 S2 S2 S2 S2 00010 S3 S3 S S1 S1 S1 S1 S1 00011 S1 S1 S1 S3 S3 S3 S1 S1 00100 S1 S1 S1 S1 S1 S1 S3 S3 00101 S3 S1 S1 S3 S1 S1 S3 S1 00101 S1 S3 S1 S1 S3 S1 S1 S3 00110 S1 S1 S3 S1 S1 S3 S1 S1 00111 S3 S3 S1 S3 S1 S1 S1 S1 01000 S1 S1 S1 S3 S3 S1 S3 S1

Thus, in this embodiment, the access terminal selects its pilot level based on the ratio measured in decibels of the power of the capture pilot from the sector where the access is being made to the total power received in the time interval of the capture channel. The pilot thresholds are determined based on the pilot field intensity of the system information message.

Embodiments describe a technique by which access sequence space is partitioned according to quantized CQI statistics. More accurately,

P = [ p ₁ p _2. .. p _M ]

is the probability function of the masses of the quantized values of CQI, where

Pr ( CQI = 1) = p ₁ , Pr ( CQI = 2) = p ₂ , ..., Pr ( CQI = M ) = p _M.

The access sequence space is then partitioned to obtain a similar probabilistic mass function. That is, the ratio of the number of access sequences in each set to the total number of access sequences should be proportional, provided that

where N _k is the number of access sequences in the set K∈ {1,2, ..., M }.

In the example describing 2-level quantization of CQI, the function leads to the following:

Pr (M ( CQI ) = 1) = α and Pr (M ( CQI ) = 2) = 1- α

The number of access sequences in each set, therefore, are ( α ) N and (1- α ) N, respectively. The resulting collision probability is

which is the smallest possible chance of a collision.

For a more general setup, with M possible levels of CQI and U simultaneous attempts, the analytic expression of the probability of collision becomes more complex.

In another example, consider M = 6, U = 8, and N = 1024. Assume that the CQI values are quantized in 4-5 dB steps. The quantized CQI values are set according to [-3, 1, 5, 10, 15, 20] dB with the following probabilistic mass function [0.05, 0.25, 0.25, 0.20, 0.15, 0.10] . That is, 5% of the time, users will report CQI values lower than -3 dB, 25% of the time with CQI values between -3 and 1 dB, and so on. The access point can then adjust the power for the acknowledgment channel based on the reported CQIs.

Using the proposed access sequence separation technology, the resulting collision probability is approximately 2.5%. In comparison, the probability of collision using uniform separation of access sequences is 3.3%. However, in order to obtain a similar probability of a collision when uniform separation of access sequences is used, the total number of sequences must be increased by 25%, to 1280. Accordingly, a larger number of search access sequences is transformed directly into a higher complexity and a higher probability of false alarm.

This separation strategy can also be used when signaling other information, such as packet size, traffic type, and bandwidth requirement, over the access channel. This is practically useful when the access channel (a portion of the preamble) is used as a means to allow the user to return to the system or request resources. If the information regarding statistics on the information to be transmitted is known (for example, the number of times when a certain connection (http, ftp, SMS) is requested or how much bandwidth is often required, etc.), then this information may be used to determine the partition of the space of sequences of access preambles.

7 illustrates a table 700 stored in memory that divides groups of access sequences into subgroups of access sequences based on a variety of factors. Factors include CQI ranges, buffer level, quality of service, packet size, bandwidth requirement, or other factors. The number of access sequences in a given subgroup can initially be determined by the supported statistics of the past concentration of users in a given cell as a function of the factors taken into account. Thus, each cell may have at its disposal a predetermined distribution of multiple access sequences for combinations of various factors. With this method of action, the probability of collision of multiple users choosing the same access sequence is minimized.

