ES2534828T3 - Procedure and apparatus for notifying information in a wireless communications system - Google Patents

Abstract

An apparatus (120) for notifying in a wireless communication system, comprising: means for generating a set of notifications for each of a plurality of notification intervals; means for arranging the set of notifications for each notification interval according to a notification format; means for repetitively sending a plurality of notification sets in the plurality of notification intervals; means for receiving an assignment of a control channel used to send notifications; and means for determining the notification format based on the control channel assignment.

Description

Procedure and apparatus for notifying information in a wireless communications system

5 Background

The present disclosure relates generally to communications and, more specifically, to techniques for reporting information in a wireless communications system.

10 A multiple-access wireless communications system can concurrently support communications for multiple terminals on the downlink and uplink. The downlink (or direct link) refers to the communication link from the base stations to the terminals, and the uplink (or reverse link) refers to the communication link from the terminals to the base stations.

15 The terminals can be located throughout the system and can observe different channel conditions. In addition, these terminals may have different requirements and / or data capabilities. The terminals can notify various types of information in order to obtain adequate service from the system and ensure proper operation of the system. For example, a terminal may estimate the downlink channel quality for a base station and may send a channel quality notification to the base station through the uplink.

20 The base station may use the channel quality notification to allocate radio resources to the terminal and / or to select an appropriate data transmission rate to the terminal through the downlink.

The information notified by the terminals, despite being relevant or important, supposes an overload in the system. Therefore, it is desirable to send the information in the most efficient way possible so that a greater number of resources

25 available radio can be used to send data.

A system and a method for sending measurement notifications are known from WO 2004/100450 A1. To avoid protocol ambiguities such that a station requesting a notification depends on a different reference beacon compared to a station receiving the notification, a

30 mechanism for time stamp notifications. The measurement notification includes several fields, in which a field is a measurement notification and a field is a time stamp.

WO 2004/084503 A2 of the prior art refers to a wireless communications network. To address the problem that packet switching traffic suddenly increases and that the mechanisms

The planning techniques used by conventional base stations fail to effectively load the reverse wireless link, this prior art teaches to communicate the buffer status of the mobile station to the base station and also to communicate information in relation to the data transmission rate used. by the mobile station.

From the patent application WO 2005/060132 A1 a method and an apparatus for requesting and

40 notify channel quality information in a mobile communication system. To provide channel quality information quickly and efficiently, this prior art suggests allocating a dedicated feedback channel to notify the channel quality. A reply message sent in response to a request message requesting channel quality information is sent in a notification format included in the request message.

45 Therefore, there is a need in the art for techniques to report information effectively in a wireless communications system.

Summary

The invention is defined in the independent claims. Particular embodiments are set forth in the dependent claims.

This document describes techniques for sending notifications effectively in a wireless communications system. Notifications can contain various types of information, such as the quality of

55 channel, a request for radio resources, available transmission power, interference, accumulated delay information, sector information, etc.

In one example, notifications are sent repetitively according to a notification format. A terminal receives an assignment from a control channel used to send notifications and determines a notification format to be used based on the assignment. For example, one notification format can be used for a complete (for example, full tone) assignment of the control channel, and another notification format can be used for an assignment

partial (for example, split tone). A notification format indicates a specific sequence of notifications sent in specific locations of a control channel frame. A notification format may also have other characteristics, as described below. The terminal generates a set of notifications for each notification interval and arranges the set of notifications according to the notification format. The terminal sends from

5 repetitively a plurality of notification sets in a plurality of notification intervals using the notification format.

In another example, notifications are sent adaptively based on operating conditions. A terminal sends notifications according to a first notification format to a base station. The first notification format may be a default notification format or may be selected based on the current operating conditions of the terminal. The operating conditions can be characterized by the environment (for example, mobility) of the terminal, the capabilities of the terminal, the quality of service (QoS) of traffic for the terminal, etc. Changes in operating conditions are detected. Then, a second notification format is selected based on the changes detected in the operating conditions. Then the terminal sends

15 notifications according to the second notification format. An appropriate notification format can be selected for use when changes in operating conditions are detected.

Various aspects and embodiments of the invention will be described later in greater detail.

20 Brief description of the drawings

Aspects of embodiments of the invention will become more apparent from the detailed description set forth below when taken together with the drawings, in which similar reference characters identify similar parts.

25 FIG. 1 shows a wireless communications system.

FIG. 2 shows an example signal structure.

30 FIG. 3 shows an exemplary structure of a dedicated control channel (DCCH).

FIG. 4 shows example assignments of the DCCH.

FIG. 5 shows a notification transmission scheme for the DCCH. 35 FIG. 6 shows a notification format for a full DCCH tone assignment.

FIG. 7 shows another notification format for full tone assignment.

40 FIG. 8 shows a notification format for a three-way split tone assignment.

FIG. 9 shows a notification transmission scheme for a control channel.

FIG. 10 shows a notification transmission scheme with selectable notification formats. 45 FIG. 11 shows a process for sending notifications repetitively.

FIG. 12 shows a device for sending notifications repetitively.

50 FIG. 13 shows a process for sending notifications according to operating conditions.

FIG. 14 shows a device for sending notifications according to operating conditions.

FIG. 15 shows a block diagram of a base station and a terminal. 55

Detailed description

The expression "by way of example" is used herein with the meaning of "serving as an example, instance or illustration". Any embodiment or design described herein as "by way of example" 60 should not necessarily be considered preferred or advantageous with respect to other embodiments or designs.

FIG. 1 shows a wireless communication system 100 with multiple base stations 110 and multiple terminals 120. A base station is a station that communicates with the terminals. A base station may also be referred to as, and may contain part or all of the functionality of, a node B, an access point and / or some other network entity. Each base station 110 provides communication coverage for a particular geographic area 102. The term "cell" may refer to a base station and / or its coverage area, depending on the context in which the term is used. To improve system capacity, a base station coverage area can be divided into multiple smaller areas, for example, into three smaller areas 104a, 104b and 104c. Each smaller area can receive service from a respective base station sector (BSS), which can also be called a base transceiver subsystem (BTS). The term "sector" may refer to a BSS and / or its coverage area, depending on the context in which the term is used. In a sectorized cell, the BSS for all sectors of that cell are normally located in the same position within the base station for the cell. The notification techniques described herein can be used in systems with sectorized cells, as well as in systems with non-sectorized cells. In the following description, the term "base station" generally refers to a station that serves a cell, as well as a station that serves a sector.

