HK1190024A - Methods for control signaling for wireless systems - Google Patents

Description

Method for control signaling for wireless systems

The present application is a divisional application of patent applications having an application number of 200980116853.9, an application date of 2009, 3/10, and an invention name of "method for control signaling for wireless system".

This application claims the benefit of U.S. provisional patent application serial No. 61/035,363 filed on 10.3.2008, which is hereby incorporated by reference in its entirety.

Technical Field

The present disclosure relates to a method of control signaling for a wireless system.

Background

In most wireless communication systems, one or more base stations facilitate wireless communication with any number of mobile stations over a wireless interface. A significant amount of information must be exchanged between the base station and the various mobile stations to enable communication therebetween. This information is generally defined as control information. A typical wireless communication system is defined by the Institute of Electrical and Electronics Engineers (IEEE) 802.16 standard, as set forth by the broadband wireless access working group for wireless Metropolitan Area Networks (MANs). The IEEE802.16 standard, commonly referred to as WiMAX, stands for worldwide interoperability for microwave access.

The system requirements of the IEEE802.16 standard are set forth in the IEEE802.16m standard, and like many other wireless communication systems, much of the control information for system access, transmission and reception of traffic packets, and handover from one base station to the next is often transmitted and retransmitted to laughter ground regardless of whether the mobile station actually needs to receive the information. In many cases, the mobile station is in a sleep or idle mode, or has received and stored the control information. Thus, the mobile station does not need to over-retransmit control information or the mobile station has received over-retransmission of control information, which significantly increases control overhead, wastes communication resources, and compromises power efficiency because the mobile station must remain awake to receive and process unnecessary or already available control information.

Accordingly, there is a need for a technique to more efficiently propagate control information to mobile stations in an efficient and effective manner in a wireless communication environment, including those defined by the IEEE802.16 standard and other standards. There is a further need for a technique to ensure that the mobile station efficiently obtains control information when needed, while reducing the need to receive and process control information that has already been received or is otherwise not relevant to operation.

Disclosure of Invention

To efficiently and effectively provide control information, a Broadcast Pointer Channel (BPCH) may be used to identify the type and possibly relative location of control information provided in a given frame structure (e.g., subframe, frame, or superframe). A subframe (or framing-like entity such as a frame or superframe) may have a BPCH and a corresponding system control information segment in which control information may be located. The system control information segment may have any number of control information blocks, where each control information block present may correspond to a particular type of control information. The BPCH is used to identify the type of control information present in the corresponding system control information segment and, if needed or desired, the relative location of the various control information.

For example, the BPCH may include presence flags for different types of control information, where the presence flags are set according to the presence or absence of corresponding control information in the system control information segment. If the system control information segment of a frame includes certain control information in the corresponding control information block, the BPCH may have a flag corresponding to this control information set to indicate the presence of such information, while other flags corresponding to other types of control information are set to indicate the absence of other types of control information. The BPCH may also provide the location, length, etc. of the corresponding control information block within the system control information segment so that the mobile station can determine the precise location of the control information in the system control information segment. Each control information block may correspond to a different type of control information or a set of control information types.

The mobile station can quickly and efficiently determine what control information is present in the subframe, whether the control information present is relevant, and the location of any or all of the control information in the subframe. Thus, the mobile station can avoid decoding irrelevant control information. In practice, this means that once it is determined whether a subframe contains relevant control information, the mobile station can quickly assess the need to decode the remainder of the subframe or at least a portion of the subframe relevant to the control information.

Those skilled in the art will appreciate the scope of the present invention and realize additional aspects thereof after reading the following detailed description in association with the accompanying drawing figures.

Drawings

The accompanying drawings incorporated in and forming a part of the specification illustrate several aspects of the present invention and, together with the description, serve to explain the principles of the invention.

Fig. 1 is a block diagram representation of a communication environment according to one embodiment of the present disclosure.

Fig. 2 is a block diagram representation of a base station according to one embodiment of the present disclosure.

Fig. 3 is a block diagram representation of a mobile station according to one embodiment of the present disclosure.

Fig. 4A and 4B illustrate a subframe configuration according to one embodiment of the present disclosure.

Fig. 5A and 5B represent a subframe configuration according to a second embodiment of the present disclosure.

Detailed Description

The embodiments set forth below represent the necessary information to enable those skilled in the art to practice the invention and illustrate the best mode of practicing the invention. Upon reading the following description in light of the accompanying drawing figures, those skilled in the art will understand the concepts of the invention and will recognize applications of these concepts not particularly addressed herein. It should be understood that these concepts and applications fall within the scope of the disclosure and the accompanying claims.

Before going into the details of the present invention, an overview of a typical communication environment in which the present invention may be utilized is described. Referring specifically to fig. 1, a portion of a cellular network is depicted in which a Base Station Controller (BSC) 10 serves a plurality of cells 12. Each cell 12 represents the primary coverage area of a particular Base Station (BS) 14, the particular Base Station (BS) 14 operating under the control of a BSC 10. The base stations 14 are capable of facilitating two-way communication with Mobile Stations (MSs) 16 via any number of communication techniques, the Mobile Stations (MSs) 16 being within communication range of the base stations 14 and thus within the respective cells 12. Communications throughout the cellular network may support voice, data, and media communications.

Referring specifically to fig. 2, a base station 14 configured according to one embodiment of the present disclosure is illustrated. Notably, the base stations 14 can support any type of wireless communication technology, such as conventional cellular technologies utilizing Orthogonal Frequency Division Multiple Access (OFDMA), Code Division Multiple Access (CDMA), and Time Division Multiple Access (TDMA), as well as local wireless technologies. Although not limited thereto, the inventive concept is applicable to the IEEE802.16 standard as set forth by the broadband wireless access working group of wireless Metropolitan Area Networks (MANs), and in particular to the system requirements of the IEEE802.16 standard as set forth in the section IEEE802.16 m. The entire contents of this family of standards are incorporated herein by reference. Notably, the technology defined by the IEEE802.16 family of standards is commonly referred to as WiMAX (worldwide interoperability for microwave access).

Thus, the base station 14 may act as any wireless access point that supports wireless communications. The base station 14 will preferably be able to support unicast, multicast and broadcast communications and cause the necessary control signaling to enable and control them. The base station 14 generally includes a control system 20, a baseband processor 22, transmit circuitry 24, receive circuitry 26, one or more antennas 28, and a network interface 30. The receive circuitry 26 receives radio frequency signals carrying information from one or more remote transmitters provided by the mobile station 16. Preferably, a low noise amplifier and filter (not shown) cooperate to amplify and remove broadband interference from the signal for processing. Down conversion and digitization circuitry (not shown) will then down convert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams.

The baseband processor 22 processes the digitized received signal to extract the information or data bits conveyed in the received signal. This processing typically includes demodulation, decoding, and error correction operations. Thus, the baseband processor 22 is typically implemented in one or more Digital Signal Processors (DSPs). The received information is then sent to a core network or communicated to another mobile station 16 served by the base station 14 via the network interface 30. The network interface 30 will typically interact with the core network via the base station controller 10.

On the transmit side, the baseband processor 22 receives digitized data, which may represent voice, data, or control information, from the network interface 30 under the control of the control system 20. The baseband processor encodes the data for transmission. The encoded data is output to transmit circuitry 24 where it is used by a modulator to modulate a carrier signal at one or more desired transmit frequencies. A power amplifier (not shown) will amplify the modulated carrier signal to a level suitable for transmission and deliver the modulated carrier signal to one or more antennas 28 through a matching network.

Referring to fig. 3, a mobile station 16 configured according to one embodiment of the present disclosure is illustrated. The mobile station 16 will support a communication technology compatible with the base station 14. The mobile station 16 will include a control system 32, a baseband processor 34, transmit circuitry 36, receive circuitry 38, one or more antennas 40, and user interface circuitry 42. The control system 32 will have a memory 44 for storing the necessary software and data required for operation. The receive circuitry 38 receives radio frequency signals carrying information from one or more remote transmitters provided by the base station 14. Preferably, a low noise amplifier and filter (not shown) cooperate to amplify and remove broadband interference from the signal for processing. Down conversion and digitization circuitry (not shown) will then down convert the filtered, received signal to an intermediate or baseband frequency signal, which is then digitized into one or more digital streams. The baseband processor 34 processes the digitized received signal to extract the information or data bits conveyed in the received signal. This processing typically includes demodulation, decoding, and error correction operations. The baseband processor 34 is typically implemented in one or more Digital Signal Processors (DSPs).

For transmission, the baseband processor 34 receives digitized data, which may represent voice, data, media, or control information, from the control system 32, and the baseband processor 34 encodes the data for transmission. The encoded data is output to transmit circuitry 36 where it is used by a modulator to modulate a carrier signal at one or more desired transmit frequencies. A power amplifier (not shown) will amplify the modulated carrier signal to a level suitable for transmission and deliver the modulated carrier signal to one or more antennas 40 through a matching network. Various modulation and processing techniques available to those skilled in the art may be applied to the present invention.

Various techniques are disclosed herein for enhancing the control signaling that must occur between the base station 14 and the mobile station 16 to support overall system operation. These techniques, individually or in combination, may reduce control overhead in the mobile station 16 and the base station 14, save power, reduce processing requirements, allow faster network entry, save network resources, or any combination thereof. The control signaling allows the base station 14 and the mobile station 16 to communicate with each other to exchange important information and operational instructions, referred to as control information. Because the base station 14 typically controls communications, a large portion of the control information is disseminated by the base station 14 to the mobile stations 16. The control information may be used to control system access, transmission and reception of traffic packets, handovers, and the like.

Since the control information is varied in nature, different types of control information have different characteristics. For example, different types of control information vary in terms of changing frequency, whether it is unicast, multicast or broadcast, how robust it is needed, its importance for system access, etc. Thus, different types of control information are treated differently. The following description classifies various types of control information, and based on how the information is classified, delivery of control information is implemented accordingly.

To provide insight and inefficiencies of the emergent techniques, scheduling control and system information currently provided in the ieee802.16e standard is referenced. According to the ieee802.16e standard, scheduling information is transmitted in a MAP message, and system information is transmitted in a separate uplink or downlink channel. In addition, neighbor base station information and paging information are broadcast in a separate message. A large amount, if most, of this information is retransmitted periodically, regardless of whether it is actually needed. For example, some information provided in the MAP message, such as space-time coding information, ranging (ranging) region information, and fast feedback ranging definitions, need not be dynamic and thus are sent less frequently to reduce overhead. Some of the information provided in the uplink and downlink channels is static and therefore does not require the base station 14 to periodically broadcast to mobile stations 16 that have entered the network, or to broadcast at a greatly reduced rate. Such static information may include a base station identifier, an operator identifier, a subnet identifier, and a time division duplex ratio.

