HK1094920B - Method and apparatus for power allocation to control channels in a communication system - Google Patents

Description

Method and apparatus for power allocation for control channels in a communication system

Claiming priority in accordance with 35U.S.C. § 119

This application claims priority from provisional application No. 60/490,338 entitled "method and apparatus for control channel power allocation in a communication system" filed on 25/7/2003 and assigned to the assignee hereof, and hereby incorporated by reference in its entirety for all purposes.

Technical Field

The present invention relates to communication in a wireless communication system. More particularly, the present invention relates to a method and system for power allocation to control channels in such a communication system.

Background

Communication systems have been developed that are capable of transmitting information signals from an origination station to a physically different destination station. In transmitting an information signal from an origination station using a communication channel, the information signal is first converted into a form suitable for efficient transmission over the communication channel. The conversion, or adjustment, of the information signal includes varying a parameter of the carrier wave in accordance with the information signal and causing the spectrum of the resulting modulated carrier wave to be confined within the bandwidth of the communication channel. At the destination station, the original information signal is reconstructed from the modulated carrier wave received over the communication channel. Typically, such reconstruction is accomplished by using a process that is the inverse of the modulation process employed by the origination station.

Appropriate power allocation for the control channels supporting reverse link transmission is required. And it is desirable that MAC channel power not be the limiting factor in supporting a large number of reverse link users simultaneously. Because the MAC channel will form two bursts immediately before or after the pilot burst (pilotburst) in a given half-time-slot, there is a finite amount of time available to allocate MAC channel power to the control channel. It is desirable to ensure that the limit on the number of users that can be simultaneously supported is not due to the MAC channel power but rather due to the reverse link capacity. Moreover, a communication system may need to support both legacy access terminals, i.e., access terminals that utilize reverse link transmissions in compliance with a standard such as the IS-856 standard, and new types of access terminals, i.e., access terminals that utilize reverse link transmissions in compliance with a standard that IS compatible with the IS-856 backwards. Accordingly, there is a need in the art for an apparatus and method for power allocation for control channels in such a communication system.

Disclosure of Invention

In one embodiment of the present invention, the above-mentioned need is met by a method of controlling channel power allocation, the method comprising: the method includes classifying a plurality of access terminals into a plurality of bins (bins) in an order of increasing required Media Access Control (MAC) channel power, classifying access terminals requiring equal MAC channel power in order of decreasing forward link signal-to-interference-and-noise ratio (FL-SINR) if the MAC channel power required by two or more access terminals is equal, and determining total available ARQ power based on total MAC channel power, total power allocated to Reverse Power Control (RPC) channels, and total power allocated to Reverse Activity Bit (RAB) channels.

Drawings

FIG. 1 shows a conceptual block diagram of a communication system;

fig. 2 illustrates a simplified reverse link structure for a new class of access terminals;

FIG. 3 shows time slots in a forward link structure;

FIG. 4 shows a flow diagram of an embodiment of a method of power allocation for control channels;

FIGS. 5A-C illustrate a flow diagram of a more specific embodiment of a method of power allocation for control channels;

fig. 6 illustrates an access terminal; and

fig. 7 shows an access point.

Detailed Description

Fig. 1 shows a schematic diagram of a typical Code Division Multiple Access (CDMA) communication system. Access point 100 transmits data to access terminal 104 over forward link 106(1) and receives data from access terminal 104 over reverse link 108 (1). Similarly, access point 102 transmits data to another access terminal 104 over a forward link 106(2) and receives data from the access terminal 104 over a reverse link 108 (2). Data transmission on the forward link occurs from one access point to one access terminal at or near the maximum rate that can be supported by the forward link and the communication system. Additional channels for the forward link, such as control channels, may be transmitted from multiple access points to an access terminal. Reverse link data communication may be transmitted from one access terminal to one or more access points. The access point 100 and the access point 102 are connected to an access network controller 110 through backhaul (backhaul)112(1) and 112 (2). The "backhaul" is the communication link between the controller and the access point. Although fig. 1 shows only two access terminals and one access point, this is for illustration only and the communication system can include a plurality of access terminals and access points.

After registration, which allows the access terminal to access the access network, the access terminal 104 and one of the access points (e.g., access point 100) establish a communication link using a predetermined access procedure. The access terminal 104 can receive data and control messages from the access point 100 and can transmit data and control messages to the access point 100 in a connected state resulting from a predetermined access procedure. The access terminal 104 continually searches for other access points that can be added to the access terminal's 104 active set. The active set includes a list of access points capable of communicating with the access terminal 104. When such an access point is found, the access terminal 104 calculates a quality metric for the forward link of the access point, which may include a signal-to-interference-and-noise ratio (SINR). The SINR may be determined in accordance with the pilot signal. The access terminal 104 searches for other access points and determines SINRs for signals transmitted from each of those access points and signals received at the access terminal 104. At the same time, the access terminal 104 calculates a quality metric for the previous link for each access point in the access terminal's 104 active set. If the forward link quality metric from a particular access point is above a predetermined add threshold or below a predetermined drop threshold for a predetermined length of time, the access terminal 104 reports this information to the access point 100. Subsequent messages from the access point 100 may direct the access terminal 104 to add that particular access point to the access terminal's 104 active set or to remove that particular access point from the access terminal's 104 active set.