In an embodiment, the number of access sequences assigned to various combinations of factors can be dynamically changed based on changes in the composition of user needs. So, if more users migrate to an area with CQI within a given range and buffer level of a certain value, as well as various other factors, additional access sequences can be assigned to such an area. The dynamic allocation of access sequences thus reproduces a scenario by which collision probability is minimized.

FIG. 8 illustrates such a flow of operations 800. 804 initial sections are set, thereby dividing the plurality of access sequences into a number of access sequence groups. These groups can be based on ranges of CQI values. In an embodiment, the initial setup may be based on uniform distribution of access sequences. In another embodiment, the size of the initial separation may be based on historical data. A counter 808 counts access attempts in each subset. The counter can track access attempts over time to determine if there are patterns of changes in the heavy or light load factor. Based on these access attempts in time, 812 access attempts in predetermined subsets can be updated. The expected value can be represented by the following equation:

E _m : = (1 -β ) E _m + βa _m ( a _m -1)

where E _m is the expected value, a _m is the number of access sequences in this subset, and β is the elimination factor. The aftereffect factor recursively calculates the average, which gives more weight to newer data and less weight to less new data.

Based on the new expected value, 816 a new subset size can be determined. In an embodiment, the size of the subset is defined by the following equality:

where N _m is the new size of the subset, E _k is the "old" mathematical expectation of the k-th subset, m is the given subset of M aggregate subsets.

A determination is made 820 as to whether the newly determined size of the subset is substantially different than the previously established size of the subset. The threshold value for what takes effect is “substantially different” is configurable. If a determination is made that the newly determined size of the subset is substantially different 824, then the sizes of the subsets are reset. If not (828), the current subset sizes are saved 832.

Various aspects and features of the present invention have been described above with respect to individual embodiments. As used in the materials of this application, the terms “contains”, “comprising”, or any other variants thereof are meant to be interpreted as non-exclusively encompassing the elements or limitations that accompany these terms. Accordingly, a system, method, or other embodiment that contains a set of elements is not limited to only such elements and may include other elements not explicitly listed or not specific to the claimed embodiment.

Although the present invention has been described with reference to specific embodiments, it should be understood that the embodiments are illustrative and that the scope of the invention is not limited to these embodiments. Numerous variations, modifications, additions, and enhancements are possible with respect to the embodiments described above. It is intended that these variations, modifications, additions and improvements fall within the scope of the invention, which is detailed in the following claims.

Claims (50)