In a centralized architecture, a system controller 130 is coupled to base stations 110 and provides coordination and control for those base stations. The system controller 130 may be a single network entity or a collection of network entities. In a distributed architecture, the base stations can communicate with each other as necessary.

Terminals 120 may be dispersed throughout the system, and each terminal may be stationary or mobile. A terminal may also be referred to as, and may contain some or all of the functionality of, a wireless terminal (WT), an access terminal (AT), a mobile station (MS), a user equipment (UE), a station of subscriber and / or some other entity. A terminal can be a wireless device, a cell phone, a personal digital assistant (PDA), a wireless modem, a manual device, etc. A terminal can communicate with a

or more base stations through transmissions on the downlink and uplink. In the following description, the terms "terminal" and "user" are used interchangeably.

The notification techniques described herein can be used in various wireless communication systems. These techniques can also be used in various radio technologies and multiple multiple access schemes, such as multiple code division access (CDMA), multiple time division access (TDMA), multiple frequency division access (FDMA), FDMA orthogonal (OFDMA), Flash-OFDM® and single carrier FDMA (SC-FDMA). OFDMA and SC-FDMA divide a frequency band (for example, the system bandwidth) into multiple orthogonal tones, also referred to as subcarriers, subbands, bins, etc. Each tone can be modulated with data. In general, modulation symbols are sent in the frequency domain with OFDMA and in the time domain with SC-FDMA. The techniques can also be used in wireless communication systems that use a combination of multiple access schemes, for example OFDMA and CDMA.

For clarity, certain aspects of the notification techniques are described below for an example OFDMA system. In general, the OFDMA system can use any tone structure with any number of total tones and any number of usable tones. In an exemplary embodiment, the OFDMA system uses a tone structure with 128 total tones and 113 usable tones. An OFDM symbol can be generated in a manner known in the art and sent in an OFDM symbol period (or simply, a symbol period).

The notification techniques described herein can be used with various signal structures. A signal structure indicates the way in which data and signals are sent. For clarity, an example signal structure is described below.

FIG. 2 shows an embodiment of a signal structure 200. The timeline for the transmission is divided into superultraranuras. Each superultraranura has a predetermined length of time (for example, approximately 13.1 seconds) and includes eight ultraranges with indices from 0 to 7. Each ultraranura includes 18 beacon slots with indices from 0 to 17, and each beacon groove includes eight super slots with indexes from 0 to 7. For the downlink, each super slot includes a header (H) followed by eight slots with indexes from 0 to 7. The super slot header covers two symbol periods, each slot covers 14 symbol periods and each super slot covers 114 symbol periods. For the uplink, each super slot includes an uplink access channel (UL.ACH) followed by 15 programmed intervals with indices from 0 to 14. The UL.ACH covers 9 symbol periods, each programmed interval covers 7 symbol periods and each super slot covers 114 symbol periods.

FIG. 2 shows a specific signal structure. Various other signal structures can also be used, and this is within the scope of the present invention. For clarity, notification techniques are described below for the signal structure shown in FIG. 2.

In one embodiment, a terminal is assigned segments of a dedicated control channel (DCCH) after switching to an ACTIVE state of a connection to a base station. A connection can be considered as a collection of channels established between the terminal and the base station for the physical layer (PHY) and / or the media access control layer (MAC). The terminal can receive data on the downlink and / or transmit data on the uplink during the ACTIVE state. The terminal uses the assigned DCCH segments to send notifications on the uplink to the base station. These notifications can be for various types of information, as described later.

The DCCH can be implemented in several ways. In one embodiment, the DCCH comprises a set of logical tones (for example, 31 logical tones), also called DCCH tones. Each DCCH tone can be mapped with a specific usable / physical tone at each programmed interval and can jump from physical tone to physical tone at different programmed intervals according to a tone jump operation.

FIG. 3 shows an embodiment of a DCCH 300 structure. In this embodiment, 40 DCCH segments with indices from 0 to 39 are defined for each DCCH tone in each beacon groove. A beacon slot includes 64 slots or, equivalently, 128 half slots with indexes from 0 to 127. Each DCCH segment uses a tone and encompasses three half slots. Five DCCH segments are formed with the last 15 half slots of each super slot, where the first half slot is used for the UL.ACH. Therefore, the DCCH segments 0 to 4 are formed with the half grooves 1 to 15 in super slot 0, the DCCH segments 5 to 9 are formed with the half grooves 17 to 31 in the super slot 1 (not shown in FIG. 3 ), etc., and the DCCH segments 35 to 39 are formed with the half slots 125 to 127 in the super slot 7.

In the embodiment shown in FIG. 3, µ31 logical tones are used for the DCCH, 40 DCCH segments are defined for each DCCH tone in each beacon slot and a total of 1240 DCCH segments are available in each beacon slot. The available DCCH segments can be assigned to a terminal in several ways.

FIG. 4 shows an exemplary allocation scheme for the DCCH structure shown in FIG. 3. In one embodiment, each DCCH tone can be assigned to one or multiple users. Multiple DCCH modes can be defined. Each DCCH mode can correspond to a specific number of users that have a given DCCH tone assigned. In a full DCCH mode, also called full tone format / assignment, a DCCH tone is assigned to a user, who can send notifications on all DCCH segments in that tone. In a DCCH media mode, also called bidirectional split tone format / assignment, a DCCH tone is assigned to two users. In a one-third mode of DCCH, also called three-way split tone format / assignment, a DCCH tone is assigned to three users. In a DCCH quarter mode, also called four-way split tone format / assignment, a DCCH tone is assigned to four users. Other DCCH modes can also be defined. For a N-way split tone assignment, where N> 1, N users can send notifications in a time-division multiplexed (TDM) manner in the DCCH segments of a DCCH tone. The DCCH segments can be assigned to the N users, repeatedly cycling through these users, and assigning a DCCH segment to each user in each cycle. Each user is then assigned DCCH segments that are evenly distributed over time, as shown in FIG. 4. In all assignments, each user can send notifications in the DCCH segments assigned to that user.