The access terminal 104 selects a serving access point from the active set of the access terminal 104 based on a set of parameters. The serving access point is the access point selected for data communication with a particular access terminal or is the access point that is communicating data to the particular access terminal. The set of parameters may include, for example, any one or more of current and previous SINR measurements, bit error rates, packet error rates, and any other known parameters. Thus, for example, the serving access point may be selected based on the largest SINR measurement. The access terminal 104 then broadcasts a data request message (DRC message) on a data request channel (DRC channel). The DRC message can contain the requested data rate or, alternatively, an indication of the quality of the forward link, such as a measured SINR, bit error rate, packet error rate, etc. The access terminal 104 may direct the broadcast of the DRC message to the specified access point by using a code that uniquely identifies the specified access point. Typically, the code comprises a walsh code. The DRC message symbol is exclusively or (xor) operated with a unique code. This XOR operation is referred to as code-covering of the signal. Since each access point in the access terminal's 104 active set is identified by a unique walsh code, only selected access points that perform the same XOR operation as performed by the access terminal 104 with the correct walsh code can correctly decode the DRC message.

Data to be transmitted to the access terminal 104 arrives at the access network controller 110. The access network controller 110 may then send the data over the backhaul 112 to all access points in the access terminal 104 active set. Alternatively, the access network controller 110 may first determine which access point was selected by the access terminal 104 as the serving access point and then send the data to the serving access point. The data is stored in a queue (queue) at the access point. The one or more access points then transmit the paging message to the access terminal 104 on respective control channels. The access terminal 104 demodulates and decodes the signals on the one or more control channels to obtain the paging message.

At each forward link interval, the access point may schedule transmission to any one of the access terminals that received the paging message. An exemplary method for Power Allocation for Reverse Power Control (RPC) channels is described in U.S. patent application serial No. 10/263,976 entitled "Power Allocation for Power control bits in a Cellular Network," filed on 2002, 10/2, which is assigned to the assignee of the present application. The access point utilizes the rate control information received in the DRC message from each access terminal to efficiently transmit forward link data at the highest rate possible. Because the data rate may vary, the communication system operates in a variable rate mode. The access point determines the rate at which data is to be transmitted to the access terminal 104 based on the most recent value of the DRC message received from the access terminal 104. In addition, the access point uniquely identifies transmissions to the access terminal 104 with a spreading code that is unique to that mobile station. Such a spreading code IS a long Pseudo Noise (PN) code, such as the spreading code defined by the IS-856 standard.

The access terminal 104 to which the data packet is intended receives and decodes the data packet. Each data packet is associated with an identifier, such as a sequence number, that is used by the access terminal 104 to detect loss or duplication of transmission. In such a case, the access terminal 104 communicates the sequence number of the missing data packet via the reverse link data channel. The access network controller 110, which receives the data message from the access terminal 104 via the access point in communication with the access terminal 104, then indicates to the access point which data units were not received by the access terminal 104. The access point then arranges for retransmission of such data packets.

When the communication link between an access terminal 104 operating in a variable rate mode and an access point 100 degrades below a predetermined reliability level, the access terminal 104 first attempts to determine whether another access point in the variable rate mode can support an acceptable data rate. If the access terminal 104 determines that there is such an access point (e.g., access point 102), then a redirection of the access point 102 to a different communication link occurs. The term re-pointing is a process of selecting a sector that is different from the currently selected sector and is a member of the access terminal's active list. Data transmission continues from access point 102 in the variable rate mode.

Such degradation of the communication link may be caused by, for example, the movement of the access terminal 104 from the coverage area of the access point 100 to the coverage area of the access point 102, shadowing, fading, and other well-known causes. Optionally, when a communication link between the access terminal 104 and another access point (e.g., access point 102) becomes available, which may achieve a higher throughput than the currently used communication link, a redirection to the access point 102 connected to a different communication link occurs, and data transmission continues from the access point 102 in the variable rate mode. If the access terminal 104 does not detect an access point that is capable of operating in the variable rate mode and supporting an acceptable data rate, the access terminal 104 transitions to the fixed rate mode. In such a mode, the access terminal transmits at one rate.

The access terminal 104 estimates the communication links with all candidate access points for both variable rate and fixed rate data patterns and selects the access point that yields the highest throughput.

If the sector is no longer a member of the access terminal's 104 active set, the access terminal 104 may switch from the fixed rate mode back to the variable rate mode.

Reverse link

A communication system in accordance with the above-described concepts may need to support both legacy access terminals that utilize reverse link transmissions that conform to one standard (i.e., IS-856) and new access terminals that utilize reverse link transmissions that conform to another standard, i.e., the reverse link transmissions described in the above-mentioned co-pending application serial numbers 10/280,740 and 10/305,338.