1. The method of determining the indicator of channel quality in a wireless communication system, which consists in the fact that:
determine the metric of the observed transmission;
determining a channel quality estimate based on at least a metric of the observed transmission and
randomly select the access sequence from one group of the multiple groups of access sequences, the multiple groups of access sequences corresponding to different ranges of channel quality values, and the selected access sequence comes from a group of multiple groups corresponding to a certain channel quality estimate. 2. The method according to claim 1, in which when determining the metric, the power of the observed pilot signal is additionally determined. 3. The method according to claim 1, in which when determining the channel quality estimate, the ratio of the received pilot signal power to noise is additionally determined. 4. The method according to claim 1, in which when determining the channel quality estimate, the ratio of the received pilot signal power to the sum of the received pilot signal power and noise is additionally determined. 5. The method of claim 1, wherein the plurality of access sequences in the plurality of groups of access sequences are distributed unevenly. 6. The method according to claim 1, in which additionally transmit the selected access sequence. 7. The method according to claim 6, in which when transmitting, additionally transmit in accordance with a frequency division multiplexing (FDM) scheme. 8. The method according to claim 6, in which when transmitting additionally carry out the transfer in accordance with the multiplexing scheme with code division multiplexing (CDM). 9. The method according to claim 6, in which when transmitting, additionally transmit in accordance with an orthogonal frequency division multiple access (OFDMA) multiple access scheme. 10. The method according to claim 1, in which when choosing additionally select information indicating the requirements of the access terminal. 11. The method according to claim 10, in which when selecting information, additionally select the needs of the level of the information buffer, the quality of service requirements, the quality indicator of the channel of the direct communication line. 12. A device for determining a channel quality indicator in a wireless communication system, comprising:
a receiver configured to receive observed transmissions;
a processor configured to determine an observable transmission metric and determine a channel quality estimate as a function of at least one observable transmission metric;
a memory element configured to store a plurality of groups of access sequences, wherein the plurality of groups of access sequences corresponds to different ranges of channel quality values; and
a selector configured to randomly select an access sequence from a group of multiple groups corresponding to a certain channel quality value. 13. The device according to item 12, in which the processor is additionally configured to determine the ratio of the received power of the pilot signal to noise. 14. The device according to item 12, in which many access sequences in many groups of access sequences are distributed unevenly. 15. The device according to item 12, further comprising a transmitter configured to transmit the selected access sequence. 16. The device according to clause 15, in which the transmitter is further configured to transmit in accordance with the frequency division multiplexing (FDM) scheme. 17. The apparatus of claim 15, wherein the transmitter is further configured to transmit in accordance with a code division multiplexing (CDM) scheme. 18. The device according to 14, in which the transmitter is further configured to transmit in accordance with a multiple access scheme with orthogonal frequency division multiplexing (OFDMA). 19. The device according to claim 11, in which the selector is further configured to select information indicative of access terminal requirements. 20. The device according to claim 19, in which the information indicating the requirements of the access terminal contains a buffer level, quality of service requirements, a quality indicator of the forward link channel. 21. Device for determining the channel quality indicator in the system
A wireless connection comprising:
means for determining the power level of the observed transmission;
means for determining the value of the channel quality indicator (CQI) as a function of the power level of the observed transmission and
means for randomly selecting an access sequence for one group of multiple groups of access sequences, moreover, many groups of access sequences correspond to different ranges of CQI values, and the selected access sequence comes from a group of many groups corresponding to a specific CQI value. 22. The device according to item 21, in which the means for determining the power level further comprises means for determining the power level of the observed pilot signal. 23. The device according to item 21, in which many access sequences in many groups of access sequences are distributed unevenly. 24. The device according to item 21, further containing means for transmitting the selected access sequence. 25. The device according to paragraph 24, in which the means for transmitting further comprises means for transmitting in accordance with the frequency division multiplexing (FDM) scheme. 26. The device according to paragraph 24, in which the means for transmitting further comprises means for transmitting in accordance with a multiplexing scheme with code division multiplexing (CDM). 27. The device according to paragraph 24, in which the means for transmitting further comprises means for transmitting in accordance with the multiplexing scheme with orthogonal frequency division multiplexing (OFDM). 28. The device according to paragraph 24, in which the means for transmitting further comprises means for transmitting in accordance with a multiple access scheme with orthogonal frequency division multiplexing (OFDMA). 29. The device according to item 21, in which the means for selection further comprises means for selecting information indicating the requirements of the access terminal. 30. The device according to clause 29, in which the means for selecting information further comprises means for selecting information regarding the needs of the level of the information buffer, the requirements of the quality of service and / or quality indicator of the channel of the direct communication line. 31. A method for transmitting information regarding the needs of an access terminal in a wireless communication system, the method comprising:
determine the received power level of the observed pilot signal;
determining the value of the channel quality indicator (CQI) as a function of the received power level and
randomly select the access sequence from one group of the many groups of access sequences, while many groups of access sequences correspond to many specified factors. 32. The method of claim 31, wherein the predetermined factors include one or more of the following: CQI value ranges, buffer level ranges, packet size, traffic type, bandwidth requirement, and quality of service indicator ranges. 33. A method for transmitting a channel quality indicator (CQI) in a wireless communication system, the method comprising:
determine the power level of the observed pilot signal;
determining a CQI value in the form of a function of the power level of the observed pilot signal;
randomly select an access sequence from one group from a plurality of groups of access sequences, while a plurality of groups of access sequences corresponds to different CQI values;
attach the CQI value to the selected access sequence and
transmit the access sequence and CQI value. 34. The method of separation of multiple access sequences, which consists in the fact that:
determining a probabilistic distribution of a plurality of access terminals around an access point, wherein a probabilistic distribution is a function of a plurality of access terminals divided into a plurality of subgroups, each subgroup being categorized as a function of CQI values within a given range; and
assign groups of access sequences in proportion to the probability distribution. 35. The method according to clause 34, in which further reassign the access sequence as a function of changes in the distribution of access terminals around the access point. 36. A device for transmitting information regarding the needs of an access terminal in a wireless communication system, comprising:
means for determining a received power level of the observed pilot signal;
means for determining the value of the channel quality indicator (CQI) as a function of the received power level and
means for randomly selecting access sequences from one group from a plurality of access sequence groups, wherein the plurality of access sequence groups corresponds to a plurality of predetermined factors. 37. The device according to clause 36, in which the specified factors include one or more of the following: ranges of CQI values, ranges of buffer levels, packet size, traffic type, bandwidth requirement and ranges of indicators of quality of service. 38. Device for transmitting a channel quality indicator (CQI) in a system
A wireless connection comprising:
means for determining the power level of the observed pilot signal;
means for determining a CQI value as a function of the power level of the observed pilot signal;
means for randomly selecting access sequences from one group from a plurality of access sequence groups, wherein the plurality of access sequence groups corresponds to different CQI values;
means for attaching the CQI value to the selected access sequence; and
means for transmitting the access sequence and CQI values. 39. An apparatus for separating multiple access sequences, comprising:
means for determining a probability distribution of a plurality of access terminals around an access point, the probability distribution being a function of a plurality of access terminals divided into a plurality of subgroups, each subgroup being categorized as a function of CQI values within a given range; and
means for assigning groups of access sequences in proportion to the probability distribution. 40. The device according to § 39, further comprising means for reassigning the access sequence as a function of a change in the distribution of access terminals around the access point. 41. A method for transmitting confirmation of a detected access sequence in a wireless communication system, the method comprising:
accept the access sequence;
determining at least one attribute of a given access terminal as a function of the access sequence and
transmit information corresponding to at least one attribute. 42. The method according to paragraph 41, in which the attribute is at least one of the following: channel quality indicator, buffer level indicator, priority indicator and quality of service indicator;
determining a probabilistic distribution of a plurality of access terminals around an access point, wherein a probabilistic distribution is a function of a plurality of access terminals divided into a plurality of subgroups, each subgroup being categorized as a function of CQI values within a given range; and assign groups of access sequences in proportion to the probability distribution. 43. The method according to paragraph 41, in which when transmitting information, an additional confirmation indicator is transmitted. 44. The method according to item 43, in which additionally transmit a confirmation indicator on a shared signaling channel (SSCH). 45. The method according to item 44, in which the confirmation indicator is included in a specific segment of the shared signaling channel (SSCH), wherein the SSCH segment is divided based on the transmit power necessary for the successful receipt of the confirmation indicator. 46. A device for transmitting confirmation of a detected access sequence in a wireless communication system, comprising:
means for receiving an access sequence;
means for determining at least one attribute of a given access terminal as a function of the access sequence and
means for transmitting information commensurate with at least one attribute. 47. The device according to item 46, in which the attribute is at least one of the following: channel quality indicator, buffer level indicator, priority indicator and quality of service indicator. 48. The device according to item 46, in which the means for transmitting information further comprises means for transmitting a confirmation indicator. 49. The device according to p, optionally containing means for transmitting a confirmation indicator on a shared signaling channel (SSCH). 50. The device according to p, in which the confirmation indicator is included in a specific segment of a shared signaling channel (SSCH), while the SSCH segment is divided based on the transmission power necessary for the successful reception of the confirmation indicator.

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