Some of the information provided in the uplink and downlink channels is semi-static and therefore need not be broadcast periodically by the base station 14 to the mobile stations 16 if the information is not changed, at a greatly reduced rate, or may be broadcast when the information changes. Such information may include burst profile (burst profile) and handover parameters. Similarly, the information of neighboring base stations is typically semi-static and need not be periodically broadcast to mobile stations 16 that have entered the network, assuming the information has not been changed. As can be seen from the above, the need to provide or update control information changes. While certain control information changes frequently, other control information may only change periodically, if at all.

For example, the control information can be classified as relatively static, semi-static, or dynamic. The static control information is relatively fixed. The semi-static control information will change on a periodic basis or in response to defined events. Dynamic control information is information that may change on a relatively continuous basis.

Whether static, semi-static, or dynamic, control information is typically delivered at defined locations in a framing structure, where certain information is provided somewhere in a frame or group of frames each time the frame or group of frames is transmitted. Although it may be necessary to continuously provide dynamic control information, continuously retransmitting static and semi-static control information that has not changed since the last transmission is very inefficient from both a processing perspective and a resource perspective.

With the present invention, different types of control information can be transmitted at different times to increase efficiency. For example, control signaling overhead may be reduced by having the base station 14 transmit static system-wide information that provides basic physical layer configuration information needed to perform initial system access procedures in response to the base station 14 detecting that the mobile station 16 is attempting to enter the network. This is in contrast to having the base station 14 transmit such information in every frame or subframe regardless of network events or conditions. The mobile station 16 uses the physical layer configuration information to establish communication with the base station 14 for network entry to the network supported by the base station 14. The base stations 14 are capable of communicating static system-wide information that provides a Machine Access Code (MAC) or other upper layer configuration information after the mobile stations 16 perform initial system access using physical layer configuration information. Upper layer configuration information is not required for initial system access and can be unicast to the appropriate mobile stations 16 to further increase overall system efficiency.

In the above case, the base station 14 may broadcast uplink ranging (or random access) information for use by mobile stations 16 entering the network in initiating an uplink ranging (or random access) procedure. A mobile terminal 16 entering the network will receive the uplink ranging (or random access) information and use it to initiate the uplink ranging procedure required to enter the network, where the procedure assumes uplink transmission based on the uplink ranging or random access information, as is known in the art.

In the ieee802.16m standard, the framing structure is as follows. A superframe consists of 4 frames and is transmitted every 20 milliseconds. Each frame has 8 subframes and is transmitted every 5 milliseconds. Each subframe typically corresponds to 5, 6, or 7 OFDM symbols.

The following provides an exemplary way of classifying different types of control information into 7 different categories and controlling the dissemination of the control information based on the respective categories. Delivery of various types of control information may be based on appropriate events, conditions, or scheduling criteria. For the following example, an ieee802.16m framing structure is used; however, those skilled in the art will appreciate the applicability of these concepts to different types of framing structures.

The type 1 control information is considered static and corresponds to the basic system-wide physical layer information used by the mobile station 16 to decode downlink physical layer frames/subframes received from the base station 14. Typical control information includes bandwidth configuration information, CP size, multi-carrier configuration information, system time, Time Division Duplex (TDD) ratio information, guard tone (guard tone), and the like. Type 1 control information typically includes static system-wide deployment specific parameters that are required for fast initial access during network entry. The mobile station 16 should be able to decode the type 1 information after synchronizing with the one or more serving base stations 14. The type 1 control information should be delivered with very high reliability and can be broadcast periodically or in association with an initial ranging event. If broadcast periodically, this information should be carried in fixed resource locations within the superframe. The presence or absence of control information is signaled through a Broadcast Pointer Channel (BPCH) if broadcast in association with an initial ranging event, which will be described in more detail below.

Type 2 control information is considered pseudo-dynamic (or aggressive semi-static) and may vary from one superframe to another, but does not change from one subframe to another, or is even provided in subframes of any superframe or superframe. Type 2 information corresponds to substantially full sector (sector-wide) physical layer information used by the mobile station 16 to decode the downlink physical layer frame/subframe. The type 2 information may include channelization information, legacy and 802.16m resource partitioning information, subframe control configuration information, superframe configuration control information, and the like. The channelization information may relate to partitions of a diversity zone, a local zone (localized zone), and information, pilot structure and information, etc. The type 2 information may also contain initial ranging region or code information that allows the mobile station 16 to facilitate a fast initial access procedure as set forth in the IEEE802.16 standard. Since type 2 control information is typically needed for fast initial access during network entry and handover, the mobile station 16 should be able to decode this information after synchronizing and receiving the type 1 information. As indicated, type 1 information may change from superframe to superframe and thus, this information should be broadcast periodically every superframe, either in fixed resource locations within a superframe or at the boundary of a superframe, where the mobile stations 16 know the fixed resource locations. Like type 1 information, type 2 information should be delivered with very high reliability.

Type 3 control information is considered static and corresponds to non-physical layer system information such as a base station identifier, operator identifier, subnet identifier, and the like. This control information does not have to be broadcast periodically to the mobile station 16 and can be unicast to the mobile station 16 during the initial network entry procedure. In addition, this information need not be provided in fixed resource locations in a superframe, frame, or subframe.

The type 4 control information is semi-static physical layer or MAC layer configuration information such as a handover parameter, a power control parameter, fast feedback region information, ranging region information, and the like. Type 4 control information changes in a relatively slow manner on the order of seconds, minutes, or hours, as opposed to dynamic control information, which may be changing and needs to be updated in a time period of less than 100 milliseconds. It is not necessary for a mobile station 16 that has entered the network to broadcast type 4 information in a frequent manner, assuming that the information has not changed. The design of the control channel should support efficient power savings for the sleep and idle modes of the mobile station 16 while ensuring that the mobile station 16 receives any changes in the system configuration in a timely manner. For mobile stations 16 performing initial network entry, after the base station 14 has completed the initial ranging procedure with a particular mobile station 16, type 4 information may be sent as a unicast message to each mobile station 16 during network entry to expedite network entry.

The type 5 control information relates to information about the neighbor base station 14 of the serving base station 14 or is related to the neighbor base station 14 about the serving base station 14. The type 5 information may include static information corresponding to the type 3 information or semi-static information corresponding to the type 4 information. The type 5 control information may be broadcast periodically or in response to an event. The type 5 control information may also be unicast to any mobile station 16 that wants to add a neighboring base station 14 to the active set of base stations 14 currently serving the mobile station 16.

Type 6 control information is semi-static and can be event-driven paging information. Regardless of quick paging or regular (regular) paging information, type 6 control information is typically not periodic and should be broadcast whenever there are one or more mobile stations 16 to page, typically in association with at least one mobile station 16 entering the network.

The type 7 control information is dynamic and related to downlink and uplink resource allocation and traffic burst assignment (assignment) information such as MCS, Multiple Input Multiple Output (MIMO) mode, user identifier, resource allocation, etc. The type 7 control information may also contain Acknowledgement (ACK) and Negative Acknowledgement (NAK) of the uplink traffic and power control information for the uplink traffic. The type 7 control information may change every subframe and the type 7 control information is unicast to the mobile station 16 if the traffic burst is unicast or multicast/broadcast to a group of mobile stations 16 if the traffic burst is multicast/broadcast. Resource location information for one or more mobile stations 16 served by the base station 14 may be multicast to the set of mobile stations 16.

In order to efficiently and effectively provide control information, a Broadcast Pointer Channel (BPCH) is used to identify the type and possibly relative position of control information provided in a given frame structure, such as a subframe, frame or superframe. In operation, the base station 14 will identify control information to provide in each subframe, generate subframes and transmit subframes in a sequential manner. For example, it is assumed that control information corresponding to any one or more of control information types 1, 3,4, 5, and 6 may exist in a subframe or superframe boundary of the ieee802.16m frame structure. Thus, type 3 and 4 control information may be provided in a first subframe, and type 1 control information may be provided in a subsequent subframe, which may not include type 3 and 4 control information. In one configuration, the BPCH does not identify type 2 and 7 information.

A subframe (or like framing entity, such as a frame or superframe) may have a BPCH and a corresponding system control information segment in which control information is stored. As described above, the BPCH is not required every subframe and the control information provided in the system control information may vary. The system control information segment may have any number of control information blocks, where each control information block present may correspond to a particular type of control information. The BPCH is used to identify the type of control information present in the corresponding system control information segment and, if needed or desired, the relative location of the different control information. For example, the BPCH may include presence flags for different types of control information, where the presence flags are set according to the presence or absence of corresponding control information in the system control information segment. If the control information segment of a frame includes type 3,4, and 5 control information in the corresponding control information block, the BPCH may have flags corresponding to the type 3,4, and 5 control information set to indicate the presence of such information, while other flags corresponding to other types of control information are set to indicate the absence of other types of information. The BPCH may also provide the location, length, etc. of the corresponding control information block within the system control information segment so that the mobile station 16 can determine the precise location of the control information within the system control information segment. Each control information block may correspond to a different type of control information or a set of control information types.

With this configuration, the mobile station 16 can quickly and efficiently determine what control information is present in a subframe, whether the control information present is relevant, and the location of any or all of the control information in the subframe. Thus, the mobile station 16 can avoid decoding irrelevant control information. In practice, this means that once it is determined whether a subframe contains relevant control information, the mobile station 16 can quickly assess the need to decode the remainder of the subframe or at least part of the subframe to which the control information relates.

The ability to efficiently determine whether relevant control information is present in a subframe and relevant is particularly advantageous when the mobile station 16 is inactive or in a sleep or idle mode. This may be done by monitoring the BPCH. In these modes, the mobile station 16 is not actively engaged in supporting voice, data, or media communications, but will wake up periodically to obtain or check for relevant control information. If the BPCH in the subframe being monitored indicates that no control information is present or that control information is present but is not relevant for that particular mobile station 16, the mobile station 16 can quickly return to sleep or idle mode without decoding the remainder of the subframe, including any control information that is present but not relevant and any resources and allocation information that may be provided in other portions of the subframe (type 7). The faster the mobile station 16 can return to the sleep or idle mode, the more power is saved.

When the BPCH in the subframe indicates that control information is present and the mobile station 16 determines that the present control information is relevant to the mobile station 16, the mobile station 16 can decode the control information. In some configurations, the mobile station 16 can selectively decode only the relevant one of the control information, so that when the system control information segment has both relevant and irrelevant control information, the mobile station 16 can decode the relevant control information without decoding the irrelevant control information and any resources and allocation information provided in other parts of the subframe (type 7). The mobile station 16 can further save power by eliminating the need to decode irrelevant control information. Furthermore, when different types of control information are present (whether in an allocated control information block or in addition thereto), the BPCH may provide sufficient information for the mobile station 16 to determine the location of the relevant control information in order to avoid the need to decode irrelevant control information. Thus, based on the BPCH, the mobile station 16 can selectively decode all or a portion of any control information present in the subframe. Importantly, all subframes need not have control information at all in the system control information segment, let alone a particular type of control information.