FIG. 3 and 4 show specific embodiments of a structure and an allocation scheme for the DCCH. These embodiments provide frequency diversity through frequency hops and time diversity by assigning time-distributed DCCH segments. DCCH can also be implemented in other ways and can be divided and assigned to users in other ways. For example, the DCCH can be implemented with specific tones at specific symbol periods. As another example, users can be assigned multiple DCCH segments in a given time interval. For clarity, much of the following description is for the embodiments shown in FIG. 3 and 4.

FIG. 5 shows an embodiment of a notification transmission scheme 500 for the DCCH. In this embodiment, a terminal sends a set of notifications in the DCCH to a base station at each notification interval of a beacon slot. Each set of notifications is sent using a notification format that is either known a priori or can be determined by both the terminal and the base station.

In general, a notification format is a structure for sending one or more notifications. A format of 5

Notification may contain several parameters, such as the types of notification that are sent, the rate at which each type of notification is sent, the location and length of each notification and / or other information. A notification format can also be called a notification structure, control channel format, DCCH format, etc. Notifications can be sent effectively using a notification format since

5 Generally, supplementary information (for example, headers) is not necessary to convey the type of notification, location, size and format of each notification sent using the notification format. All or much of the supplementary information is implicit in the notification format. Therefore, notifications may contain only, or for the most part, useful information and little, or none, supplementary information.

10 As shown in FIG. 5, notifications can be sent periodically using the same notification format for each notification interval, which is a beacon slot in FIG. 5. The same set of notifications will then be sent at each notification interval. However, the values in the notifications can change from one set of notifications to another set of notifications depending on the measurement results and / or the conditions at different notification intervals. The interpretation of notifications in

15 each set is fixed and is determined by the notification format.

A terminal can send several types of notification. Table 1 lists some types of notification and provides a brief description of each type of notification.

20 Table 1

Type of Notification

Description

SNR DL

Contains the signal to noise ratio (SNR) or the downlink channel quality for a base station measured at the terminal.

UL request

Contains accumulated delay information for the terminal.

Delay information

It contains the delay experienced by data to be sent by the terminal.

DCCH power reduction

It contains the transmission power available in the terminal.

Beacon Rate

Contains interference information.

Own noise SNR

It contains the highest SNR that can be achieved in the terminal.

Sector Limit

It contains information about whether the terminal is in the limit of two sectors, and if so, what sector limit.

The SNR DL denotes the channel quality or the received downlink SNR observed in the terminal for a base station. The terminal can receive transmissions on the downlink from one or multiple base stations. The terminal can measure the SNR DL of each base station based on a downlink pilot channel (DL.PICH) sent by that base station. The terminal can generate full and delta SNR DL notifications for each base station. A full SNR DL notification provides the SNR DL measured in the current notification interval. A delta SNR DL notification offers a delta SNR, which is the difference between the SNR DL in the current notification interval and the SNR DL in a previous notification interval. SNR delta

30 is also called relative SNR or differential SNR. If the terminal can receive downlink transmissions from multiple base stations, then a full SNR DL notification for a base station can also indicate whether that base station is preferred or not.

The own noise SNR is the saturation level of the DL SNR and is the SNR that a receiver in the terminal

35 would observe for a received signal if the base station transmits the signal at infinite power. The saturation level of the SNR DL is determined by the terminal receiver's own noise, which may be due to channel estimation errors and / or other factors. The terminal can determine the saturation level of the SNR DL as follows. The terminal may assume that if a base station transmits at a power P, then the SNR DL can be obtained as:

where G represents the path gain of the wireless channel from the base station to the terminal. The quantities of equation (1) are provided in linear units.

The term G · P represents the signal strength received at the terminal. The term N represents the power of

interference received The term a0 · G · P represents its own noise, so that a higher value of a0 denotes a higher value of its own noise. The terminal can measure the received power of a null downlink channel (DL.NCH) to determine the interference power N. The terminal can also measure the received power (denoted as G · P0) and the SNR (denoted as SNR0) from DL.PICH. The saturation level of the SNR DL is equal to 1 / a0 and can be calculated as follows:

The quantities of equation (2) are provided in linear units.

10 The UL request contains accumulated delay information in the terminal. The terminal can maintain one or more (for example, up to four) MAC frame queues. Each MAC frame queue can store MAC frames for a group of requests. MAC frames can be generated from higher layer protocol packets. Each package can be mapped with a group of requests, and all MAC frames generated for that package

15 can be placed in the associated MAC frame queue. The UL request can contain the number of MAC frames in the (for example, four) groups of requests that the terminal can transmit, representing the accumulated delay information for the terminal. The base station may assign traffic channel segments (or radio resources) to the terminal based on accumulated delay information, channel conditions and / or other factors, such as the priority of the data to be sent by the terminal.

20 The delay information contains the amount of delay experienced by the data to be sent by the terminal. The terminal can track the delay experienced by MAC frames in each request group. For example, the terminal may maintain D [k], which indicates the current line head delay experienced by the oldest MAC frames of the request group k, for k = 0,…, 3. The information of

The delay can then comprise the delays, or D [k], of the MAC frames in the request groups. The base station may take into account the delay information when assigning traffic channel segments to the terminal.

The DCCH power reduction contains the amount of transmission power available in the terminal for the

30 uplink data transmission. The terminal can adjust the transmission power of the DCCH to achieve an objective level of performance for notifications sent on the DCCH. The terminal has a certain maximum transmission power, which may depend on the design of the terminal. The DCCH power reduction is the difference between maximum transmission power and DCCH transmission power, and can be obtained as follows:

where

40 PowerTxDCCHULwt is the tone transmit power of UL.DCCH,

Maximum Power wt is the maximum transmission power of the terminal, and

Power Reduction DCCHULwt is the DCCH power reduction.

