Quick Access Message for IEEE 802.16m

Document Number: IEEE C802.16m-09_905r3Date Submitted: 2009-05-04Source:

Chun-Yen Hsu, Tsung-Yu Tsai, Yi-Ting Lin, Kanchei(Ken) Loa,Jiun-Je Jian, Youn-Tai Lee, Chiu-Wen Chen E-mail: hcy@iii.org.tw, tyt@nmi.iii.org.tw Institute for Information Industry(III)

Shiann-Tsong Sheu, Chih-Cheng Yang National Central University

Whai-En Chen

National Ilan University

Yih-Guang Jan, Yang-Han Lee, Hsien-Wei Tseng, Ming-Hsueh Chuang Tamkang University (TKU)Venue: Base Contribution: N/A Re : AWD-DG comment Connection Management/QoS DG Purpose: Discussion and approval of the proposal into the IEEE 802.16m QoS AWDNotice:

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Considerations for the quick access message

• The following information must be carried in the quick access message– Identity of the requesting AMS– Identity of the QoS class that the requesting flows are mapped to, which allows

ABS to enforce the QoS policy when granting the BW request• Consequently, an aggregated BW for multiple flows that belong to the same QoS

class could be requested by a quick access message– BR content: The content of requesting BW

• Need error detection ability– ABS is unable to detect the erroneous information from a received quick

access message which is corrupted by the channel impairment or the collision (for example, two AMS transmitted identical BW REQ preamble in the same BW request tile)

• The selection of the sequence (BW REQ preamble)– In order to minimize the collision probability of the sequence, the selection of

the sequence must be “random” enough such that the probability of choosing a preamble should not depend on any attributes of the requesting entity (e.g. requesting station ID, requesting QoS ID, flow ID, etc.)

Design Principles

• The format of the quick access message consists of:– BW REQ preamble

• Uniquely maps to 4 bits information– a 3-bit QoS class of the requesting flows– a 1-bit MSB of the BR content

– The request ID (10 bits)• Maps to the STID of the requesting AMS

– Parity (1 bit)• Detects odd number of errors

– LSB of the BR content (1 bit)• The BR content is the concatenation of 1bit MSB (in BW REQ

preamble) and 1 bit LSB

STID Mapping and Error Detection

• When the ABS receives the quick access message, it first perform the parity check on the message with the parity bit. If it passes, The “request ID is extracted and maps to the corresponding STID– The mapping could be optimized as a lookup table search

• If the parity check failed or the mapped STID is not an active AMS, the ABS considers the quick access message being corrupted or collided

• Otherwise, if the ABS finds a legitimate STID, then it further verifies the legitimacy of the 4-bit information (3-bit QoS ID and 1-bit MSB of BW REQ content) extracted from the sequence (the method of extracting 4-bit information and checking for its legitimacy is described in the next page)

• This scheme requires 12-bit message size and provide additional benefit of error detection for the quick access message– Error detection by parity check with the parity bit– Error detection by checking the STID be an active AMS– Error detection by legitimacy check on the 4-bit information extracted from

the sequence

4-bit Information Extracted From The Sequence

• For each value of 4-bit information (3-bit QoS ID + 1-bit BR content), a random number (RN) generator is maintained in the ABS and the AMS in a synchronized manner

• When an AMS sends a BW REQ preamble for a given 4-bit information, the sequence is selected based on correspondent RN generator– The algorithm to generate the random number and select

the BWREQ preamble is TBD

• When an ABS receives a BW REQ preamble + STID correctly from a AMS, the ABS extracts the 4-bit information accordingly.

BR Content (Non-aGPS)

• BR content is a requesting index of a given QoS ID and can be assigned differently by different QoS IDs.

• The 2-bit BR content indicates the size of requested BW– The mapping between the index and associated requested BW is

negotiated during flow establishment or flow modification

BR Content (aGPS)

• One QoS ID is reserved for aGPS service profile switching.

• If the quick access message is for aGPS service switch request, the 2-bit BR content is the index of aGPS service flow of the AMS.

Proposed text[insert the following text into 15.2.y.1.5.1]

15.2.y.1.5.1 quick access message formatBoth the 12-bit quick access message and the BW REQ preamble index out of total 24 sequences carry the QoS ID and 1-bit MSB of BR content. The transmitted BW REQ preamble has a mapping to the 4-bit set of [3-bit QoS ID, 1-bit MSB of BR content] based on a synchronized random number generator (RNG) maintained in the ABS and the AMS. The algorithm of RNG is FFS. The quick access message consists of 1-bit LSB BR content,10-bit request ID, and 1-bit parity. Each legitimate 10-bit request ID is mapped to one active STID, the mapping rule is FFS. The 2-bit BR content in the quick access message indicates the BW request size of the corresponding non-aGPS QoS ID. The mapping between requesting index and associated requested BW is negotiated during flow establishing or service change.

For aGPS services, one QoS ID is reserved to indicate that the quick access message is for aGPS service switching request. If the quick access message is an aGPS service switching request, the 2-bit BR content is the index of the aGPS service flow of the AMS.

Proposed quick access message  Length (bit) Description Note

Request ID

10 A request ID is mapped to an active STID. The mapping rule is FFS

Parity 1 Calculated by an AMS’s 10-bit request ID and 1-bit BW REQ info. carried in the quick access message.

BR content

2 (1-bit LSB is carried in the quick access message, 1-bit MSB is hided in the BW REQ preamble)

BW REQ size(2-bits)

Identifies the amount of bandwidth requested. The associated parameter is negotiated during service flow establishment or change

For request of non-aGPS services

Requesting aGPS flow (for aGPS service switching request)

Switches the QoS parameter sets aGPS

Only for the request of aGPS services

Appendix:A low complexity RN generation

algorithm

Slot-Machine Based Ramdon Number Generator

• Initially, AMS and ABS share a shift index• The shift index is determined randomly, and the range of the shift index is

TBD• Define the base sequence as [0,1,2,…,L-1], where L is the total number of

the BW REQ preambles• Each BW REQ preamble in the 16 BW REQ preambles is correspond to a

unique 4-bit information (3-bit QoS ID,1-bit MSB of the BR content)• Each AMS maintains an initial sequence, which is the (shift_index) cyclic

shift of the base sequence• For example, if the shift index of an AMS is 3, the initial sequence of this

AMS is [3,4,…,L-1,1,2] • When AMS transmits a BW REQ preamble, it cyclic shifts its initial

sequence by (current_state) times and choose the BW REQ preamble index according to the BR content and QoS ID. The value of the current_state may be a function of frame number, STID, and QoS ID.