As with the control information, the BPCH may or may not be present in each subframe. The following examples illustrate two configurations for detecting the presence of BPCH. For the first configuration, refer to fig. 4A and 4B. In this configuration, the subframe includes a control segment, an optional BPCH segment, an optional system control information segment, and a traffic segment for a traffic burst. The control section may contain information for traffic bursts regarding the partitioning of resources within a subframe. The control segment may have a fixed length and position, which is known to the mobile station 16. The control segment is encoded and modulated in a known manner. The traffic segment carries information defining the resource allocation for the traffic burst.

A BPCH presence flag is added to the control segment of the subframe to indicate the presence or absence of a BPCH and possibly the type and location of control information, if any, that follows in the system control information segment. When present, the BPCH may have a fixed length and position, which is known to the mobile station 16. The BPCH may be encoded and modulated in a known manner. In operation, the mobile station 16 processes the subframes as follows. First, the mobile station 16 will decode the control segment and analyze the BPCH present flag to determine whether the subframe includes a BPCH. If the BPCH present flag (1) indicates that a BPCH is present in a subframe, as shown in fig. 4A, the mobile station 16 will decode and process the BPCH so that all or any relevant control information in the system control information segment can be decoded. The mobile station 16 then uses any relevant control information as needed. The remaining resources in the traffic segment are for traffic bursts and are partitioned based on information in the control segment. The mobile station 16 will process the traffic burst in a conventional manner based on the control segment information.

If the presence flag (0) indicates that the BPCH is not present in the subframe, as shown in fig. 4B, the mobile station 16 will be aware that the BPCH and associated system control information segment are not present in the subframe. The remaining resources in the traffic segment are for traffic bursts and are partitioned based on information in the control segment. The mobile station 16 will process the traffic burst in a conventional manner based on the control segment information.

In the above configuration, a BPCH presence flag is provided in the control segment to indicate whether the BPCH, and thus the system control information segment, is present in the subframe. In the configuration of fig. 5A and 5B, no flag is present with the BPCH. If a BPCH is present, it will be provided at a fixed position in the subframe and will have a fixed length and be provided with a fixed modulation and coding scheme (fig. 5A). In operation, the mobile station 16 will first attempt to decode the BPCH at the location in the subframe where it is expected to find the BPCH. If the decoding is successful, the information provided in the BPCH will allow the mobile station 16 to identify and decode all or the relevant control information provided in the system control information segment, as described above. If the decoding is unsuccessful, the mobile station 16 will determine that the BPCH is not present and, thus, no control information is provided in the control segment (FIG. 5B). The mobile station 16 will then continue to decode the control segment and the traffic burst provided in the traffic segment of the subframe.

With semi-static control information, such as information types 4 and 5 and possibly type 2, the base station 14 may take action to inform the mobile station 16 about when the control information changes to achieve further power savings by avoiding the need for the mobile station to decode control information that has not changed or updated. The control information, version information, and action time for the control information may be sent from the base station 14 to the mobile station 16 at the same or different times in the same or different messages. When updating the control information, a new version number is assigned to the control information so that each version of the control information can be identified and tracked. The version number is referred to herein as a System Configuration Change Count (SCCC). The action time identifies when the configuration information should be in effect or valid. Typically, control information is downloaded by the mobile station 16 and executed at action time. Prior to the action time, the mobile station 16 will use the previous version of the control information.

In one configuration, the mobile station 16 may store current control information that is currently valid and new control information that will take effect in the future at the specified action time in the memory 44 of the control system 32. As shown in fig. 3, the current control information (ci (a)) has a first SCCC (a)), and the new control information (ci (b)) has a second SCCC (b)) that is different from the first SCCC. Periodically and in a frequent manner, the base station 14 may transmit a current SCCC to identify valid current control information and a System Configuration Change Alarm (SCCA) flag to indicate whether new control information (which is different from the current control information) is provided by the base station 14. Also, the new control information is typically control information that is scheduled to occur in the future. For example, SCCC and SCCA flags may be provided for each superframe in the corresponding superframe configuration control (type 2) information.

By detecting the current SCCC value provided by the base station 14, the mobile station 16 knows the current control information that should be valid and currently used. Assuming that the mobile station 16 receives and stores the current control information, the mobile station 16 will use the current control information until the action time occurs when the new control information is downloaded and a switch to the new control information occurs. When this action time occurs, the new control information will become the current control information. If the mobile station 16 detects an SCCC value provided by the base station 14 that corresponds to control information other than the control information being used, the mobile station 16 will switch to the appropriate control information if such control information is available in the memory 44, or cease uplink transmission to the base station 14 and attempt to decode the appropriate control information for downlink transmission from the base station 14. Upon recovery of the appropriate control information, the mobile station 16 will resume uplink transmissions to the base station 14.

By monitoring the SCCA flag, the mobile station 16 is able to determine whether the base station 14 is broadcasting new control information that is ultimately used in place of the current control information. If the SCCA flag indicates that new control information is being broadcast, the mobile station 16 will attempt to decode broadcast messages in the current and subsequent subframes that include control information of interest until the new control information is successfully decoded and stored in the memory 44.

When operating in the active or normal mode, the mobile station 16 may operate as follows to support power saving efforts. The following operational assumptions: the mobile station 16 is using current control information corresponding to the current SCCC currently being provided by the base station 14. If the SCCA flag indicates that no new control information is being broadcast, the mobile station 16 need not decode the corresponding control information being provided by the base station 14. If the SCCA flag indicates that new control information is being broadcast and if the mobile station 16 previously successfully decoded new control information associated with the new SCCC, the mobile station 16 need not decode the new control information being provided by the base station 14. Thus, certain subframes or portions thereof that include new control information need not be decoded. If the SCCA flag indicates that new control information is being broadcast and if the mobile station 16 has not previously successfully decoded new control information associated with the new SCCC, the mobile station 16 should decode the new control information being provided by the base station 14. Such decoding may require decoding the BPCH to determine the presence and location of the desired control information in the system control information segment. Thus, some subframes or parts thereof providing new control information should be decoded.

When operating in the sleep or idle mode, the mobile station 16 may operate as follows to support power saving efforts. The base station 14 will periodically transmit control information. The mobile station 16 will periodically wake up at a time period set by the base station 14 to attempt to decode the current SCCC and SCCA signatures being transmitted in the corresponding control information. Preferably, the wake-up time will coincide with the time when the SCCC and SCCA indicia are broadcast by the base station 14.

If the mobile station 16 detects that the SCCC being broadcast is different from the SCCC used for control information stored by the mobile station 16, the mobile station 16 should wake up during the current subframe and remain awake during subsequent subframes to obtain the current control information corresponding to the SCCC being broadcast by the base station 14. Such decoding may require decoding the BPCH to determine the presence and location of the desired control information in the system control information segment. Once the current control information is obtained, the mobile station 16 will execute the current control information and begin uplink transmission or return to a sleep or idle mode.

Assuming that the mobile station 16 has current control information based on the SCCC being broadcast by the base station 14 and uses this current control information, the following operations may be provided to enhance power savings during sleep or idle mode. If the SCCA flag indicates that new control information is being broadcast and if the mobile station 16 has not previously successfully decoded new control information associated with a new SCCC, the mobile station 16 can wake up during the current subframe and remain awake until it decodes the new control information being provided by the base station 14. Also, such decoding may require decoding the BPCH to determine the presence and location of the desired control information in the system control information segment. If the SCCA flag indicates that no new control information is being broadcast, the mobile station 16 need not decode the corresponding control information being provided by the base station 14 and can return to a sleep or idle mode, assuming that the mobile station 16 is within a normal sleep window or paging unavailable window, without decoding subsequent subframes.

As can be seen from the above, control information may be categorized and delivered at different times depending on the characteristics of the control information, the operating mode of the mobile station 16, and so on. Several examples are provided below for allowing a mobile station 16 to gain entry into the network and thus allow a particular base station 14 to initiate traffic communications. The typical species described above is used. For the first example, it is assumed that substantially static type 1 information, defined as substantially system-wide physical layer information used to decode a downlink physical layer frame or subframe, is broadcast in response to an initial ranging event triggered by the act of a mobile station 16 within range of a base station 14 initiating communication. In addition, it is assumed that the presence or absence of type 1, 3, and 4 control information is signaled by the BPCH and provided in the system control information segment as described above. Type 2 information is broadcast in a fixed location per superframe.

Initially, the mobile station 16 will synchronize with a preamble or synchronization channel being provided by the base station 14. The mobile station 16 will decode the available type 2 control information and obtain the relevant ranging region information. The ranging region information is provided by the base station 14 as control information and must be used by the mobile station 16 when performing the uplink ranging procedure. Therefore, the mobile station 16 will use the ranging region information to perform an uplink ranging procedure. The base station 14 will detect the uplink ranging attempt by the mobile station 16 and will transmit type 1 control information. The mobile station 16 will decode the type 1 control information. The mobile station 16 will continue its ranging procedure and then obtain any available type 3 and type 4 control information that is unicast by the base station 14 to the mobile station 16. Type 3 and type 4 control information may be conveyed on downlink physical layer frames being provided to the mobile station 16.

For the second example, it is assumed that substantially static type 1 information is periodically broadcast to mobile stations 16 within range of the base station 14. In addition, it is assumed that type 1 control information is provided in a fixed resource location within a superframe, and the use of BPCH is not necessary for the type 1 control information. The BPCH may be used for type 3 and 4 control information. Type 2 information may be broadcast in a fixed location per superframe.

Initially, the mobile station 16 will synchronize with the preamble or synchronization channel being provided by the base station 14. Once synchronized, the mobile station 16 will decode type 1 information from the fixed resource location of a particular superframe and then preferably decode type 2 control information using the BPCH. If a BPCH is used, the mobile station 16 will identify the location of the type 2 control information in the system control information segment of the subframe based on the BPCH and then decode the type 2 control information accordingly. Based on the ranging information provided in the type 2 control information, the mobile station 16 may then perform any uplink ranging procedures. Once uplink ranging is complete, the mobile station 16 may obtain type 3 and type 4 control information that is unicast from the base station 14 in the downlink physical layer subframe. Again, by using the BPCH as described above, type 3 and type 4 control information can be obtained.

Certain aspects of the above configuration may be utilized in a multi-carrier environment. A multi-carrier environment is an environment that allows a mobile station 16 to simultaneously receive information transmitted on two or more different carriers. For example, the 10MHz spectrum can be divided into 25 MHz carriers to support both 5MHz capable mobile stations 16 and 10MHz capable mobile stations 16. A mobile station 16 having a multi-carrier mode is capable of receiving information on both the 5MHz carrier and the 10MHz carrier. Not all carriers need to carry control information redundantly. For example, system-wide and sector-wide system information is common to all carriers. Thus, there is no need to transmit the base station ID on all carriers, as the base station ID will remain the same regardless of which carrier or carriers are being used. Repeating control information over multiple carriers only increases overhead. Thus, at least two carrier types can be defined: primary carrier (primary carrier) and secondary carrier (secondary carrier). The primary carrier may carry a synchronization channel (or preamble), all system information, neighbor base station information, paging information, and resource allocation and control information, which generally correspond to all kinds of control information described above. Thus, the primary carrier may be used to carry type 1 to type 7 control information. The secondary carrier may carry only a subset of the system information, e.g., type 2 control information, which is related to the superframe configuration on the secondary carrier; and resource allocation and control information, e.g., type 7 information, for each subframe within the carrier. This type of carrier may also carry synchronization channel (or preamble) information. Regardless of the configuration, different primary and secondary carriers need not carry the same control information.