The reverse link 200 of the new access terminal is shown in fig. 2. The new access terminal also builds a packet into a frame containing 16 slots. The frame is then transmitted in at least two non-contiguous (non-contiguous) subframes, wherein each subframe contains at least one slot. The reverse link overhead channels 206 include: a Pilot Channel (PC), an Auxiliary Pilot Channel (APC), a Data Request Channel (DRC), an Acknowledgement Channel (ACK), a data source control channel (DSC), and a reverse rate indication channel (RRI). As shown in fig. 2, a packet is transmitted in four non-contiguous subframes 202, each subframe comprising four slots. Overhead channel 206 is continuously transmitted.

Reverse link processing

The access terminal receives the first subframe and attempts to decode the user data contained in the subframe. The access terminal may then transmit a response based on the decoded result. The response is an Acknowledgement (ACK) if the decoding is successful and a Negative Acknowledgement (NAK) if the decoding is unsuccessful.

The response is received at the access point before the next subframe is transmitted. Subsequently, if the access point receives the ACK, the transmission of all remaining subframes is interrupted and the access point may transmit to the subframes of the packet that have not been transmitted by then.

Forward link structure

Fig. 3 shows time slots in a forward link structure 300. It will be appreciated that the durations, chip lengths, ranges of values described below are given by way of example only and that other durations, chip lengths, ranges of values may be used without departing from the basic principles of operation of the communication system.

The forward link 300 is defined in terms of frames. A frame is a structure that includes 16 slots 302, and each slot 302 is 2048 chips long, corresponding to a slot duration of 1.66ms and a frame duration of 26.66 ms. Each time slot 302 is divided into two half-time slots 302a, 302b, and pilot channel bursts 304a, 304b are transmitted within each half-time slot 302a, 302 b. Each pilot channel burst 304a, 304b is 96 chips long, centered approximately at the midpoint of its associated half-time slot 302a, 302 b. The pilot channel bursts 304a, 304b comprise a pilot channel signal covered by a code (e.g., a walsh code with index 0). The pilot channel is a common control channel that is broadcast to all remote stations, i.e., the information conveyed using the pilot channel is intended to be received and used by all remote stations. Typically, the control channel carries overhead data, but may also carry user data. The term overhead data is information that enables operation of entities in the communication system, e.g., call maintenance signaling, diagnostic and reporting information, and the like.

The forward Medium Access Control (MAC) channel 306 forms two bursts that are transmitted immediately after and before the pilot burst 304 of each half-slot 302. The MAC includes a maximum of 128 code channels that are orthogonally covered by a 128-ary code, such as a walsh code. Each code channel is identified by a MAC index having a value between 1 and 128 and which identifies a unique 128-order cover walsh code.

A Reverse Power Control (RPC) channel is used to adjust the reverse link signal power for each subscriber station. Thus, the RPC channel is a control channel dedicated to the subscriber station, i.e., the power control information transmitted on a particular RPC channel will be received and used by a remote station. RPCs are assigned to one of the available MACs, e.g., a MAC with a MAC index between 11 and 127. In one embodiment, MAC indices 0-1 are reserved, MAC indices 2-3 are used for control channels, MAC index 4 is used for Reverse Activation (RA) channels, MAC index 5 is used for broadcast, MAC indices 6-10 are used for multi-user packets, and MAC indices 11-127 are used for RPC, DRC Lock (DRC Lock), and ARQ. In one embodiment, the MAC indices 64-67 are also used for the control channels.

The Reverse Activity (RA) channel is used to adjust the reverse link rate of data for each subscriber station by transmitting a stream of reverse link activity bits (RABs), and as such, the RA channel is a control channel dedicated to the subscriber station. The RA channel is assigned to one of the available MACs, e.g., MAC index 4.

The payload of the forward link traffic channel or control channel is transmitted in the remaining portion 308a of the first half-slot 302a and the remaining portion 308b of the second half-slot 302 b. The traffic channel carries information of user data, i.e., non-overhead data. The total transmit power of the forward channel is fixed and does not change as a function of time.

Typically, the forward link is amplified prior to transmission. The amplifier is capable of providing limited total output power without undesirable distortion of the amplified signal; thus, if more power is transmitted on one channel, less power is available on the other channels. As depicted, the forward link includes a time division multiplexed traffic channel, a pilot channel, and multiple medium access control channels (MACs). Since the forward link is always at a limited total output power (P)_PAM) The MAC, which is transmitted and includes a reverse activation channel (RA), a reverse power control channel (RPC), a DRC lock channel, and an acknowledgement/negative acknowledgement channel (ACK/NAK), is code division multiplexed so that P_PAMIt is necessary to allocate among the RA channel, the RPC channel, the DRC lock channel, and the ACK/NAK channel (ACK/NAK).

The optimal allocation of MAC channel power may ensure that MAC channel power is not a limiting factor in supporting a large number of users and that reverse link capacity may be maximized. Improper or inadequate power allocation may result in errors in power control, which may result in less than optimal capacity. Inadequate or inadequate power allocation has less impact on the RPC channel because it is compensated by closed-loop power control. Conversely, improper or inadequate power allocation to the ACK/NAK channel may result in the packet not being terminated early, which may cause increased interference.

