quick access message for ieee 802.16m document number: ieee c802.16m-09_905 date submitted:...

Quick Access Message for IEEE 802.16m

Document Number:IEEE C802.16m-09_905Date Submitted:2009-04-27

Source: Tsung-Yu Tsai, Yi-Ting Lin, Kanchei(Ken) Loa,Jiun-Je Jian, Youn-Tai Lee, Chun-Yen Hsu, Chiu-Wen Chen E-mail: tyt@nmi.iii.org.tw Institute for Information Industry(III) Shiann-Tsong Sheu, Chih-Cheng Yang National Central University

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 AWD

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Introduction• Considerations for the quick access message

– These information should be carried in the quick access message• STID: Indentify the requesting station• FID: Extract QoS info. associated with each flow to facilitate ABS

for performing call admission control, scheduling, QoS policing• BW Request info.: The content of requesting BW

– Error detection design• Without error detection design, the integrity of the information can

not be guaranteed– The selection of transmitted sequence

• The selection of sequence shall be “random” enough and independent of user’s information (STID, FID etc.)

– Minimize the sequence collision probability

Design Principles• The quick access message and the selected BW REQ preamble

carry the FID information– The STID is extracted from the quick access message– The BW REQ preamble could map to a FID given that STID is known.

• The quick access message includes BW REQ information(3-bit) and 10-bit temporary ID, and 1-bit parity– The 10-bit temporary ID is generated by performing a hash function over

10-bit reduced STID (e.g. LSB of STID)• “Randomizing” or “Reordering” the reduced STID to increase the error detection ability

– 1-bit parity can guarantee to detect odd number errors • The 3-bit BW-REQ information in quick access message is

requesting index for a given flow and can be assigned differently for different flows– The mapping between requesting index and associated requested BW is

negotiated during flow establishing or service change

STID search procedure and error detection

• When the ABS received the quick access message, it first checks the parity bit, if pass, it finds the corresponding active STID associated to the temporary ID– To facilitate the searching procedure, a lookup table can be maintained

• If no such active STID is found or parity check does not pass, the ABS regards the quick access message as corrupted or collided(error detection)

• Otherwise, if the ABS finds one legitimate STID, then it further verifies the legitimacy of the requesting FID from this station (the method of verifying FID is described in the next page)

• This scheme requires 14-bit message size and provide additional benefit of error detection for the quick access message.

Flow ID search procedure• For different flows, a random number generator is maintained in

the ABS and the AMS in a synchronized manner– When an AMS sends a BW REQ for a given FID. The BW REQ

preamble is selected by the random number (RN) generator– The algorithm to generate the random number is TBD

• For example, RN=(a*current_state + p) mod m– a : pre-defined muliplier– current_state : f(frame #, seed), where seed may be f(STID, FID)– p : per-defined increment number– m : modulo, may be sequence length or a mapping to the index of

sequence• Another low complexity RN generator is illustrated in the

appendix

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

15.2.y.1.5.1 quick access message formatBoth the 14-bit quick access message and the BW REQ preambleindex out of total 22 (FFS) sequences carry the FID information. The transmitted BW REQ preamble has a mapping to the requesting FID based on a synchronized random number generator(RNG) maintained in the ABS and the AMS. The algorithm of RNG is FFS. In the quick access message, the 3-bit BW REQ info.,10-bit temporary ID, and 1-bit parity are included. The 10-bit temporary ID which is generated by performing hash function over reduced STID(e.g. 10 –bit LSB of STID) to reorder the reduced STID. After reordering by the hash function, the temporary ID could improve the ability of error detection. The 3-bits BW REQ information in the quick access message is the requesting index of a given flow and can be assigned differently by different flows. The mapping between requesting index and associated requested BW is negotiated during flow establishing or service change. If the FID is associated with adaptive grant and polling service (aGPS) scheduling class, the requesting index is used for QoS parameter adaptation. If the FID is associated with non-aGPS scheduling class, the requesting index is used for indicating the BW REQ size.

Proposed quick access message  Length

(bit)Description Note

BW REQ Info. 3 BW REQ size(3-bits)

Identifies the number of requested by a flow. The associated parameter is negotiated during flow establishing or service change

For the common transport connections

SF QoS Parameter Set Flag (for aGPS)(1-bit, 1-bits reserved)

Switches the QoS parameter sets of aGPS:0: Primary SF QoS parameter set1: Secondary SF QoS parameter set

Only for the aGPS connections

Temporary ID 10 Temporary ID is generated by performing hash function (FFS) over reduced STID(e.g. 10-bit LSB STID)

Parity 1 Calculated by an AMS’s 10-bit temporary ID and Info.

Appendix:A low complexity RN generation

algorithm

Slot-Machine Based RNG• Initially, AMS and ABS share an initial value

– The initial value is determined randomly, and the range of the initial value is TBD

• Define the base sequence as [0,1,2,…,L-1], where L is the total number of the BW REQ sequences– 16 positions in the sequence are selected to correspond to a flow ID

• An initial sequence is associated to an AMS, which is defined as the (initial_value) cyclic shift of the base sequence– For example, if the of an AMS initial value = 3, the initial sequence of

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

sequence by (current_state) times and choose the sequence index according to the position the flow ID corresponding to. The definition of current_state is described in page 5

Procedure for an AMS to