In general, one or more carriers within the spectrum can be designated as primary carriers, while one or more carriers within the spectrum can be designated as secondary carriers. A mobile station 16 with the capability to transmit and receive on a single carrier at a time is assigned to the primary carrier. A broadband mobile station 16 capable of transmitting and receiving on multiple carriers at a time is assigned to one or more primary carriers and one or more secondary carriers. Based on the above assignments, the base station 14 may provide system broadcast information, e.g., type 1-6 control information, and resource allocation and control information, e.g., type 7 control information, on the primary carrier. Superframe configuration information, such as type 2 control information, may be transmitted at a superframe boundary through the secondary carrier. Thus, the broadband mobile station 16 will monitor the assigned primary carrier for system control information as well as resource allocation and control information and monitor the secondary carrier for superframe configuration.

Depending on how the base station 14 instructs the mobile station 16, channel information such as Channel Quality Information (CQI) for one or more carriers may be fed back over any one carrier. When configured to feed back the CQI for the secondary carrier, the mobile station 16 must measure the channel quality associated with each carrier. For example, the CQI of the primary carrier should be quantized based on the preamble or pilot symbols received via the primary carrier, and the CQI of the secondary carrier should be measured based on the preamble or pilot symbols received via the secondary carrier.

Those skilled in the art will recognize improvements and modifications to the embodiments of the present invention. All such improvements and modifications are considered within the scope of the concepts disclosed herein and the claims that follow.

Specification accessory

IEEE802.16m control framework

The technical problem is as follows:

different aspects of the control signaling mechanism between the BS and MS are presented to support system operation, including system configuration, resource allocation/control, paging, MS network entry, power save mode, multi-carrier operation. The proposed scheme considers the reduction of control overhead, the realization of power saving, the reduction of MS processing requirements, and the realization of fast network entry for MS.

What solutions have been tried and why do they fail to work?

Here is a list of current solutions and problems:

● in existing systems such as WiMAX and UMB, some static system information is broadcast periodically even if an MS that has entered the network does not need to read it again.

● the concept of a pilot channel is known and has a similar function to the BPCH we propose here, i.e. a channel indicating the presence of a particular type of control information in a frame. However, a known pilot channel exists in each frame, and the method proposed in this application allows the BPCH to exist only when necessary to reduce overhead.

● the concept of primary and secondary carriers is known. However, no specific mapping of what control information is carried on the primary and secondary carriers is given. In this application, we classify different types of control information and propose how to map them to primary and secondary carriers. Load balancing (load balancing) schemes over multiple carriers are known. These do not provide a solution with respect to control signaling. Common layer2/3protocol (common layer2/3 protocol) is known for anchoring (anchor) multiple carriers. The common layer2/3protocol performs resource management and other system management for all carriers. No specific control signaling scheme is proposed, which is proposed in the present application.

● existing systems such as WiMAX and UMB do not have an efficient power saving way for an MS in different power saving modes to keep track of whether it has the latest system information.

Specific elements or steps for solving a problem and how they solve the problem

To reduce the broadcast control signaling overhead, we propose to have the BS transmit static system-wide information only when the BS detects that there is an MS attempting to enter the network. There are two general types of static system-wide information. The first is basic physical layer configuration information required for initial system access. The second is MAC/upper layer information that is not needed for initial system access. For the former, once the BS detects that one or more MSs attempt network entry, the BS must broadcast the information. For the latter, the BS unicasts the information to the MS after the MS has performed initial system access.

In order for the BS to detect whether one or more MSs attempt to enter the network, the BS periodically broadcasts the uplink ranging (or random access) information so that MSs attempting network entry can decode such information and use it for transmitting uplink ranging (random access).

Since different types of control signaling, e.g. system configuration broadcast, paging, resource allocation/control, should be sent with different periods and some event driven (e.g. no paging information has to be sent if no MS is to be paged), we propose to use the Broadcast Pointer Channel (BPCH) to signal (signal) the presence of a specific type of control information. The MS need only decode the BPCH to discover if it needs to decode subsequent controlsA channel. This achieves power saving. To further reduce overhead, the BPCH may not be present in every frame. We propose two options for the MS to detect the presence of BPCH. One option is for the MS to perform blind detection of the presence of BPCH. The second option is to indicate the presence of a BPCH by a flag in the multicast control segment (MCCS), which is a segment already present in each frame for resource allocation/control purposes.

Since it is important for the MS to receive the system configuration information transmitted by the BS, we propose a scheme that enables the MS to track whether it has the latest system configuration information transmitted by the BS. The proposed scheme also enables power saving of the MS in the normal mode, the sleep mode, and the idle mode.

Based on the above listed sections, we propose an overall MS network entry procedure.

For the multi-carrier deployment scenario, the BS instructs the broadband MS to monitor a subset of carriers for control information, power saving purposes, reduce processing requirements, and reduce system control signaling overhead. We propose primary and secondary carriers carrying different types of control information.

Introduction to the design reside in

This document introduces the types of control information required for 802.16m system operation, including system access, transmission/reception of traffic packets, handover, and the like.

Different types of control information have different characteristics in terms of changing frequency, broadcast or unicast, robustness requirements, importance for initial system access, and so on. Therefore, different types of control information should be treated differently.

This document describes how each type of control information should be transmitted by the BS and received by the MS. A description of the MS network entry procedure and sleep mode operation is provided in terms of how the MS obtains the necessary control information for proper operation. Support for multi-carrier operation is also described in terms of how the MS monitors each carrier for the necessary control information.

Control information in legacy 16e systems

In 16e, scheduling control information is transmitted in the MAP, and system information is transmitted in the DCD/UCD. Also, neighbor BS information and paging information are transmitted in a broadcast MAC message.

Some of the information sent on the MAP need not be dynamic and therefore may be sent in a less frequent manner to reduce overhead.

● e.g. STC zone transition IE, ranging zone definition, fast feedback zone definition.

Some of the information in the DCD/UCD is static system information and thus does not need to be periodically broadcast to MSs that have entered the network or broadcast for a relatively long period of time to improve reliability.

● e.g. BS ID, operator ID, subnet ID, TDD ratio.

Some of the information in the DCD/UCD is semi-static system configuration information, and thus does not need to be periodically broadcast to MSs that have entered the network or broadcast for a relatively long period of time to improve reliability if the configuration has not changed.

● e.g. burst properties, handover parameters.

Also, the neighbor BS information is semi-static information, and does not need to be periodically broadcast to the MS that has entered the network if the configuration has not changed.

Type of DL control information (1/3)

Type of DL control information (2/3)

Type of DL control information (3/3)

Broadcast Pointer Channel (BPCH) (1/3)

The broadcast of information types (1) (3) (4) (5) (6) may or may not exist at sub-frame or super-frame boundaries. To efficiently indicate the presence/absence of these information blocks, a 16m Broadcast Pointer Channel (BPCH) was introduced.

The 16m BPCH contains the following:

● information Block Presence flag

● length of each information block present

Examples of information blocks are:

● type of system information (1) (3) (4) (5). In this information block, a plurality of MAC management messages for different information types may be encapsulated.

● paging information (type (6)) (either quick paging or full paging information)

The benefit of the 16m BPCH is to allow the sleep mode and idle mode MSs to decode only the 16m BPCH to find out whether broadcast information is present and whether the present broadcast information is relevant (e.g., paging information is not relevant for the sleep mode MSs).

● if the broadcast information is not present or not relevant, the MS may go back to sleep without decoding the remaining part of the subframe and the resource allocation/control information, i.e., type (7).

● if the broadcast information is present and relevant, the MS need only decode the relevant broadcast information and go back to sleep without decoding the remainder of the subframe and the resource allocation/control information, i.e., type (7).

Broadcast Pointer Channel (BPCH) (2/3)

The BPCH may or may not be present in each subframe. There are two options how the presence of BPCH can be detected.

Option 1: a 'BPCH presence' flag is added to a multicast control segment (MCCS) to indicate the presence/absence of BPCH. It should be noted that the MCCS contains control information to indicate that resources in a frame are divided for a traffic burst. The MCCS has a fixed length and modulation/coding (see document NNN for details).

● the MS first decodes the MCCS. If the 'BPCH present' flag is set to '1' (i.e., BPCH is present), the MS will decode the BPCH. The length and modulation/coding of the BPCH is fixed. The information contained in the BPCH will allow the MS to decode subsequent system broadcast information. The remaining resources in the subframe are used for traffic bursts and the division of these resources is signaled by the MCCS.

● if the 'BPCH present' flag is set to '0' (i.e., no BPCH is present), the MS will know that BPCH and system broadcast information are not present. The remaining resources in the subframe are used for traffic bursts and the division of these resources is signaled by the MCCS.

Broadcast Pointer Channel (BPCH) (3/3)

Option 2: if so, the BPCH is located at a fixed position in the subframe. It has a fixed length and modulation/coding. The MS performs blind detection to determine whether BPCH is present.

● the MS first attempts to decode the BPCH. If the decoding is successful, the information contained in the BPCH will allow the MS to decode subsequent system broadcast information. The remaining resources in the subframe include the MCCS and resources for traffic bursts. The partitioning of resources for traffic bursts is signaled by the MCCS. It should be noted that the MCCS has a fixed length and modulation/coding.

● if the MS did not successfully decode the BPCH, the MS will assume that the BPCH and system broadcast information are not present. The MS continues to decode the MCCS and the remaining traffic bursts, if applicable.

Transmission of System configuration information (type 4) -1/3

Since this type of information is semi-static and can change, the BS must inform the MS in time when the information changes and at the same time achieve power savings for the MS.

This is the proposed method:

● 'System Configuration Change Count (SCCC)' is included in a system configuration broadcast message transmitted from the BS. Which is used to indicate the version number of the associated system configuration information. An action timer is included in the system configuration broadcast message to indicate when the associated system configuration is in effect.

● in general, the MS stores in its memory up to two sets of SCCC values and corresponding system configuration information. One set is the currently validated SCCC value and corresponding system configuration information. Another set is the SCCC value and corresponding system configuration information that will take effect at the specified action time.

● BS periodically transmits SCCC and 'System Configuration Change Alarm (SCCA)' flags in a frequent manner. For example, each superframe is a part of superframe configuration control information, i.e., type (2).

The ● SCCC is used to indicate the version number of the system configuration information that is currently in effect. The SCCA flag is used to indicate whether the BS has broadcast system configuration information that is newer than those associated with the current SCCC.