Forward link acknowledgement/negative acknowledgement channel

As discussed, the communication system may require both an old access terminal that supports an access terminal operating the reverse link in accordance with the IS-856 standard and a new access terminal that supports an access terminal operating the reverse link in accordance with the concepts described. To support such operation, each new access terminal transmitting on the reverse link must be provided with information regarding whether the user data transmitted in the subframe has been decoded by the access point. To provide such information and additional channels, an acknowledgement/negative acknowledgement (ACK/NAK) channel is required on the forward link. The ACK/NAK channel may be provided by utilizing in-phase and quadrature branches (branches) of the MAC channel assigned to a given terminal.

Automatic repeat request (ARQ) channel transmission rules

At a given Base Transceiver Station (BTS), the physical layer ARQ is applied to all users in the system, while the MAC layer ARQ is supported only for users with an active cell size equal to 1, where the active cell size is defined as the number of cells in the active set. For each user, the ARQ message from the serving cell BTS is bipolar keyed, i.e., the Acknowledgement (ACK) ═ 1 and the Negative Acknowledgement (NAK) — 1 after the first, second, and third subpackets if sufficient MAC power is present. The non-serving cell BTS transmits ARQ after the first, second and third subpackets using on-off keying (OOK), i.e., ACK +1 and NAK 0. These ARQ are transmitted over three slots. In order to support ARQ at the MAC layer for users who do not perform handover, an ARQ message corresponds to a fourth sub-packet using an OOK scheme in which ACK is 0 and NAK is-1, and the ARQ message is extended to six slots. ARQ extended by three slots (also known as E-ARQ) and conventional non-extended ARQ for the next subpacket are I-Q multiplexed.

A sub-packet is the smallest unit of reverse traffic channel transmission that can be identified by the access network at the physical layer. The subpackets are transmitted in 4 adjacent slots. A subframe is a set of 4 adjacent slots in which an access terminal may transmit a subpacket within 4 slots. At the beginning of the subframe, the CDMA system time in slot T satisfies the equation: (T-frame offset) modulo 4 equals 1. Each physical layer packet should be sent within one or more subpackets, up to 4 subpackets. The interval between the transmission of consecutive subpackets for a single reverse traffic channel physical layer packet should be two subframes or 13.33 milliseconds.

Reverse traffic channel transmissions should use a 4-8-4 slot interlace structure. That is, the transmission slots of a physical layer subpacket (4 slot duration) should be separated by an interval of 8 slot durations within which subpackets of other physical layer packets may be transmitted. If a positive acknowledgement is received on the forward link ARQ channel, the access terminal should terminate transmission of that packet and the next sub-frame offset by that interlace may be used for the first sub-packet of a new physical layer packet transmission. The access terminal will continue transmission of the subpackets of the physical layer packet until it either receives a positive acknowledgement on the forward link ARQ channel or it has sent all 4 subpackets of the physical layer packet within that interlace.

The forward ARQ channel and the forward D-ARQ channel are used by the sectors to send ACKs and NAKs to the access terminals. The forward ARQ channel and the forward D-ARQ channel should be transmitted in 3 consecutive slots.

If the ARQ mode is '0', which is common data of the reverse traffic channel MAC protocol, the sector should transmit the forward ARQ channel after receiving the first, second or third subpacket of the reverse traffic channel packet transmission, use bipolar keying, i.e., +1 ═ ACK, -1 ═ NAK, if the sector is part of the serving cell on the forward channel, and use ACK-directed on-off keying, i.e., +1 ═ ACK, 0 ═ NAK, if the sector is not part of the serving cell on the forward channel.

If the ARQ mode is '1', the sector should transmit the forward ARQ channel after receiving the first, second and third subpackets of the reverse traffic channel packet transmission using ACK-directed on-off keying, i.e., +1 > ACK and 0 > NAK.

The sector should transmit the forward ARQ channel by using NAK-directed on-off keying, i.e., 0 > ACK, -1 > NAK, after receiving the fourth subpacket of a reverse traffic channel packet transmission from an access terminal only when the access terminal's active set size, which is defined as the number of cells in the access terminal's active set, is 1.

If the access terminal's active set size is greater than 1, then the sector should not transmit the forward D-ARQ channel. Otherwise, the sector should transmit the forward D-ARQ channel by using NAK-directed on-off keying, i.e., 0 > ACK, -1 > NAK. For reverse link traffic channel packet transmissions to begin in time slot n-48, the sector should begin transmitting a forward link D-ARQ channel in time slot n.

ARQ messages for reverse traffic channel subpackets transmitted in slots n, n +1, n +2 and n +3 should be transmitted in slots n +8, n +9 and n + 10. D-ARQ messages for reverse traffic channel packets that begin transmission in slot n should be transmitted in slots n +48, n +49, and n + 50.