45 All amounts in equation (3) are provided in units of dBm. The DCCH power reduction can be used to assign an appropriate number of tones and / or to select a suitable data transmission rate on the uplink.

50 The beacon rate expresses interference, possibly produced by the terminal to different base stations, and can be used for the management of uplink interference. The terminal can measure the channel gain (or signal strength) of neighboring base stations with respect to the channel gain of a service base station. The terminal can measure the power received from the beacon (PB0) and the power received from the pilot channel (PP0) of the service base station. The terminal can similarly measure the power received from the beacon

55 (PBi) and the power received from the pilot channel (PPi) of each neighboring base station i. The terminal can then calculate a Gi channel gain ratio for the base station i as follows:

where K is the ratio of the beacon transmission power to the pilot channel's transmission power, and Z0 is a scaling factor that depends on how the tones are used at the service base station.

A generic beacon rate (BNR) notification can be generated based on the channel gain ratios of neighboring base stations, as follows:

where 15 b0 is an uplink load factor broadcast by the service base station, and

bi is an uplink load factor broadcast by the neighboring base station i.

20 The quantities of equations (5) and (6) are provided in linear units. The uplink load factor bi indicates the load observed by the base station i on the uplink for all terminals receiving service from the base station i. The uplink load factor is then used to indicate the amount of traffic load observed by the base station i. Base stations can exchange or disseminate their load factors to control uplink interference and increase overall performance.

25 The terminal can calculate generic beacon rate notifications using equation (5) in beacon grooves with even indexes and using equation (6) in beacon grooves with odd indices. The generic beacon rate notifications provide the cost of interference with respect to all neighboring base stations (with equation (5)) or the nearest neighboring base station (with equation (6)), if the terminal were to transmit to

30 service base station.

A special beacon rate notification can be generated for the neighboring base station k, as follows:

The special beacon rate notification provides the cost of interference with respect to a specific base station k, if the terminal were to be transmitted to the service base station.

40 The sector boundary provides information about whether the terminal is located at the boundary of two adjacent sectors of the same base station, and if so, what sector boundary. The sector limit information can be used by the base station to coordinate the planning of the traffic channels in the two sectors to better service the terminal when the terminal is in the sector limit. For example, the base station can reduce the transmission power in a sector, so that the terminal will experience less interference from that sector.

45 Table 1 offers some types of notification that can be sent by the terminal to support efficient data transmission and proper system operation. Fewer types, different types and / or additional types of notification may also be sent, and this is within the scope of the present invention.

50 FIG. 6 shows an embodiment of a notification format 600 that can be used by a terminal with a

full tone assignment for the DCCH. The notification format 600 covers a DCCH frame of 40 DCCH segments and can be sent in 8 super-slots of a beacon slot. A DCCH frame is a unit of the DCCH used to send a set of notifications according to a notification format. The notification format 600 has six bits of information in each DCCH segment. Notifications sent in each

5 DCCH segment of notification format 600 are shown in FIG. 6. In particular, a 5-bit SNR DL notification and a 1-bit UL request are sent in the DCCH 0 segment, a 2-bit mode indicator and a 4-bit notification are sent in the DCCH 1 segment, a notification 3-bit delta SNR DL and a 3-bit UL request are sent in the DCCH 2 segment, etc.

10 Table 2 lists the different types of notification included in notification format 600 and the number of notifications of each type. In notification format 600, field D can be configured to send a notification of one of four possible types, which is indicated in field C. Field D is configurable and offers flexibility when sending notifications at the expense of certain information. supplementary to field C.

15 Table 2

Type of notification / Field

Size (bits) Description Format 600. Number of notifications Format 700. Number of notifications

TO

5 5 bit full SNR DL notification 12 8

B

3 3 bit delta delta SNR notification 12 8

C

2 Indicates the notification that is being sent in field D: 00: 4-bit UL request 01: 4-bit own noise SNR notification 10: 4-bit sector information 11: 4-bit delay information 4 8

D

4 Variable notification type signaled in field C 4 8

AND

4 4-bit UL request 8 to 12 8 to 16

F

3 3-bit UL request 12 8

G

one 1-bit UL request 16 16

H

5 5-bit DCCH power reduction notification 2 4

I

4 4-bit beacon rate notification one 2

J

4 4-bit own noise SNR notification 1 to 5 2 to 10

K

4 4-bit delay information 0 to 4 0 to 10

L

4 4-bit sector information 0 to 4 0 to 10

M

1 or 2 Reserved 10 12

FIG. 7 shows an embodiment of a notification format 700 that can also be used by a terminal with a full tone assignment for the DCCH. The notification format 700 covers a DCCH frame of 40 20 DCCH segments and has six bits of information in each DCCH segment. Notifications sent in each DCCH segment of notification format 700 are shown in FIG. 7. Notification format 700 can be used for a channel that varies more slowly. Therefore, full and delta SNR DL notifications are sent less frequently in notification format 700 than in notification format 600, as indicated in the last two columns of Table 2. The bits saved when fewer SNR notifications are sent DL are used for more

25 configurable D fields.

FIG. 8 shows an embodiment of a notification format 800 that can be used by a terminal with a three-way split tone assignment for the DCCH. Notification format 800 covers a DCCH frame of 40 DCCH segments and has eight bits of information in each DCCH segment. However, only 13 segments

30 DCCHs are assigned to the terminal, another 26 DCCH segments are assigned to other terminals and the last DCCH segment is reserved (Rsvd). Notifications sent in each assigned DCCH segment of notification format 800 are shown in FIG. 8. Notifications are generally sent less frequently as there are fewer DCCH segments available in the 800 notification format.

In one embodiment, the terminal sends notifications according to a notification format at each notification interval after receiving an assignment from DCCH. In another embodiment, the terminal sends a special set of notifications in the first super slot after receiving the DCCH assignment and then sends notifications using the notification format. The special set of notifications may include, for example, a 4-bit UL request, a 5-bit SNR DL notification, an own noise SNR notification, a beacon rate notification, a DCCH power reduction notification, etc. Therefore, the terminal can quickly provide all relevant information to the base station in the special set of notifications.