Transmission of System configuration information (type 4) -2/3

● if the MS has previously received a corresponding system configuration broadcast message, by detecting the SCCC value, the MS knows the current version of the system configuration information in effect and can configure itself accordingly. By detecting the SCCA flag, the MS knows whether the BS has broadcast new system configuration information. If the flag is set to '1', the MS will attempt to decode the system configuration broadcast message in the current and subsequent subframes until it has successfully decoded the information.

● if the MS has detected an SCCC value from the BS that is different from the SCCC value(s) the MS has stored, the MS will stop UL transmissions and attempt to decode system configuration broadcast messages in the downlink from the BS. After the MS has successfully decoded this system configuration broadcast message containing the SCCC value, it will only recover the UL transmission.

● to support the MS to save power in normal/active mode:

● if the MS has detected that the SCCC value has not changed and the SCCA flag is set to '0', the MS need not decode the system configuration broadcast message indicated in the BPCH.

● if the MS has detected no change in the SCCC value and the SCCA flag is set to '1', and if the MS has previously successfully decoded the system configuration broadcast message with a new SCCC value, the MS need not decode the system configuration broadcast message indicated by the BPCH.

● if the MS has detected no change in the SCCC value and the SCCA flag is set to '1', and if the MS has not previously successfully decoded the system configuration broadcast message with a new SCCC value, the MS must decode the system configuration broadcast message indicated by the BPCH.

Transmission of System configuration information (type 4) -3/3

● to support an MS in sleep mode or idle mode to save power:

● BS periodically transmits system broadcast information

● the MS in sleep mode or idle mode wakes up periodically (periodically configured by the BS) to attempt to decode the SCCC/SCCA transmitted in the superframe configuration control information. The wake-up time of the MS should coincide with the time when the SCCC and SCCA are broadcast by the BS

● if the MS detects that the SCCC has changed and that the value is different from the value it stores in memory, the MS should wake up in this and subsequent subframes to decode the BPCH and system broadcast information until it successfully decodes the system configuration broadcast message from the BS containing the SCCC value.

● if the MS detects that the SCCC has not changed but the SCCA flag is set to '1' and the MS has not previously received a system configuration broadcast message from the BS containing a new SCCC value, the MS should wake up in this and subsequent subframes to decode the BPCH and system broadcast information until it successfully decodes the system configuration broadcast message from the BS containing the new SCCC value.

● if the MS detects no change in SCCC and the SCCA flag is set to '0', the MS can go back to sleep (if it is within the sleep window or paging unavailable period) without decoding subsequent subframes.

Initial network entry procedure at MS (1/2)

There are two methods for the MS network entry procedure, which correspond to the two options of type (1) shown in slide 3.

Method 1 is based on option (1 a) of type (1) information:

● step 1: MS and synchronization channel/preamble synchronization

● step 2: MS decoding information type (1)

● step 3: MS decoding information type (2)

● step 4: the MS performs the UL ranging procedure based on the ranging region information given in the information type (2)

● step 5: the MS obtains type (3) and type (4) information through unicast signaling from the BS transmitted on the DL PHY subframe

Initial network entry procedure at MS (2/2)

Method 2 option (1 b) based on type (1) information:

● step 1: MS and synchronization channel/preamble synchronization

● step 2: the MS decodes the information type (2) and obtains ranging region information

● step 3: the MS performs the UL ranging procedure based on the ranging region information given in the information type (2)

● step 4: the BS detects the MS ranging attempt and the BS transmits information type (1). MS decoding information type (1)

● step 5: MS continues the ranging procedure

● step 6: the MS obtains type (3) and type (4) information through unicast signaling from the BS transmitted on the DL PHY frame

Multi-carrier support (1/3)

In the contiguous spectrum case, the multi-carrier mode is used to support MSs with different bandwidth capabilities. For example, a 10MHz spectrum may be divided into two 5MHz carriers to support both 5MHz and 10MHz bandwidth capable MSs.

Not all carriers need to carry all system broadcast information because system-wide and sector-wide system information is common to all carriers. Repeating the information over multiple carriers increases overhead.

Two types of carriers can be defined:

● primary carrier: this is the carrier carrying the synchronization channel (or preamble), all system information, neighbor BS information, paging information, and resource allocation/control information, i.e., information types (1) through (7) described in slides 3-5

● secondary carrier: it is a subset carrying system information, i.e. information type (2), for information related to the superframe configuration on the carrier; and resource allocation/control information for each subframe within the carrier, i.e., a type (7) carrier. This type of carrier may also carry a synchronization channel (or preamble).

Multi-carrier support (2/3)

One or more carriers in the spectrum may be designated as primary carriers. One or more carriers in the spectrum may be designated as secondary carriers.

Narrowband MSs, i.e., MSs with bandwidth capability to transmit/receive on only one carrier at a time, are assigned to the primary carrier.

A wideband MS, i.e., an MS with bandwidth capability to transmit/receive on multiple carriers at a time, is assigned to one or more primary carriers.

The broadband MS monitors only the assigned carrier(s) for system broadcast information, type (1) through type (6), and resource allocation/control information for new traffic packet transmission, type (7). The broadband MS also monitors the superframe configuration broadcast information, i.e., the secondary carrier(s) of type (2), for at the superframe boundary. The MS may monitor the resource allocation/control information, i.e. type (7), on the secondary carrier(s) used for HARQ retransmissions. Specific details of HARQ ACK/NAK and retransmission for multi-carrier operation are given in other annexes.

Multi-carrier support (3/3)

The broadband MS may be configured by the BS to feed back Channel Quality Information (CQI) for one or more carriers. When configured to feed back the CQI of a secondary carrier, the MS must measure the channel on the corresponding carrier through a preamble or pilot signal transmitted on that carrier.

Key technology

Method for a BS to determine when to transmit static system-wide information for an MS entering a network in an event-triggered manner.

Method for a BS to transmit information related to uplink initial random access or initial ranging resources to an MS before the MS enters a network

Method for indicating presence/absence of specific system broadcast information by BS

Method for synchronizing BS and MS on system configuration information

Method for MS to perform initial network entry

Method for transmitting various types of control information over multiple carriers

Proposal for IEEE802.16m resource allocation and control

Range of

● this document proposes an ieee802.16m resource allocation and control design for single band operation

● describes in a separate document (C802.16m-08 _178, also included in other accessories) a resource allocation and control design for multi-band operation.

Background

● conventional 16e systems use a two-dimensional approach to assigning resources to users. This requires a lot of overhead to signal the assigned resources.

● other systems, such as LTE and UMB, use a one-dimensional approach based on a channel tree to reduce resource assignment signaling overhead.

-each assigned user is allocated resources by assigning a node from the tree.

Although channel trees may save signaling overhead, there are some limitations on the number of base nodes that can be assigned.

For example, if a binary tree is used, only 2, 4, 8, 16, etc. number of nodes may be assigned. Furthermore, if more granularity is added to the tree, the total number of nodes increases, which increases the number of bits required to signal each assignment.

● the conventional 16e system is also inefficient in power because it relies on broadcast and/or multicast assignment information.

UMB and LTE systems both have lower power overhead, since the assignment information is transmitted using separate unicast messages, which are power controlled separately for each user.

● conventional 16e systems use a TDM approach for multiplexing control and data in sub-frames.

Since the assignment information is located in the same region of the subframe in all sectors and since this information is a multicast message, power boosting may not be employed.

Background (2/3)

Background (3/3)

Request from SRD

● overhead

To the extent feasible, the overhead for all applications, including overhead for control signaling and overhead related to bearer data transfer, should be reduced without compromising overall performance and ensuring proper support for system features.

Motive machine

● in order to improve the overhead of the control channel of legacy systems and make it better than existing systems such as UMB, LTE, a new control channel design is proposed for ieee802.16m subframes.

● the control and traffic channels are confined in each subframe and span all symbols within the subframe.

● an extended subframe may be defined to connect the subchannel resources across multiple subframes to reduce control overhead and improve UL coverage. This is for FFS.

● the control channel contains a short multicast message and a separate unicast message for each assignment.

The multicast message remains small because its power is controlled by the lowest geometry user, which is assigned in a given sub-frame.

-each unicast message power is controlled by a predetermined user.

-group assignment message for VoIP. The contents of this set of assignment messages are described in another document, C80216m-08_177, also included in other attachments.

The ● multicast message is a 10-bit message that indicates how the available resources are partitioned. The partitions are not associated with any channelization tree and therefore there is no limit to the number of resources that can be assigned to a mobile station.

● the multicast message also eliminates the need to signal the node ID for each assignment. This results in a significant reduction in overhead since most channelized trees use 9-11 bits for signaling node IDs. The reduction in overhead increases as the number of assignments increases.

Overview of control channel framework (1/2)

● the bandwidth may be divided into one or more regions, which may be diversity regions or local regions. Each zone contains an integer number of Basic Channel Units (BCUs) (see document C80216m-08_175, also included in other annexes).

● independent control channels are defined within each zone to assign resources in that zone.

● the multicast control segment plus other DL control channels (e.g., HARQ ACK, power control bits) contain integer multiples of BCUs.

● the diversity region may include a persistent sub-region and a non-persistent sub-region. The local region comprises only non-persistent sub-regions.

● the multicast control segment indicates how the available resources are divided.

This includes resources that are not used in the persistent sub-region as well as in the non-persistent sub-region.

The multicast control segment of the zone contains the Combination Index (CI) and if persistent resources are allocated it contains the Resource Availability Bitmap (RAB) (see VoIP document C80216m-08_177 also included in other attachments).

-for the local area, the multicast control segment comprises a Permutation Index (PI).

● the multicast control segment power is controlled by the lowest geometric user assigned in the sub-frame.

● the multicast control segment is sent in the diversity region along with other multicast and broadcast channels.

Overview of control channel framework (2/2)

Content of multicast control segments for a diversity zone

● the multicast control segment contains a 10-bit combination index.

● the index is an index to a lookup table that contains a size n₁,n₂,…n_kAll possible combinations of the ordered lists of k partitions, where Σ n_i= N, i =1,2, …, k. The partitions in each list are sorted by increasing size.

● to reduce the size of the combined index, a fixed maximum number of assignments is assumed. The maximum number of assignments depends on the number of available resources. If more assignments are needed, the second combined index is used to further partition the resources.

Combined index lookup table

● the combination index lookup table depends on the amount of available resources.

● the table below shows the number of users that can be assigned with one combination index (10 bits) for a given number of available resources.

● use various combination indices for bandwidths containing more than 24 BCUs.

Examples of Using combinatorial indices

● for example, if there are 24 BCUs and 4 mobile stations in total, the arrangement is as follows:

-MS 1: 6 units

-MS 2: 4 units of

-MS 3: 10 units

-MS 4: 4 units of

● the combination index corresponding to CI (4, 4,6, 10) is signaled on the multicast control channel.

● the maximum number of assignments of one combination index with 10 bits is 8. Another combinatorial index is used to partition the last partition in the previous combinatorial index if more than 8 assignments are needed.