Forward Link (FL) Medium Access Control (MAC) channel power allocation

As described above, the forward link amplifier is capable of providing a limited total output power (P)_PAM) Without undesirably distorting the amplified signal. As described above, the forward link includes a traffic channel, a pilot channel, and multiple MACs that are time-multiplexed. Because the forward link always has P_PAMTransmitted, and multiple MACs, i.e., a Reverse Activity Bit (RAB) channel, a power control channel (RPC), and an acknowledgement/negative acknowledgement channel (ACK/NAK), are code division multiplexed, so P_PAMThe method comprises the following steps: power (P) allocated to RA channel_RACH) Power allocated to RPC channel (P)_RPCCH) And the power (P) allocated to the ACK/NAK channel_ACK/NAK)。

FIG. 4 is a flow chart illustrating one embodiment of the present invention. Power allocation begins in step 400 and continues in step 402. In step 402, all users within the coverage area of the cell are sorted in order of increasing required MAC channel power. Then, in step 404, the users are placed into different bins based on the required power allocation. If the ARQ powers required for some users are the same, the users are classified in step S406 in order of decreasing forward link signal to interference and noise ratio (FL _ SINR).

If the total allocated available MAC channel power Tarq is less than the total required MAC channel power Tarq _ req for all users, the method proceeds to step 410, which reduces the power allocated to the users in the bin with the highest required ARQ power by a predetermined increment until a predetermined maximum reduction is reached. In an exemplary embodiment, the power allocated to users in the collector with the highest required ARQ power may be reduced by a predetermined increment, for example, by 1dB, up to a maximum limit of, for example, 3 dB. The method then proceeds to step 412.

At step 412, the power allocation to users in each bin whose required ARQ power is arranged in decreasing order is reduced by a predetermined increment until a predetermined maximum reduction is reached for that bin. In an exemplary embodiment, the power allocated to users in a given collector may be reduced by a predetermined increment, such as 1dB, with a maximum reduction of a maximum limit, such as 3 dB. The power allocation of users in each collector, ordered in decreasing order of required power, is reduced until the available ARQ power is allocated to all collectors or until Tarq is greater than or equal to Tarq _ req. If, at step S414, it is determined that Tarq is greater than or equal to Tarq _ req, then the method ends at step 416. Otherwise, steps S410 and 412 are repeated until Tarq is greater than or equal to Tarq _ req.

If Tarq is greater than Tarq _ req after the users are collected (binned) based on the desired power allocation in step 406, then power allocation is initiated for the access terminal based on the sorted list of decreasing FL _ SINR and priority is given to the user with the lowest FL _ SINR in step 420.

If MAC channel power is available after power allocation is initiated for the access terminal based on the sorted list of FL SINR decrements, power allocation is initiated for ARQ channels for all active users in step 424 at a predetermined increment up to a predetermined maximum increment. Active users may include non-server, soft handoff users that do not have the BTS as the serving cell and are not in soft handoff with the BTS. In one embodiment, power allocation is initiated in 1dB increments for all non-server, soft-handoff user's ARQ channels, with a maximum increase of 3 dB. It is then determined whether Tarq is greater than Tarq _ req in step 426. If Tarq is greater than Tarq _ req, then power is consistently initiated for all users in step 428. Otherwise, the method ends at step 430.

In the flow diagrams of fig. 5A-5C, a more detailed embodiment of the processing steps for forward link MAC channel power allocation is shown. As shown in the flowchart of fig. 5A, the power allocation method begins in step 500 and continues in step 502. In step 502, a predetermined percentage, e.g., 6%, of the total MAC channel power is allocated to the RAB channel. The method then continues to step 504.

In step 504, MAC channel power is allocated to the RPC channels of the old and new users. Each user's RPC channel is allocated an amount of power that is no more than a predetermined percentage of the total MAC channel power, e.g., no more than 3% of the total MAC channel power. The MAC channel power is also allocated to the new user's data rate control lock (DRC lock) channel in the same manner, i.e., each new user's DRC lock channel is allocated no more than 3% of the total MAC channel power. The method continues to step 506.

At step 506, a total RPC channel power allocation (Trpc) and a total ARQ channel power allocation (Tarq) are determined. In one embodiment, the maximum power allocation (Max _ RPC _ alloc) for the RPC channel is determined according to the following relationship:

Max_rpc_alloc＝(Prpc，max*Overhead_softhandoff/Margin_rpc)*(#legacy+#new*(PC_Update_rate/600)*Overhead_drclock)

where Prpc, max is the maximum RPC channel power allocation per user, which in one embodiment is 3% of the total MAC channel power,

wherein Overhead _ soft handoff is the soft handoff Overhead, which is the active cell size,

where Margin _ rpc is a power Margin (power Margin), which is a scaling factor that allocates some percentage of the maximum required power,

where, # legacy is the number of legacy users in the cell,

where # new is the number of new users in the cell,

wherein PC _ Update _ rate is a power control Update rate, and

where Overhead _ clock is the DRC lock channel Overhead for the new user.

The total RPC channel power allocation (Trpc) is the lesser of the total required RPC channel power (Trpc _ req) and the Max _ RPC _ alloc. The total ARQ channel power allocation Tarq is given by the following relation:

Tarq＝T-Trpc-Trab

where T is the total MAC channel power, Trpc is the total RPC channel power allocation, and Trab is the RAB channel power allocation.

After the total RPC channel power (Trpc) and the total ARQ channel power (Tarq) are determined in step 506, the method continues to fig. 5B in step 508.