In the embodiments shown in FIG. 6 and 7, six bits of information can be sent in each DCCH segment. In the embodiment shown in FIG. 8, eight bits of information can be sent in each DCCH segment. Each DCCH segment may comprise a fixed number of tone symbols, for example 21 tone symbols. A symbol-tone is a tone in a symbol period and can be used to send a modulation symbol. For a given number of tone symbols, more bits of information can be sent using a coding and modulation scheme that has less redundancy and therefore less reliability.

FIG. 6 to 8 show specific embodiments of three notification formats, each presenting a specific sequence of notifications that is arranged in a specific order. Other different notification formats can also be defined.

In one embodiment, for a given DCCH assignment (for example, a full tone assignment or a three-way split tone assignment), different notification formats are defined for different operating conditions. The operating conditions of a terminal can be characterized by several factors, such as the environment of the terminal, the capabilities of the terminal, the QoS of the traffic to be sent through the terminal, the way the system works, etc. These factors can determine the type of notification to be sent, the rate of delivery of each type of notification and the information to be included in each notification.

The terminal environment can be characterized by several factors, such as the mobility of the terminal (for example, low or high mobility), the channel conditions (for example, high or low SRN), etc. A notification format for low mobility (for example, stationary or low speed) can send SNR notifications less frequently than a notification format for high mobility (for example, high speed). An SNR notification for low mobility channel conditions may have more bits than an SNR notification for high mobility channel conditions. The reason is that the SNR under high mobility channel conditions tends to vary. Given the association of loop latency with SNR measurement and notification, it may not be necessary to notify the SNR very accurately. A notification format with more notifications and / or more bits for certain notifications can be used for good channel conditions, since the base station can reliably receive notifications with less coding redundancy.

The capabilities of the terminal can indicate whether the terminal supports one or multiple frequency channels (or tone blocks). The capabilities can also indicate whether the terminal supports single-input and single-output (SISO), single-input and multi-output (SIMO), multi-input and single-output (MISO) and / or multi-input and multi-output ( MIMO), which may have different notification requirements. A single data stream can be sent on a single space channel with SISO, SIMO and MISO. Multiple data streams can be sent simultaneously on multiple spatial channels with MIMO. A notification format for SISO, SIMO and MISO can send a single SNR value for a space channel in an SNR notification. A notification format for MIMO can send either multiple SNR values for multiple space channels in an SNR notification or multiple SNR notifications with a single SNR value for a space channel.

Traffic QoS may influence the notification. Different types of traffic (for example, voice, video, packet data, etc.) may have different QoS. The QoS can be quantified by delay tolerance, maximum data transmission speed, average data transmission speed, distribution option and / or other criteria. For example, voice may be associated with a requirement of short delay, a fixed data rate and better effort distribution due to the time-sensitive nature of the voice. Packet data can be associated with a higher delay requirement, a high maximum data rate and a guaranteed distribution. A notification format may include more UL requests and / or UL requests with more details when there are different traffic QoS.

The way the system works can also influence the notification. For example, the system may use time division duplexing (TDD) or frequency division duplexing (FDD). In a TDD system, the downlink and the uplink share the same frequency band, and it can be assumed that the downlink channel is reciprocal to the uplink channel. In this case, a base station can estimate the downlink channel conditions (for example, the gains and / or the SNR of the DL channel)

based on an uplink transmission (eg pilot signal) from the terminal. In an FDD system, the downlink and uplink use different frequency bands, and the downlink channel cannot correlate well with the uplink channel. In this case, the terminal can estimate the downlink channel conditions and send notifications to the base station. Different notification formats can be used in TDD and FDD systems.

In general, a notification format may comprise any combination of notification types, any number of notifications of each type and any provision of notifications. The number of notifications of each type can be selected based on the capacity of the control channel assignment used to send the notification, the importance or criticality of that type of notification with respect to other types of notification, how quickly the information of that type of notification (which may depend on the environment), and / or other factors. Each notification can have any size and can have any format / structure. Notifications can be arranged so that each notification is sent completely in a transmission, for example, in a DCCH segment as shown in FIG. 6 to 8, which can improve the use of these notifications. A notification can also be sent on multiple transmissions, for example, on multiple DCCH segments. A notification format may include a combination of fixed and configurable fields, for example as shown in FIG. 6 to 8. A notification format can also include only fixed fields or only configurable fields.

In general, any number of notification formats can be defined for a given control channel assignment. Each notification format can be designed for certain operating conditions. In one embodiment, different notification formats may include different notifications that are more appropriate for different operating conditions covered by these notification formats. In another embodiment, different notification formats may have the same set of notifications that may be arranged in different orders and / or have different formats / structures. The division of bits between different notifications may be different for different notification formats. For example, if a DCCH segment has a fixed number of information bits, then an UL request can go from 4 bits to 3 bits, so that another notification can obtain an additional bit. Regardless of how the notification formats can be defined, an appropriate notification format can be selected for use based on the current operating conditions of the terminal.

FIG. 9 shows an embodiment of a notification transmission scheme 900 for a control channel, for example, the DCCH. In this embodiment, a set of notifications is sent on the control channel in each notification interval, which can have any length of time. Each set of notifications is sent using a 910 notification format in a control channel frame. In this embodiment, the notification format 910 includes L notifications that are sent in M periods of time, where, in general, L ≥ 1 and M ≥ 1. A period of time can be any length of time and can cover one or more symbol periods . A period of time may correspond to three half slots, as shown in FIG. 3, or to some other duration of time. The M periods of time may have identical or different durations. Any number of bits of information can be sent in each period of time. Notification format 910 can include any type of notification and any number of notifications of each type. Each notification can be any size and can be sent in one or more time periods. As shown in FIG. 9, notification format 910 is used repetitively in each notification interval. Therefore, the notification x, for x = 1,…, L, is sent in the same location of the control channel in each notification interval.

FIG. 10 shows an embodiment of a notification transmission scheme 1000 for a control channel with selectable notification formats. Initially, at time T1, the operating conditions of the terminal are determined. A notification format A that is appropriate for the current operating conditions is selected for use. A set of notifications is sent at each notification interval using a notification format A. At time T2 changes in operating conditions are detected. A notification format B, which is more appropriate for the new operating conditions, is selected for use. Then, a set of notifications is sent in each notification interval using a notification format B. At time T3 changes in operating conditions are detected again. A notification format C, which is more appropriate for the new operating conditions, is selected for use. Then, a set of notifications is sent in each notification interval using notification format C.