● for example, to assign 9 users using the combined index of the corresponding CI (1, 1,1,2,2,3,4,4, 6), two combined indexes may be used.

-the first combined index corresponds to 24 available resources CI₂₄8 divisions of (1, 1,1,2,2,3,4, 10).

-the second combined index corresponds to a CI₁₀(4, 6) which divides the last division in the previous CI (10 resource units).

Content of multicast control segment for local area

● for local channel assignment, a Permutation Index (PI) may be used instead of a combination index to indicate the subbands assigned to different users.

● the permutation index represents the number of consecutive subbands assigned to each user. Non-contiguous subbands are assigned to the mobile station using an independent assignment message.

● the mobile stations are assigned in the order of their assigned sub-bands.

● if the assigned number is k and the total number of subbands is N_SThen the permutation index represents the vector (n)₁,n₂,…,n_k) Where Σ n_i=N_SAnd n is_i>0，i=1,2,…,k。

● for example, if the permutation index represents vector (n)₁,n₂,n₃) The first mobile station is then assigned the first n₁Sub-band, second mobile station is assigned next n₂Sub-band, and the third mobile station is assigned the next n₃Sub-bands.

● if the number of subbands is 8 and the maximum assigned number is 8, then the number of permutations is 128 (7 bits).

● in general, if there are N subbands with up to N assignments, then the number of permutations is 2^N-1Thus requiring N-1 bits for the permutation index.

Examples Using permuted indices

● the following table shows an example of a permuted index look-up table for the case where there are 4 sub-bands.

● in this case, there are a total of 8 permutations and only 3 bits are needed to signal the PI.

Non-persistent resource assignment in diversity regions

● the ordered list of available resources within the persistent and non-persistent sub-regions is partitioned into several segments.

● the segments are sorted with increasing partition size.

● different types of segments include:

-a UL control section for controlling the transmission of data,

-a DL unicast control and traffic segment,

DL retransmission control and traffic segments in case of resource-adaptive synchronous HARQ (for asynchrony this segment does not exist, since asynchronous HARQ retransmissions can be assigned by unicast control and traffic segments),

DL group control and traffic segment.

● is signaled using a combinatorial index that indicates how the N resources are divided into 5 partitions, each of length N₀,n₁,n₂,n3,n4。

Unicast control and traffic segment

● unicast control and traffic division comprises a unicast assignment. There may be multiple unicast control and traffic segments.

● the unicast message is scrambled by the user ID of the intended user.

● the length of the message depends on the type of assignment. There are a limited number of message lengths (e.g., 2). The mobile station decodes the message using blind detection.

● each unicast message is followed by data for the intended user.

● the length of the unicast message may be part of the BCU.

Group control and traffic segment

● sets of control and traffic segments are used for real-time services such as VoIP. There may be multiple group assignment segments (see VoIP document C80216m-08_177, also included in other accessories, for details).

● the control channel used for the group assignment segment is a multicast assignment message and is located within the resources allocated for the group assignment segment.

● to identify the group assignment segment, the group assignment message is scrambled by a group ID.

● the message length is known to all mobile stations in the group.

UL control segment

● use the UL CI to assign resources to multiple users. And then follows the unicast assignment information for each user.

● the unicast information is of fixed length and is decoded sequentially by each user until the mobile station finds its UL unicast assignment message.

● the unicast information contains the assigned MCS and it is scrambled by the user ID of the intended user.

● the group UL assignment message is signaled after a unicast UL assignment. The group assignment message is an integer multiple of the unicast message length and it is scrambled by the group ID (see VoIP document C80216m-08_177, also among other attachments).

Retransmission segment

● retransmission segments are only needed when the resource is used to adapt synchronous HARQ.

● in resource adaptive synchronous HARQ, the retransmission occurs at a predetermined time and at the same MCS as the original transmission.

● only the resource location is adapted.

● the retransmission segment is partitioned using a combination index that is signaled at the beginning of the retransmission segment.

● the retransmission combination index is scrambled by a unique code that identifies the retransmitted segment.

● retransmissions of a CI are followed by unicast messages for each retransmission. The unicast message contains the resource ID of the transmission on the previous interface.

Persistent resource assignment

● persistent resource assignments may be for low geometry users of services such as VOIP.

● the persistent sub-region allows for multiplexing of persistent resources and non-persistent assignments via the RAB.

● details of persistent sub-regions and RABs are given in VoIP document C80216m-08_ 177.

Resource allocation within a local zone

● local areas may use dedicated pilots or common pilots (see document C80216m-08_172 included in other annexes).

Dedicated pilots may be used when performing pre-coding.

● in both cases, the PI is used to indicate how the sub-bands are allocated to different users.

● the multicast control segment containing the PI is sent in the diversity region.

Other multicast and broadcast messages requiring frequency diversity are transmitted in the diversity zone.

● the user specific resource assignment is signaled in the resource allocated to the user.

This improves the robustness of the control channel, since the control channel will be located in the best sub-band of the mobile station.

In case where dedicated pilots are used for beamforming, the control channel is also precoded using the same preferred precoding vector as the data, which further improves the control channel.

The MCS and power allocated to the control may be different from the data.

Control channel overhead comparison

● comparison of control channel overhead with WiMAX reference system and UMB in two cases

-case 1: simple non-MIMO assignments (e.g., STTD R1/R2)

Case 2: single user MCW MIMO assignment with 4 layers

● only include the overhead due to resource allocation. Other control overhead such as the DLACK channel and the power control channel are not included in the overhead calculation.

● assumptions for WiMAX reference System overhead calculation

-FCH is modeled

Transmit the map using QPSK1/2, repetition = 6. The three subpictures were transmitted using QPSK1/2, with repetition =4, 2 and 1.

The user assignments for the graph and the 3 sub-graphs are 0.07,0.20,28,0.45, respectively.

● assumptions for UMB overhead computation

Unicast messages in F-SCCH are 39 bits long (including CRC).

One F-SCCH message is needed for each assignment in case 1.

Two F-SCCH messages are needed for each assignment in case 2.

-transmitting the F-SCCH using QPSK 1/3.

Control channel overhead comparison

● assumptions for Nortel overhead calculations

Multicast control segment containing 10-bit combinatorial index and 6-bit CRC

non-MIMO assignment in case 1 is 22 bits including CRC.

MIMO assignment in case 2 is 38 bits including CRC.

Multicast control segments are transmitted using QPSK1/3, repetition =2 and unicast messages are transmitted using QPSK 1/3.

There are 24 BCUs in 10 MHz. One BCU is used to carry CI and DL ACK channels and other DL control channels. There are 23 available BCUs for DL assignment.

Control channel overhead comparison

Comparison of blind decoding complexity

● in LTE, the number of blind decoding attempts as provided in the document R1-081101

-for a common search space is-10

-30 for the UE-specific search space

A total of 40 blind decoding attempts per TTI, which equals 2 Mbps.

● number of blind decoding attempts in the Nortel proposal

Up to 2 attempts per partition for different unicast message types

-total number of blind decoding attempts <20< LTE due to expected number of partitions < 10.

Summary of the invention

● in summary, the proposed control channel design shows a significant improvement in control overhead over the WiMAX reference system as well as the UMB.

● the new design minimizes power and bandwidth overhead.

● the lower overhead is due to the following reasons:

using combinatorial indices instead of channelisation trees

● greater flexibility (not limiting the number of resources that can be assigned)

●, because the node ID does not have to be signaled in every assignment.

-using multicast control and unicast control

● multicast control is used to signal the common information needed for all assigned users, an

● unicast control is used to signal user specific information

By combining unicast control and data, the resource granularity for control is lower.

● for unicast control, the granularity is a unit to a single tone

● for group control, granularity is a unit to RB

● this new design also allows for achieving microsleep by first ordering the tones in frequency and then assigning the tones to the control channel at the beginning of the allocated resources.

Proposal for IEEE802.16m DL resource blocks and channelization

Range of

● this document proposes a new resource block structure and channelization for ieee802.16 m.

● Pilot design and resource allocation and control are given in separate literature (see C802.16m-08172 and C802.16m-08176, which are also included in other accessories).

Motive machine

● conventional 16e systems use a TDM approach to configure diversity, local and MIMO zones.

● in the FDM method, channelization may span all symbols in a subframe. Different zones are configured to use different portions of the frequency band.

-making the channelization across all symbols allows for efficient power control of both control and traffic.

Overview of channelization design

● define new channelization and control channel designs for IEEE802.16m subframes

● channelization for control and traffic is confined to each subframe and spans all symbols within the subframe.

● extended subframes may be defined to connect subchannel resources across multiple subframes to reduce control overhead and improve UL coverage. This is for FFS.

Channelization (1/2)

● in a 16m subframe, the bandwidth is divided into one or more regions. Each zone contains a set of physical tones. The set of physical tones belonging to a zone may be contiguous or non-contiguous.

● the zone is used for

-diversity channel assignment

Frequency selective scheduling (local area)

Fractional Frequency Reuse (FFR)

Single Frequency Network (SFN) transmission

● the frequency hopping pattern is always confined to one zone.

For SFN transmission, the hopping pattern is the same as in the corresponding zone in each sector involved in SFN transmission.

For FFR, the hopping pattern is different for different sectors.

Channelization (2/2)

● each zone has a one-dimensional ordered list of resources, the unit being a Basic Channel Unit (BCU).

● BCU

The BCU contains 3 Resource Blocks (RBs), where an RB is 12 tones and 6 OFDM symbols. Details of RB definition and pilot design are described in the independent literature (see C80216m-08_ 172).

For a 10MHz system, there are 24 BCUs.

In the local region, the BCU is formed of consecutive physical tones.

In the diversity zone, the BCUs are formed by physical tones spread over the whole zone.

Each BCU spans all OFDM symbols in the subframe.

The unit of resource partitioning between local and diversity regions is BCU.

● defining a BCU size of 3 RBs has the following benefits:

this BCU size is sufficient size for proper channel estimation using common pilots.

This RB size provides sufficient granularity and flexibility for VoIP assignments (see c802.16m-08_ 177).

For group assignments, such as VoIP, groups are allocated in BCU units, while individual VoIP users can allocate resources in RB units.

For non-VoIP assignments, the resource units need not be granular.

● the resources are assigned using a combination of multicast messages and separate unicast messages for each assignment. Details of the control channel are described in a separate document (see control channel document C80216m-08_ 176).

Mapping of physical to logical resources of a partition

Channelization procedure

● step 1: the sub-carriers within the band are divided in units of physical BCU, i.e., 36 tones, between the local area and the diversity area. The physical tones within the band are assigned to each zone by first assigning contiguous tones (in units of BCUs) to the local zones and evenly distributing the remaining tones for the assigned zones. The physical tone assignment to each zone may be hopped from time to time, e.g., symbol to symbol or symbol set to symbol set, frame by frame, and so forth.