FIG. 5B is a continuation of the flowchart of FIG. 5A, beginning at step 510 and continuing to step 516. Only users that are not in soft handoff are considered at step 516. If it is determined in step 516 that the sector of the base station fails to decode the packet following the fourth subpacket, which is the last subpacket within the packet, then it is determined in step 518 whether the forward link signal to interference and noise ratio (FL SINR) is greater than a predetermined amount, e.g., -2 dB. If there are no non-soft handover users in the cell, the method continues to step 524.

If FL _ SINR > -2dB is determined in step 518, then a predetermined amount of power, e.g., -15dB, is allocated to each E-ARQ channel for non-soft handover users whose decoding of the fourth subpacket failed in step 520. Otherwise, a different amount of power, e.g., -12dB, is allocated to the E-ARQ channel of each non-soft handover user whose decoding of the fourth subpacket failed in step 522. After step 520 or step 522 is completed, the method continues to step 524.

Then, all users that consider a given BTS as a serving cell are considered. The users are ranked for ARQ channel power allocation in the order of FL _ SINR, which in one embodiment may be obtained from Data Rate Control (DRC) information. Users with higher FL _ SINR are ranked higher priority than users with lower FL _ SINR. The method then performs one or more iterations starting at step 524, where the integer M is initially set to 0. The method continues to step 526.

In step 526, ARQ channel power is allocated to the ranked users according to their FL _ SINR. In one embodiment, ARQ channel power is allocated to the ranked users according to the following steps:

A. if FL _ SINR < -2-M (dB), then the user is assigned-12 dB

B. if-2-M (dB) < FL _ SINR < 2-M (dB), then-15 dB is allocated to the user

C. If FL _ SINR > 2-M (dB), then-18 dB is allocated to the user

If it is determined in step 528 that there is not enough MAC channel power available for allocation in any of the above steps A, B or C, then M is incremented by 1 in step 530 and step 526 is repeated until all ranked users are allocated ARQ channel power. After ARQ channel power is allocated to all the ranked users, the method continues to step 532.

In step 532, the system determines if M > 0, i.e., if more than one iteration is necessary to allocate ARQ channel power to all ranked users. If M > 0, then the system sets a flag bit, i.e., ARQ mode, in step 534, and after the ARQ mode flag bit is set, any new users acquired by the intra-sector BTS will be in OOK mode in step 536, even if the BTS is the serving cell for those new users. The method then ends at step 537.

Referring to fig. 5B, if it is determined in step 538 that M-0 lasts at least a predetermined number of adjacent slots T, for example, if the packet length is 16 slots and T is 16 or more, the system may cancel the setting of the ARQ mode flag bit in step 540 and the user acquired by the BTS may be set in the bipolar mode once the BTS sector becomes the serving cell in step 542. The method then continues to fig. 5C at step 544. If M cannot be maintained at a value of 0 for the duration of T consecutive slots in step 538, then any new users acquired by the BTS will be in OOK mode in step 536.

FIG. 5C is a continuation of the flowchart of FIG. 5B, where step 546 represents FIG. 5B, and the flow continues to step 548. In step 548, the system determines whether the MAC channel power is still available when M ═ 0. If the MAC channel power is no longer available when M is 0, the method ends at step 550. Otherwise, the remaining MAC channel power may be allocated to the forward link ARQ channels of the ranked soft-handoff users that do not regard the BTS as the serving cell and that have successfully decoded their packets before the fourth subpacket, which is the last subpacket of each packet, in step 552. In one embodiment, the users are ranked in order of their FL _ SINR. Users with higher FL _ SINR are ranked higher priority than users with lower FL _ SINR. A predetermined amount of power, e.g., -9dB, is allocated to the forward link ARQ channel for each of these users until the available MAC power is exhausted or until all of these users are allocated ARQ channel power.

It is then determined in step 554 whether any remaining MAC channel power is still available. If there is no more MAC channel power available, the method ends in step 556. If MAC channel power is still available, additional power is allocated to the ARQ channel for the non-handoff user that treats the BTS as the serving sector in step 558. The allocation should start with the user with the lowest FL _ SINR to the BTS and move in the direction of increasing FL _ SINR ranking of the users. The allocation should continue until all non-handover users have-12 dB ARQ channel power. If there is still MAC channel power available, the remaining power is used to further optimize the ARQ channels for non-handoff users, such that the ARQ channel for the user with the lowest FL _ SINR is upgraded to-9 dB, and then continues to do so for the user with the next lowest FL _ SINR, and so on. This process should continue until all users in the sector have-9 dB FLARQ power.

After the ARQ channel power is allocated in step 558, it is determined in step 560 whether any MAC channel power is still available. If no more MAC channel power is available, the method ends in step 562. If MAC channel power is still available after step 560 and there are other control channels requiring power in addition to the RPC, DRCLock and ARQ channels, the MAC channel power may be allocated to the other control channels in step 564 and the method then ends in step 566.