A change in the notification format can be achieved in several ways. In an embodiment shown in FIG. 10, a notification format includes a notification format type field that identifies that notification format. A set of notification formats can be supported. The definition of each notification format in the set can be known a priori by the terminal and the base station, communicated by

signaling during call establishment or at a switching time, sent by broadcasting messages, etc. An appropriate notification format can be dynamically selected in each notification interval and identified by the type of notification format field. In another embodiment, a notification format includes a field indicating a notification format to be used in a subsequent notification interval. In another additional embodiment, a change in the notification format is achieved by exchanging signaling between the terminal and the base station, for example through a traffic channel, which is different from the DCCH, using control messages.

In one embodiment, a terminal may autonomously select a notification format. The terminal can determine its operating conditions (for example, environment, capabilities, etc.) and can select an appropriate notification format based on its operating conditions. In another embodiment, a terminal and a base station may jointly select a notification format. For example, the terminal may determine its operating conditions and suggest a notification format, and the base station may accept or reject the suggested notification format. In another additional embodiment, a base station may select a notification format for a terminal, for example, based on information provided by the terminal.

A terminal may use a notification format until a new notification format is selected, for example due to changes detected in the operating conditions. The terminal can also use multiple notification formats by default. For example, the terminal may alternate between two notification formats A and B, use the notification format A at odd notification intervals and use the notification format B at even notification intervals. The notification format 600 of FIG. 6 is composed of four smaller notification formats, a first notification format for super-slots 0, 2, 4 and 6, a second notification format for super-slots 1 and 5, a third slot format for super-slot 3 and a fourth slot format for super slot 7.

A terminal can have multiple connections with multiple base stations. The terminal can use the same notification format for all base stations or it can use different notification formats for different base stations.

Each notification can have any format / structure that is appropriate for that notification. A notification can carry a single value or multiple values. In one embodiment, one or more query tables can be defined for each type of notification. Each query table can map a calculated value with a notification value with a specific number of bits. As an example, for SNR DL, a query table can map a SNR DL value calculated for a base station with a 5-bit value for a complete SNR DL notification for non-DL macrodiversity, another query table can map the value SNR DL calculated, in addition to determining if the base station is preferred, with a 5-bit value for a complete SNR DL notification for DL macro diversity, another query table can map a delta SNR DL value with a 3-bit value for a notification SNR DL delta, etc. Each query table can be defined to achieve good performance for the corresponding notification. Table 3 shows an example query table that maps an SNR DL value in a range of -13dB to + 29dB with a 5-bit value for a full SNR DL notification. Table 3 also shows an example query table that maps a delta SNR value in a range of -5dB to + 5dB with a 3-bit value for a delta DL SNR notification. Other query tables can also be defined for the other types of notification.

Table 3 5

5 bit SNR DL notification

Rep SNR 3-bit DL

Value

SNR  Value SNR  Value SNR  Value SNR  Value SNR delta

0

-13 dB 8 -4 dB 16 4 dB 24 17 dB  0 -5 dB

one

-11 dB 9 -3 dB 17 5 dB 25 19 dB  one -3 dB

2

-10 dB 10 -2 dB 18 6 dB 26 21 dB  2 -2 dB

3

-9 dB eleven -1 dB 19 7 dB 27 23 dB  3 -1 dB

4

-8 dB 12 0 dB twenty 9 dB 28 25 dB  4 0 dB

5

-7 dB 13 1 dB twenty-one 11 dB 29 27 dB  5 1 dB

6

-6 dB 14 2 dB 22 13 dB 30 29 dB  6 3 dB

7

-5 dB fifteen 3 dB 2. 3 15 dB 31 Reserved s  7 5 dB

In one embodiment, a single dictionary is used for each type of notification. A dictionary for a type of notification defines a specific format / structure for each notification of that type. The dictionary defines how each notification is interpreted. For example, a dictionary for SNR DL may have a format for a 5-bit SNR DL notification for a non-DL macrodiversity, another format for a 5-bit SNR DL notification for DL macro diversity, and another additional format for a SNR DL notification 3 bits The same dictionary, and therefore the same three SNR notification formats, can be used for all notification formats that have SNR DL notifications.

In another embodiment, multiple dictionaries are used for a given type of notification. Each dictionary offers a specific format / structure for each such notification. Multiple SNR dictionaries can be used for SNR notifications. For example, a low mobility SNR notification may use a format other than a high mobility SNR notification. Different query tables can be used for high and low mobility SNR notifications. As another example, an SNR notification for good channel conditions may use a different format than an SNR notification for bad channel conditions. The range of SNR values and / or SNR increment values may be different for different SNR notification formats. Multiple request dictionaries can also be used for UL requests, for example, for different QoS. Each request dictionary can provide certain accumulated delay information (for example, the number of MAC frames and / or delay information) in the terminal and / or use different formats for UL requests. For example, a 4-bit UL request can have different meanings in different request dictionaries. Multiple dictionaries can also be used for other types of notification.

Referring again to FIG. 9, a notification can carry a value that is within a range of values for that notification. The notification value can have different meanings in different dictionaries. Therefore, the information carried in the notification (that is, the actual meaning of the notification value) is determined both by the notification value and by the dictionary used for the notification.

The specific dictionary to use for each notification can be transported explicitly or implicitly. In one embodiment, each notification format uses a specific dictionary for each notification. In this embodiment, the dictionary for each type of notification is implicitly transported by the notification format. For each notification format selected for use, the terminal and the base station know a priori the specific dictionary to be used for SNR DL notifications, the specific dictionary to use for UL requests, etc. The terminal and base station can correctly interpret each notification sent using the selected notification format.