● step 2: once the zone is made up of a set of physical tones, the physical tones are permuted using sector and zone specific permutation to map to logical tones.

● step 3: an ordered list of RBs is then formed for each region, where each RB contains a set of logical tones. The BCU is formed by grouping 3 RBs.

Channelizing program (optional)

● are in-band, if the diversity region size is one or two BCUs, the RBs used to form the BCUs may be distributed in-band. This improves the diversity order of the logical BCUs.

● to improve channel estimation in each of the disjoint diversity RBs, a high density of pilot patterns should be used in those RBs.

Zone configuration

● the following figure shows how different zones can be configured in one subframe.

● contain separate control channels within each zone.

● the control channel spans all OFDM symbols.

● the FFR zone may be a diversity or local zone.

Channelization for multiple carriers

● there are two options in multicarrier operation.

● in option 1, each carrier may have different channelization depending on the number of zones configured.

In this case, each carrier will have an independent control channel.

● in option 2, channelization may span multiple frequency bands.

This case is used for transmission to broadband users.

In this case, a single control channel may be used.

Proposal for IEEE802.16m VoIP control channel

Range of

● this document proposes a control channel signaling design for VoIP that supports real-time services such as ieee802.16 m.

This document can be used in conjunction with the control channel signaling design [ control document ] to form a complete 802.16m control channel design.

Introduction to the design reside in

● real-time service support is a basic feature of 16m systems. Such services may include:

-VoIP

-games

-video telephony

● these services are characterized by delay sensitive data requirements, small throughput, and a relatively large number of users.

● SRD requirements necessitate efficient control channel signaling design with the ability to accommodate a large number of users.

Efficient multiplexing of users on UL and DL is essential to guarantee high capacity for such traffic.

-16m VoIP SRD requirement:

● 1.5.5 x reference System Capacity

● 30 users/MHz/sector

● the control channel design for real-time services may be different from those for packet data, but must be able to be used simultaneously to support mixed traffic scenarios.

Background (1/2)

● due to the relatively large number of simultaneous VoIP users, it is necessary to design a 16m control channel structure for VoIP so that the overhead per HARQ transmission assignment must be kept on the order of a few bits. Furthermore, many transmission parameters such as packet and modulation schemes are common to all VoIP users and therefore do not need to be signaled.

● explicit signaling with conventional unicast control signaling is used for data packet transmission, while general power efficiency may be prohibitive due to the large overhead associated with additional transmission parameters (not necessary for VOIP).

● the broadcast method may remove many of these public domains but suffers from inefficient transmissions to both cell edges and high geometry users.

● the current approach in 802.16e does not have specific signaling to support VoIP, and as a result the signaling overhead is large. This allows for maximum flexibility and specification of VoIP packet allocation, which is however capacity limited. This is due to the large broadcast fixed overhead, and the considerable signaling overhead per HARQ transmission.

Conventional 16e systems may use subgraphs to target some geometry groups separately, however there are overhead constraints even if subgraphs are used.

For a 1x2ieee802.16e system, where 140 users per link and DL overhead [ reference ] of 10% retransmission rate:

● MAP overhead: 230 time slots (64%)

● use 3 subgraphs: 144 time slots (40%)

Background (2/2)

● multicast methods, such as the group signaling method specified for 3GPP2UMB systems, are useful in that the number of bits per assignment is relatively small, while the use of multiple groups allows for improved power efficiency for different geometries.

Efficient reuse of group resources is needed to maintain this power efficiency.

● in some cases, it may be desirable to assign modifiers to enhance system characteristics or reduce assumptions in the blind detection of transmissions.

However in many cases such modifiers are useful for group assignment, the number of groups assigned is unknown prior to bitmap reception and ultimately requires a significant number of bit fills in order to use these fields.

Advising

● this document presents a group-based control channel framework for VoIP and real-time services. The present proposal combines the efficiency and flexibility of unicast assignments by maintaining small groups and adding assignment modifiers, and also reduces control overhead and messages by using group-based assignments.

● the group signaling method can be integrated with a dynamic resource partitioning framework control channel literature to provide efficient multiplexing of different multicast groups and data packet services.

The assignment modifier can also be added to the group signaling with minimal field padding in this proposal.

Proposal for 16m

● group-based assignment (bit map)

-allowing efficient signalling to many VoIP users simultaneously

-signaling non-persistent assignment/transmission only

-assigning modifiers to allow for increased transmission specifications

● persistent allocation

-predefining resources for specific VoIP transmissions or assignments to reduce signaling

-occupied resources indicated by a Resource Availability Bitmap (RAB)

● multiplexing group resources obtained by resource division

Flexible group resource assignment size and multiplexing by signaling partition size

Assuming that the detection group bitmap allows flexibility in group partition positions.

Non-persistent group assignment (1/2)

● group assignments are used to benefit a large number of users

-groups are signaled by a group bitmap.

Each position in the bitmap is assigned to a user. The value of the bit for each user indicates whether the user is assigned a resource ('1') or a resource ('0').

-the assignment of the first indication is assigned to the first available resource(s) and the assignment of the second indication is assigned to the second available resource(s).

Each group bitmap has its own set of resources (i.e. different resource segments).

Non-persistent group assignment (2/2)

● increase flexibility by assuming a detection group bitmap

For DL assignments, the user will attempt to use its group ID to decode the start of each resource segment, thereby attempting to find its group resource assignment.

For UL assignments, the user will attempt to use its group ID to decode each possible location of the control message in the UL assignment control segment, thereby attempting to find its group resource assignment.

-allowing transmission of bitmaps when needed at 16m minislots and different resource locations

● easy reuse of group resources facilitates the use of many groups

-groups based on service level

● some services require frequent transmissions (VoIP) and others are less frequent

-geometry-based groups

● power efficiency

To reduce signaling, groups may also have the same properties (useful for VoIP):

● MIMO mode

● resource allocation size

●MCS

-if no users in the group require an assignment, a specific group assignment bitmap can be omitted

● assigning users to groups via group configuration messages

-the message indicates the bitmap size, the included bit field and the attributes

Supporting features for group assignment

Assignment related field

-each field is linked to the indicated number of bitmap assignments, which can be derived from the partition size.

Thus each user can dynamically determine the field/index size

● Supplemental Transmission Information Field (STIF)

Up to 2 bits to indicate new packet transmission, number of packets or packet start position

● resource permutation index:

-indexing a table linked to possible resource allocation sizes to indicate assignments in a bitmap

-allowing dynamic resource size for bitmap allocation

● user group index

-scrambling the index of the indicated assignment. Can create "pairs" or groups of users

● can be used to assign particular resources to particular users

● may be used for MIMO applications

Group related field

● UL resource/partition index

-indicating the resource partitioning assigned to the group bitmap

Multiple groups can be assigned to the same partition

Supplementary Transmission Information Field (STIF)

● indicate one (or more) of the following:

-new packet calibration (toggle) (NPT) (multi-state calibration)

-in case of ACK/NAK errors, preventing ambiguity of transmission to the user, since it changes value each time a new packet is started

-multi-packet (MP)

Allowing the BS to specify the delivery of 2 packets to a user, also indicating to the other users in the group: this assignment will use the resources twice

-Packet Start Frame (PSF) in superframe

-indicating a frame within the superframe on which the first HARQ packet transmission occurs. This indication simplifies the detection of hypotheses in the presence of control signaling errors.

Sub-packet HARQ Transmission index (SPID)

-indicating the sub-packet ID in the HARQ transmission. Time-slot asynchronous IR HARQ packet transmission.

● configure the pattern for each group bitmap

-can also be configured as a one-bit field (2-state) for 1-mode, or a 2-bit field (4-state), which can be configured to support one or more of the above-mentioned modes

Resource permutation index

● this field may exist and may be used to assign different amounts of resources to a given group of users

For a certain number of resources within the group assignment segment, a table may be created to indicate the possible resource partitioning to the different users within the group.

This field signals the index associated with the resource partition of the group assignment.

For example, for the case of 4 resource partition sizes, a table may be created that may be linked to the index.

● if the group is configured to use this field, the user can determine that a 3-bit field is appended to the bitmap by recording the partition size and the minimum resource partition size. The size of the index is dynamically flexible and is associated with the partition size.

Reordering user group indices, or creating user groups within a bitmap

● this field indicates an index corresponding to a combination of pairs or groups of assigned users.

The users with the indicated assignments are combined into pairs, triplets, quadruplets, etc.,

this allows selected multiple users to be assigned to the same resource

Without this index, users are paired in the order of bitmap positions.

● a table of possible pairs or groups of users may be created for a plurality of indicated assignments.

● example:

-bit field "01" indicating that assignments 1 and 3 are paired on a first resource and assignments 2 and 4 are paired on a second resource

Thus, UE12 and UE46 are paired on the first resource, and UE30 and UE24 are paired on the second resource.

UL resource/partition index

Bit field on a resource-directed UL control message

● assignment group bitmap message is appended with a bit field specifying the UL partition number used for assignment

● multiple bitmaps may be assigned to the same partition

● multiple groups may be assigned to the same partition to support cooperative space division multiplexing (CSM)

● having an indicated group assignment of assigned resources greater than the partition size, starting at the end of the partition and allocating resources, spanning the partition to the beginning, and then continuing again from the end of the partition.

-the mobile station can derive from the bitmap the total number of resources assigned to the group and compare with the indicated resource partition size

Method allowing efficient packing of group assignments of different sizes

● user sorting index may also be used to assign users in a particular order

For a plurality of indicated assignments, a table of possible orderings of users may be created.

The user ordering index may also be used to "shuffle" the assignment of one or more group bitmaps to allow further control of which users are grouped together for optimization

-indexes are appended to the high geometry bitmap to minimize overhead

● to allow field size to be derived, the index applies to only one CSM layer

-the ranking index is a special case of a user group index, where the user group size is equal to 1

Persistent resource assignment

● persistent resource assignments can be for low geometry users

Persistent assignment after initial configuration does not require control signals

-all HARQ transmissions are sent on a persistent assignment that occurs periodically

● persistent sub-region allows multiplexing of persistent resources and non-persistent assignments

A resource availability bitmap is used to indicate which specific resources are available in the partition within the persistent sub-area.

● also supports persistent assignments for first HARQ transmissions or retransmissions

-persistent resources for the first HARQ transmission are configured in the initial assignment, retransmissions are non-persistently signaled by the group assignment.

● assignment/deassignment via unicast control messages

Overview of VoIP control channels in a resource partitioning framework

● the VoIP transmission may be a persistent assignment signaled in a particular resource partition, or a non-persistent assignment

-group assignment using bitmap is used for non-persistent VoIP assignment

● each group is assigned an independent resource partition

-persistent assignments are indicated to other users by a Resource Availability Bitmap (RAB)

● identification and partitioning of available resources is indicated by a multicast control segment (MCCS)

The zone partitions are signaled by a Combination Index (CI), which signals the resource partitioning in persistent and non-persistent zones.