AT and AP architecture

An access terminal 600 is illustrated in fig. 6. The forward link signal is received by an antenna 602 and passed to a front end 604 that includes a receiver. Which filters, amplifies, demodulates, and digitizes the signal provided by antenna 602. The digitized signal is provided to a demodulator (DEMOD)606, which demodulator 606 provides demodulated data to a decoder 608. Decoder 608, performs the inverse of the signal processing functions performed at the access terminal and provides decoded user data to a data sink 610. The decoder also communicates with the controller 612 to provide overhead data to the controller 612. The controller 612 further communicates with other functional blocks including the access terminal 600 to provide appropriate control of the operation of the access terminal 600, e.g., data coding, power control. The controller 612 may include, for example, a processor and a storage medium coupled to the processor and containing a set of instructions executable by the processor.

User data to be transmitted to the access terminal is provided by a data source 614 and is transmitted to an encoder 616 as directed by the controller 612. The encoder 616 is further provided overhead data by the controller 612. An encoder 616 encodes the data and provides the encoded data to a Modulator (MOD) 618. The data processing in encoder 616 and modulator 618 is performed in accordance with the reverse link generation procedure described in the above documents and figures. The processed data is then provided to a transmitter within the front end 604. The transmitter modulates, filters, amplifies, and transmits the reverse link signal over the air via antenna 602.

Fig. 7 illustrates a controller 700 and an access terminal 702. User data generated by the data source 704 is provided to the controller 700 via an interface unit, e.g. a packet network interface PSTN (not shown). As depicted, the controller 700 is coupled to a plurality of access terminals that form an access network. (only one access terminal 702 is shown in fig. 7 for simplicity). The user data is provided to a plurality of selector elements (only one selector element 702 is shown in fig. 7 for simplicity). A selector element 708 is assigned to control the exchange of user data between the data source 704 and the data sink 706 and between one and more base stations under the control of the call control processor 701. The call control processor 710 may include, for example, a processor and a storage medium coupled to the processor and containing a set of processor-executable instructions. As shown in fig. 7, the selector element 702 provides user data to a data queue 714, the data queue 714 containing user data to be transmitted to access terminals (not shown) served by the access terminal 702. User data is provided to the channel element 712 by a data queue 714, as controlled by a scheduler 716. The channel element processes the user data in accordance with the IS-856 standard and provides the processed data to transmitter 718. Data is transmitted on the forward link through antenna 722.

Reverse link signals from an access terminal (not shown) are received at antenna 724 and provided to a receiver 720. Receiver 720 filters, amplifies, demodulates, and digitizes the signal and provides the digitized signal to channel element 712. The channel element performs the inverse of the signal processing functions done at the access point and provides decoded data to the selector element 708. Selector element 708 passes the user data to a data sink 706 and overhead data to a call control processor 710.

Those skilled in the art will appreciate that, although the flowcharts are depicted in sequential order for ease of understanding, certain steps may be performed in parallel in an actual implementation.

Those of skill in the art would understand that information and signals may be represented using any of a variety of different technologies and techniques. For example, data, instructions, commands, information, signals, bits, symbols, and chips that may be referenced throughout the above description may be represented by voltages, currents, electromagnetic waves, magnetic fields or particles, optical fields or particles, or any combination thereof.

Those of skill would further appreciate that the various illustrative logical blocks, modules, circuits, and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both. To clearly illustrate this interchangeability of hardware and software, various illustrative components, blocks, modules, circuits, and steps have been described above generally in terms of their functionality. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention.

The various illustrative logical blocks, modules, and circuits described in connection with the embodiments disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration.

The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other storage medium known in the art. An exemplary storage medium is coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. The processor and the storage medium may reside in an ASIC. The ASIC may reside in a user terminal. In the alternative, the processor and the storage medium may reside as discrete components in a user terminal.

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

A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document or the patent disclosure, as it appears in the patent and trademark office patent file or records, but otherwise reserves all copyright rights whatsoever.

Claims (13)

1. A method of allocating power to a remote station specific control channel, the method comprising:

A) sorting the plurality of access terminals into a plurality of bins in an order of increasing required medium access control, MAC, channel power;

B) classifying access terminals requiring equal MAC channel power in order of decreasing forward link signal to interference and noise ratio, FL _ SINR, if the MAC channel power required by two or more access terminals is equal;

C) determining a total available automatic repeat request, ARQ, power based on the total MAC channel power, a total power allocated to a reverse power control, RPC, channel, and a total power allocated to a reverse activity bit, RAB, channel;

D) comparing the total available ARQ power to a total required ARQ power for the access terminal; and

E) if, according to step D), the total available ARQ power is less than the total required ARQ power for the access terminal,

a) reducing power allocated to users in one of a plurality of bins in which the required ARQ power is greatest by a predetermined increment until a predetermined maximum reduction is reached;

b) decreasing the power allocated to users in each of the remaining bins in decreasing order of required ARQ power by the predetermined increment until a predetermined maximum decrease is reached;

c) if the total available ARQ power is less than the total required ARQ power, repeating steps a) and b) until the total available ARQ power is greater than or equal to the total required ARQ power.

2. The method of claim 1, wherein the step of determining the total available ARQ power comprises subtracting the total power allocated to RPC channels and the total power allocated to RAB channels from the total MAC channel power.