In another embodiment, a dictionary can be selected for each type of notification, regardless of the notification format. For example, multiple request dictionaries may be available for a given notification format. Different dictionaries can be selected for use in different operating scenarios (for example, different mobility). An appropriate dictionary can be selected when changes in operating conditions are detected, for example, together with or independently of the selection of the notification format. The selected dictionary can be transported by signaling or in some other way.

The information bits for notifications can be encoded, modulated and processed in several ways. In one embodiment, the information bits to be sent in a DCCH segment are encoded (for example, with a block code) to generate code bits. The code bits are then mapped with modulation symbols according to a modulation scheme. The modulation symbols are sent in the tone symbols for the DCCH segment. In one embodiment, a sequence of randomization bits is used to randomize the information bits or code bits in some or all of the DCCH segments. For example, the randomization sequence may apply to some notifications and not apply to other notifications. In one embodiment, the randomization sequence is a function of the notification format. In this embodiment, when the notification format changes, the randomization sequence also changes. The randomization sequence can be used to detect a disconnection of states, which is a situation in which a terminal believes it is using a notification format, while a base station believes that the terminal is using a different notification format.

FIG. 11 shows an embodiment of an 1100 process for sending notifications repetitively. A terminal receives an assignment from a control channel (for example, a DCCH) used to send notifications (block 1112). The terminal determines a notification format to be used based on the control channel assignment (block 1114). For example, a first notification format can be used for a complete assignment (for example, full tone) of the control channel, and a second notification format can be used for a

partial assignment (eg split tone) of the control channel. The first and second notification format may include different numbers of control channel segments in a notification interval and / or different numbers of information bits in each control channel segment. The terminal generates a set of notifications for each of a plurality of notification intervals (block 1116). The terminal provides the set of notifications for each notification interval according to the notification format (block 1118). The terminal repeatedly sends a plurality of notification sets in the plurality of notification intervals (block 1120).

The notification format indicates a specific sequence of notifications sent in specific locations of a control channel frame. A control channel frame is a unit of the control channel used to send a set of notifications according to the notification format. The control channel frame may comprise multiple control channel segments, for example, 40 DCCH segments. The notification format may include one or more notifications in each control channel segment.

The notification format may include multiple types of notification, for example SNR, uplink request, available transmission power, interference, delay information, etc., or a combination thereof. The notification format can include any number of notifications of each type, which can be determined according to the importance of such notifications. For example, SNR and uplink request notifications can be sent more often than notifications of other types. The notification format may include multiple notifications of a particular type in different locations of the control channel frame, notifications of different sizes for a given type, etc.

The terminal may determine a dictionary to be used for each type of notification, enter at least one dictionary available for that type of notification. The dictionary for each type of notification defines the format / structure for each notification of that type. The terminal can generate notifications of each type according to the applicable dictionary for that type of notification. Multiple dictionaries can be used for SNR notifications, for example a dictionary for low mobility and another dictionary for high mobility. Multiple dictionaries can also be used for uplink requests for different traffic QoS. Multiple dictionaries can also be defined for other types of notification.

FIG. 12 shows an embodiment of an apparatus 1200 for sending notifications repetitively. The apparatus 1200 includes means for receiving an assignment of a control channel used to send notifications (block 1212), means for determining a notification format to be used based on the assignment of the control channel (block 1214), means for generating a set of notifications for each of a plurality of notification intervals (block 1216), means for arranging the set of notifications for each notification interval according to the notification format (block 1218), and means for sending a plurality of notification sets in the plurality of notification intervals (block 1220).

FIG. 13 shows an embodiment of a 1300 process for sending notifications adaptively depending on the operating conditions. A terminal sends notifications according to a first notification format to a base station (block 1312). The first notification format can be a default notification format

or can be selected based on the current operating conditions. An indication is obtained to use a second notification format (block 1314). The base station can select the second notification format and send signaling with the indication to the terminal. Alternatively, the terminal can select the second notification format and generate the indication. Then, the terminal sends notifications according to the second notification format (block 1316).

In block 1314, the terminal and / or the base station can detect changes in operating conditions, for example based on changes in the terminal environment, the capabilities of the terminal, the traffic QoS for the terminal, etc. The second notification format can be selected based on the changes detected in the operating conditions. For example, changes in terminal mobility can be detected. The second notification format can then be selected based on the mobility changes detected. The first notification format may be suitable for a first mobility condition (for example, stationary or low speed) and the second notification format may be suitable for a second mobility condition (for example, high speed). Changes in the traffic QoS for the terminal can also be detected. The second notification format can then be selected based on the QoS changes detected. The first and second notification format can be designed for different traffic QoS.

Each notification format can be associated with specific dictionaries. Alternatively, dictionaries can be selected independently of the notification format. In any case, the terminal determines the appropriate dictionary to use for each notification in the current notification format. The terminal generates

Notifications of each type according to the dictionary for that type of notification.

The change from the first notification format to the second notification format can be indicated by a field indicating the type of notification format, for example as shown in FIG. 10. The change of notification format can also be achieved by exchanging signaling with the base station.

FIG. 14 shows an embodiment of an apparatus 1400 for sending notifications adaptively. The apparatus 1400 includes means for sending notifications according to a first notification format to a base station (block 1412), means for obtaining an indication for using a second notification format (block 1414), and means for sending notifications according to the second format of notification (block 1416).

Notification techniques can be used to send notifications from a terminal to a base station on the uplink, as described above. Notification techniques can also be used to send notifications from a base station to a downlink terminal.

FIG. 15 shows a block diagram of an embodiment of a base station 110 and a terminal 120 of FIG. 1. At the base station 110, a signaling and transmission data (TX) processor 1510 receives traffic data for the terminals that will be serviced and the signaling will be sent. Processor 1510 processes (for example, formats, encodes, interlaces and maps with symbols) traffic data, signaling and pilot signals and provides output symbols. An OFDM 1512 modulator performs an OFDM modulation on the output symbols and generates OFDM symbols. A transmitter (TMTR) 1514 conditions (for example, converts the OFDM symbols to analog, filters, amplifies and converts upwards) to generate a downlink signal, which is transmitted through a 1516 antenna.