● CIs are concatenated together and encoded using a Resource Availability Bitmap (RAB) that indicates available resources in the persistent sub-region.

RAB is a bitmap indicating which resources are available and which are occupied by persistent HARQ transmissions.

● persistent resources that are not used due to packet arrival jitter, silence state, or early termination of HARQ transmissions are shown as being available

● the resource partition indicated by the CI partitions the remainder of the resource set after the resources indicated as occupied by the RAB are removed from the resource list.

The size of the persistent region is carried in the secondary broadcast channel

Resource map-DL + UL assignment

MCCS = multicast control segment

CI = Combined index

RAB = resource availability bitmap

UCTS = unicast control and traffic segment

U = unicast assignment message

GCTS = group control and traffic segment

G = group assignment message

UL CS = uplink control segment

● the available resources assigned per group are indicated by a separate resource partition per microframe.

-resources for different groups are dynamically multiplexed.

A Resource Availability Bitmap (RAB) may also be used to indicate which specific resources are available within the partition.

Resource map-UL control segment

CI = Combined index

RAB = resource availability bitmap

U = unicast assignment message

G = group assignment message

● the UL assignment block is located within the DL resource partition.

-the partitioning comprises CI, RAB, and unicast/group assignment

● Combined index indicates resource partitioning on uplink

The RAB indicates the "in use" resources, as well as the available resources, by a persistent assignment.

-the resource partitioning specified in the CI does not include resources indicated as "in use" by the RAB

● for group assignment messages (and unicasts):

-the assignment message is appended with a bit field specifying the UL division number for the assignment

Multiple groups can be assigned to the same partition to support Cooperative Spatial Multiplexing (CSM)

Unicast messages preceding group messages in order to facilitate ACK/NAK operations

-the group message length is set to a multiple of the unicast length

VOIP packet size

● resource block size 72 (12 x 6) bits as discussed in the pilot/RB document provides flexibility in code rate for assignments. This RB size may be assigned in units of 3 RB.

●DL：

-2 transmit antennas- >6% pilot overhead

320 bit VoIP packet size (AMR full rate)

● 2 options for QPSK resource size

-3RB = first transmission code rate 0.788

-4RB = first transmission code rate 0.59

256 bit VoIP packet size (EVRC full rate)

● 2 options for resource size for QPSK

-3RB = first transmission code rate 0.67

Assignment overhead comparison (including CI)

● Total overhead for UL + DL resources (48.6 OFDM symbols) in TDD frame (1: 1) partitioning

● estimates assume full power transmission such that BW overhead is approximately equal to power overhead

MCS, QPSK Rate 1/2, repetition 1,2, 4 and 6, for all schemes (WiMAXturbo encoder curve)

The overhead does not include any padding or

12x6RB size, 3 RBs per assignment

● UL overhead is assumed to be the same as DL overhead

● 16m group assignment entry assumes:

user is partitioned into 16 bitmaps

● 4 interleaved bitmap-based, each having 4 geometry-based bitmaps

● the lowest level may be persistently assigned

New packet assignment modifier bit (2 bits per indicated assignment)

● every 5ms transmission opportunity

● without modifier, start frames are limited to incremental hypothesis detection

10 bits for CI

● persistent coding using RAB and 16-bit CRC

● non-persistent encoding using 8-bit CRC

● UMB group assignment entry assume:

-1 geometry level for bitmap, RAB attached to lowest geometry level bitmap

The users from the geometric level are divided into 8 bitmaps

● 4 interlace-based bitmaps, each bitmap having 2 start frames per 20ms superframe

● allowing packets to start every 10ms

Proposal for IEEE802.16m resource allocation and control for multi-carrier operation

Range of

● this document provides an ieee802.16m resource allocation and control design for multi-carrier operation

● resource allocation and control design for single carrier is provided in document c802.16m-08_ 176.

SUMMARY

● in multi-carrier operation, each carrier has its own control channel.

● the mobile station may be assigned one or more primary carriers for decoding scheduling control information (see document c802.16m-08_178 for resource allocation and control for multiple carriers).

● the mobile station reads the multicast control segment in its primary carrier and then searches each partition for its unicast assignment (see document c802.16m-08_176 for resource allocation and control).

● the unicast assignment indicates whether the data is contained on this primary carrier or another carrier.

● if the data is contained on another carrier, then the carrier and the partition number are indicated in the unicast assignment message on the primary carrier.

● data may be contained in the assigned partition of the primary carrier as well as in the indicated carrier.

Multi-carrier control

● in the following example, the mobile station is assigned carrier 1 as its primary carrier.

● the mobile station reads the combined index on the primary carrier and it uses blind detection to decode the unicast message in the second partition.

● this unicast message indicates that data is contained in the third partition of carrier 2.

● the mobile station must then decode the CI for carrier 2 to determine the location of the third partition.

Multi-carrier control

● the benefits of assigning secondary carriers are:

system information does not have to be broadcast on the secondary carrier,

no preamble is needed on the secondary carrier,

introducing secondary carriers results in reduced overhead, since the same information does not have to be transmitted on multiple carriers.

● when there is an active traffic transmission, the MS must send an ACK/NACK on the same carrier on which the traffic is sent/received.

● asynchronous retransmissions need not be transmitted on the same carrier.

Retransmissions are signaled on the primary carrier but can be scheduled on either the primary or secondary carrier.

Multi-carrier control

● for resource adaptive synchronous HARQ, there are three options for multi-carrier control

-option 1: resource adaptive synchronous retransmission on the same carrier as the original transmission (the MS must monitor the secondary carrier and its own primary carrier)

● the MS needs to perform blind decoding on a new packet (e.g., 3 message lengths) for all segments on the primary carrier

● MS needs to perform blind decoding on the retransmitted packet (1 message length) of all segments on the secondary carrier

-option 2: resource adaptive synchronous retransmission on a primary carrier (original transmission on another carrier)

● need to signal the original carrier ID (3 bits) and the resource ID in the original carrier (5 bits)

● the MS needs to perform blind decoding on both the new and retransmitted packets for all segments on the primary carrier (total 4 message lengths)

-option 3: resource adaptive synchronous retransmission on any other carrier

● need to signal the original carrier ID (3 bits), the resource ID in the original carrier (5 bits), the destination carrier ID (3 bits), and the resource ID in the destination carrier (5 bits)

● the MS needs to perform blind decoding on both the new and retransmitted packets for all segments in the primary carrier (total 4 message lengths)

Multi-carrier control

● all have the same number of blind decoding attempts.

Option 1 has the least overhead but the least flexibility.

Option 3 has the most overhead and is the most flexible. Option 3 may be implemented by asynchronous retransmission, which is more flexible.

● the conclusion is that option 1 is used for resource adaptive synchronous HARQ because:

option 2 is not flexible to adapt to CQI of different carriers.

Load balancing is a long-term operation. The assigned carriers need not be changed dynamically.

Multi-carrier control

● CQI feedback should be per carrier to keep the design systematic

-carriers for CQI measurement and feedback are configured by the BS

-the MS monitors superframe configuration control information on the primary and secondary carriers

Primary carrier is used for traffic transmission not active and does not require feedback information such as mobile stations in sleep mode and idle mode.

● in summary, the main/auxiliary ideas contribute to:

saving overhead of broadcasting system information on secondary carriers.

Saving the required number of blind detection attempts.

● MS monitors frame control from only one carrier

This reduces the number of control packets for decoding or blind detection

Claims (14)

1. A base station serving a network, comprising:

a receiver, a transmitter, and a baseband processor for facilitating wireless communication with a mobile station; and

a control system associated with the receiver, the transmitter and the baseband processor and adapted to:

determining first control information for at least one of the mobile stations;

transmitting the first control information to the at least one of the mobile stations;

transmitting a first version number corresponding to the first control information to indicate that the first control information should be used by the at least one of the mobile stations when the first control information should be used by the at least one of the mobile stations;

determining second control information for the at least one of the mobile stations to be started to be used in the future; and

second control information is transmitted to the at least one of the mobile stations and an alert flag is transmitted indicating that the second control information is being transmitted.

2. The base station of claim 1, wherein the control system is further adapted to transmit a second version number corresponding to the second control information to indicate that the second control information should be used by the at least one of the mobile stations.

3. The base station of claim 1, wherein the control system is further adapted to transmit an action time associated with the transmission of the second control information, the action time relating to when the at least one of the mobile stations should switch from using the first control information to using the second control information.

4. A mobile station, comprising:

a receiving circuit, a transmitting circuit and a baseband processor; and

a control system associated with the receive circuitry, the transmit circuitry, and the baseband processor;

wherein the receiving circuit is adapted to receive first control information for the mobile station from the base station and, when the first control information should be used by the mobile station, to receive a first version number corresponding to the first control information from the base station to indicate that the first control information should be used by the mobile station; and is

Wherein the receiving circuitry is further adapted to receive second control information for the mobile station to be used in the future and an alarm flag indicating that the second control information is being transmitted from the base station.

5. The mobile station of claim 4, wherein the receive circuitry is further adapted to receive a second version number corresponding to the second control information from the base station to indicate that the second control information should be used by the mobile station.

6. The mobile station of claim 4, wherein the receive circuitry is further adapted to receive an action time associated with the transmission of the second control information from the base station, the action time relating to when the mobile station should transition from using the first control information to using the second control information.

7. The mobile station of claim 4, wherein the control system comprises a memory, wherein the memory is adapted to store first control information that is currently valid and second control information that will be validated in the future at a specified action time.

8. A method performed by a base station, comprising:

determining first control information for at least one of the mobile stations;

transmitting the first control information to the at least one of the mobile stations;

transmitting a first version number corresponding to the first control information to indicate that the first control information should be used by the at least one of the mobile stations when the first control information should be used by the at least one of the mobile stations;

determining second control information for the at least one of the mobile stations to be started to be used in the future; and

transmitting second control information to the at least one of the mobile stations and transmitting an alert flag indicating that the second control information is being transmitted.

9. The method of claim 8, further comprising:

transmitting a second version number corresponding to the second control information to indicate that the second control information should be used by the at least one of the mobile stations.

10. The method of claim 8, further comprising:

transmitting an action time associated with the transmission of the second control information, the action time relating to when the at least one of the mobile stations should switch from using the first control information to using the second control information.

11. A method performed by a mobile station, comprising:

receiving first control information for the mobile station from a base station;

receiving a first version number corresponding to first control information from a base station to indicate that the first control information should be used by the mobile station, when the first control information should be used by the mobile station; and

second control information for the mobile station to begin use in the future and an alarm flag indicating that the second control information is being transmitted are received from a base station.

12. The method of claim 11, further comprising:

receiving a second version number corresponding to the second control information from the base station to indicate that the second control information should be used by the mobile station.

13. The method of claim 11, further comprising:

receiving an action time associated with the transmission of the second control information from the base station, the action time relating to when the mobile station should transition from using the first control information to using the second control information.

14. The method of claim 11, further comprising:

first control information that is currently valid and second control information that will take effect at a specified action time in the future are stored.