3. The method of claim 1, further comprising:

F) if, according to step D), the total available ARQ power is greater than the total required ARQ power for the access terminal,

a) starting power allocation to the remaining access terminals in the descending order of the FL _ SINR; and is

b) Power allocation for ARQ channels for all active access terminals is initiated in predetermined increments until a predetermined maximum increase is reached.

4. The method of claim 1, wherein the step of determining a total available ARQ power comprises:

allocating a first predetermined fraction of the total MAC channel power to the RAB channels within a cell; and

allocating power to the RPC channels within the cell that is not greater than a second predetermined fraction of the total MAC channel power.

5. The method of claim 4, further comprising:

calculating the total required ARQ power for all access terminals in the cell;

determining whether the access terminal includes one or more non-handover access terminals that fail to decode a packet following a last subpacket of the packet;

if the access terminal includes one or more non-handover access terminals that fail to decode a packet following the last subpacket, determining whether a forward link signal-to-interference-and-noise ratio, FL _ SINR, of each non-handover access terminal that fails to decode a packet following the last subpacket is greater than a predetermined threshold;

allocating a first predetermined power level to an extended automatic repeat request, E-ARQ, channel for each of the non-handover access terminals if the FL _ SINR is greater than the predetermined threshold, wherein the non-handover access terminals fail to decode packets following the last subpacket and have FL _ SINR greater than a predetermined threshold; and

otherwise, a second predetermined power level is allocated to the E-ARQ channel.

6. The method of claim 4, further comprising allocating a remaining MAC channel power to all ARQ channels for access terminals that regard the cell as a serving cell, the remaining MAC channel power being obtained after subtracting the total power allocated to RPC channels and the total power allocated to RAB channels from the total MAC channel power.

7. The method of claim 6, wherein the step of allocating the remaining MAC channel power to ARQ channels of all access terminals regarding the cell as a serving cell comprises:

ranking all access terminals in order according to the FL _ SINR of each of the access terminals;

initially setting the number M to 0;

allocating ARQ channel power to an access terminal designated from a plurality of access terminals regarding the cell as a serving cell, according to the following steps:

a) assigning a first predetermined ARQ channel power level to the designated access terminal if FL _ SINR < -x-M, where x is a predetermined number;

b) assigning a second predetermined ARQ channel power level to the designated access terminal if-x-M < FL _ SINR < x-M; and

c) assigning a third predetermined ARQ channel power level to the designated access terminal if FL _ SINR > x-M; and is

If the remaining MAC channel power is exhausted, then adding 1 to M; and is

Repeating steps a) -c) until the remaining MAC channel power is allocated to ARQ channels for all access terminals regarding the cell as a serving cell.

8. The method of claim 7, further comprising:

determining whether M is greater than 0 after all access terminals regarding the cell as a serving cell are assigned ARQ channel power;

if M is greater than 0, then

Setting an ARQ mode flag bit; and is

And setting one or more obtained new access terminals of the cell in an on-off keying (OOK) mode.

9. The method of claim 8, further comprising:

determining whether M is equal to 0 over a predetermined number of consecutive time slots;

if M is equal to 0 in a predetermined number of consecutive time slots

Canceling the setting of the ARQ mode flag bit; and is

One or more new access terminals obtained by the cell are set in a bipolar mode.

10. The method of claim 9, further comprising:

determining whether a remaining MAC channel power is available after all ARQ channels of an access terminal regarding the cell as a serving cell are allocated to the MAC channel power and M is equal to 0; and

if remaining MAC channel power is available after all ARQ channels for access terminals regarding the cell as a serving cell are allocated to MAC channel power and M equals 0

Allocating the remaining MAC channel power to ARQ channels of one or more soft-handoff access terminals that do not regard the cell as a serving cell and have successfully decoded a packet preceding a last subpacket of the packet.

11. The method of claim 10, further comprising ranking the soft-handoff access terminals in order according to the FL _ SINR for each of the soft-handoff access terminals that do not regard the cell as a serving cell and have successfully decoded a packet before the last subpacket.

12. The method of claim 11, wherein a predetermined power level is allocated to the ARQ channel of a soft handover access terminal that does not regard the cell as the serving cell and has successfully decoded a packet before the last subpacket according to the ranking until the ARQ channel of the soft handover access terminal that does not regard the cell as the serving cell and has successfully decoded a packet before the last subpacket

The ARQ channels of all soft-handoff access terminals that do not regard the cell as the serving cell and have successfully decoded the packet before the last subpacket, are allocated until MAC channel power,

or there is no more remaining MAC channel power.

13. The method of claim 12, further comprising:

determining whether remaining MAC channel power is available after the ARQ channels of all soft-handoff access terminals that do not regard the cell as a serving cell and have successfully decoded a packet preceding the last subpacket are assigned MAC channel power; and

allocating the remaining MAC channel power to ARQ channels of one or more non-handover access terminals if the remaining MAC channel power is available after the ARQ channels of all access terminals that do not regard the cell as a serving cell and have successfully decoded a packet before the last subpacket are allocated to MAC channel power.