At terminal 120, an antenna 1552 receives downlink signals from base station 110 and other base stations and provides a received signal to a receiver (RCVR) 1554. Receiver 1554 conditions and digitizes the received signal and provides samples. An OFDM demodulator (demod) 1556 performs an OFDM demodulation in the samples and provides frequency domain symbols. A signaling and reception data processor (RX) 1558 processes (for example, unmaps with symbols, deinterlaces and decodes) the frequency domain symbols and provides decoded data and signaling for terminal 120.

On the uplink, a 1570 controller / processor generates notifications according to the notification format and dictionaries selected for use. A signaling and transmission data processor 1560 generates output symbols for traffic data, signaling (for example, notifications) and pilot signals to be sent to the base station 110. An OFDM 1562 modulator performs an OFDM modulation in the output symbols and generates OFDM symbols. A transmitter 1564 conditions the OFDM symbols and generates an uplink signal, which is transmitted through the antenna 1552.

In the base station 110, the uplink signals of terminal 120 and other terminals are received by the antenna 1516, are conditioned and digitized by a receiver 1520, demodulated by an OFDM demodulator 1522, and processed by signaling processor and of reception data 1524 to retrieve traffic data and signaling sent by terminal 120 and other terminals.

Controllers / processors 1530 and 1570 direct the operation of several processing units at base station 110 and terminal 120, respectively. The controller / processor 1570 can carry out the process 1100 of FIG. 11, process 1300 of FIG. 13 and / or other processes to send notifications on the uplink. The controller / processor 1530 can receive notifications from terminal 120 and other terminals and can schedule transmission on the downlink and / or the uplink based on the notifications received from the terminals. Memories 1532 and 1572 store codes and program data for base station 110 and terminal 120, respectively.

The notification techniques described in this document can be implemented in several ways. For example, these techniques can be implemented in hardware, firmware, software or a combination thereof. For a hardware implementation, the processing units in a terminal or a base station to support notifications can be implemented in one or more application-specific integrated circuits (ASICs), digital signal processors (DSP), digital signal processing devices ( DSPD), programmable logic devices (PLD), programmable field gate arrays (FPGA), processors, controllers, microcontrollers, microprocessors, electronic devices, other electronic units designed to perform the functions described in this document, or a combination thereof.

For a firmware and / or software implementation, notification techniques can be implemented with modules (for example, procedures, functions, etc.) that perform the functions described in this document. The firmware and / or software codes can be stored in a memory (for example, memory 1532 or 1572 of FIG. 15) and executed by a processor (for example, processor 1530 or 1570). Memory can

5 be implemented within the processor or be external to the processor.

The above description of the disclosed embodiments is provided to allow any person skilled in the art to carry out or use the present invention. Various modifications of these embodiments will be apparent to those skilled in the art, and the generic principles defined herein may

10 applied to other embodiments without departing from the scope of the invention. Therefore, the present invention is not intended to be limited to the embodiments shown herein, but should be granted the broadest scope compatible with the novel principles and features disclosed herein.

Claims (13)

1.A device (120) for notifying in a wireless communication system, comprising: 5 means for generating a set of notifications for each of a plurality of notification intervals; means for arranging the set of notifications for each notification interval according to a notification format; 10 means for repetitively sending a plurality of notification sets in the plurality of notification intervals; means for receiving an assignment of a control channel used to send notifications; and 15 means for determining the notification format based on the control channel assignment. 2. The apparatus (120) of claim 1, further comprising: 20 means for determining a dictionary to be used for a particular type of notification among multiple dictionaries available for the particular type, in which a dictionary defines how the notification is interpreted; Y means for generating notifications of the particular type according to the dictionary. 25 3. The apparatus (120) of claim 1, wherein: the means to generate the set of notifications, the means to arrange the set of notifications, the means to send repetitively, The means to receive and the means to determine the notification format comprise at least one processor (1570). 4. The apparatus (120) of claim 3, wherein the notification format includes at least one notification in Each of multiple control channel segments, in which the control channel frame comprises multiple control channel segments; and in which each notification can be sent completely in a control channel segment or also in multiple segments. 5. The apparatus (120) of claim 3, wherein the notification format includes multiple types of notification. 40 6. The apparatus (120) of claim 5, wherein the multiple types of notification are for the signal-to-noise ratio (SNR), uplink request, available transmission power, interference, delay information, or a combination thereof. The apparatus (120) of claim 3, wherein the notification format includes multiple notifications of a particular type of notification in different locations of a control channel frame. 8. The apparatus (120) of claim 3, wherein the notification format includes notifications of different sizes for at least one type of notification. fifty 9. The apparatus (120) of claim 3, wherein at least one processor (1570) is configured to determine a dictionary to be used for a particular type of notification from among multiple available dictionaries for the particular type, in which a Dictionary defines how the notification is interpreted, and to generate notifications of a particular type according to the dictionary. 10. The apparatus (120) of claim 3, wherein at least one processor (1570) is configured to use a first notification format as the notification format if a complete assignment that assigns a control channel tone to a user is received by the control channel, and to use a second notification format as the notification format if a partial assignment that assigns a control channel tone to more than one user is 60 receives through the control channel. 11. A method for notifying in a wireless communications system, comprising: generating a set of notifications for each of a plurality of notification intervals; 5 arrange the set of notifications for each notification interval according to a notification format; repetitively send a plurality of notification sets in the plurality of notification intervals; 10 receive an assignment from a control channel used to send notifications; and determine the notification format based on the control channel assignment. 12. The method of claim 11, further comprising: 15 determine a dictionary to be used for a particular type of notification from among multiple dictionaries available for the particular type, in which a dictionary defines how the notification is interpreted; Y generate notifications of the particular type according to the dictionary. twenty 13. A computer-readable medium that includes instructions stored therein, comprising: a first set of instructions for generating a set of notifications for each of a plurality of notification intervals; 25 a second set of instructions for arranging the set of notifications for each notification interval according to a notification format; and a third set of instructions for directing the repetitive transmission of a plurality of notification sets in the plurality of notification intervals; 30 additional instructions for receiving an assignment of a control channel used to send notifications and to determine the notification format based on the assignment of the control channel. 14. Software comprising instructions for carrying out the steps of claim 11 or 12.