Self-Coexistence Cycle for 802.16N Advanced Network

IEEE C802.16n-11/0182r1

Project / IEEE 802.16 Broadband Wireless Access Working Group <
Title / Self-coexistence Cycle for 802.16n Advanced Network
Date Submitted / 2011-09-12
Source(s) / Ming-Tuo Zhou1, Xin Zhang1, Liru Lu1, Hoang Vinh Dien1, Masayuki Oodo2, Hiroshi Harada1,2
National Institute of Information and Communications Technology
1: 20 Science Park Road, #01-09A/10 TeleTech Park, Singapore 117674
2: 3-4, Hikarino-oka, Yokosuka, Kanagawa, Japan, 239-0847 / Voice: +65 6771 1007
E-mail:
Re: / Call for Comments for 802.16n AWD
Abstract / 802.16n amendment draft
Purpose / To propose AWD text about self-coexistence cycle for 802.16n Advanced network
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Self-coexistence Cycle for 802.16n Advanced Network

Ming-Tuo Zhou, Xin Zhang, Liru Lu,

Hoang Vinh Dien, Masayuki Oodo, Hiroshi Harada

National Institute of Information and Communications Technology

Introduction

Self-coexistence is required in 802.16n network due to mobile HR-BS/RS/MS and relatively long interference distance at VHF frequencies. It can be achieved by sharing the same channel in time. Particularly, each cell in self-coexistence operates on one or several frames of a self-coexistence cycle exclusively.

Self-coexistence cycle is a periodical structure repeated along time for channel sharing in self-coexistence mechanism. A self-coexistence cycle may consist of a number of frames or superframes(depending on the standard that 802.16n is made amendment to). The structure of a self-coexistence needs to meet following requirements:

an HR networks in self-coexistence is able to share a minimum number of frames for data packets transmission
the HR networks in self-coexistence all have transmission opportunities for PA-/SA-preambles and superframe headers (SFHs)
the duration of self-coexistence is easy for inter-HR-BS synchronization
the self-coexistence cycle is backward compatible

Based on 802.16m frame/superframe structure and in consideration of the above requirements, a self-coexistence cycle structure for HR Advanced network is proposed in this document. It consists of twelve superframes. Structure of superframe is defined in 802.16m, i.e., each superframe consists of 4 frames and duration of each frame is 5 ms.

In normal mode of data service, an HR network transmits PA-/SA-preambles and SFH normally as that defined in 802.16m, i.e., in each of the twelve superframes of a self-coexistence cycle, it transmits an SA-preamble, an PA-preamble, and one more SA-preamble in the first symbol of the first, the second, and the third frame, respectively.

When self-coexistence mechanism is used in 802.16n network, it may lead to an HR-MS/RS loss synchronization to its serving HR-BS if no appropriate method is adopted. This is because that in the last subframe (self-coexistence zone) of the third frame of a superframe, an HR-MS/RS may receive an A-preamble from a neighbor HR network and then synchronize to the neighbor, while loss synchronization to its serving HR-BS.

In order to recover synchronization to the serving HR-BS when above case happens, it proposes that even in normal operation mode, in the first of symbol of the fourth frame of a superframe, an HR network transmits an SA-preamble.

An example is shown in Fig. 1. In this example, cell_1 operates in normal mode and it occupies all frames. It transmits an SA-preamble in the first symbol of the first frame of each superframe, a PA-preamble in the first symbol of the second frame of each superframe, an SA-preamble in the first symbol of the third frame of each superframe, an additional SA-preamble in the first symbol of the fourth frame of each superframe, and SFH in the first subframe of the first frame of each superframe of a self-coexistence cycle.

Fig. 1 Example of self-coexistence cycle structure for 802.16n cell with WirelessMAN HR-Advanced air interface operating in normal mode.

In self-coexistencemode of data service, each HR network occupies one or more frames of a superframe exclusively. However, an HR network needs to transmit PA-/SA-preamble and SFH in a superframe as that described in 802.16m, for purpose of backward compatibility. Otherwise, an AMS is unable to operate under control of an HR-BS.

To meet the requirement of backward compatibility, an HR network needs to transmit a set of A-preambles and SFH as that described in 802.16m. In another hand, each HR network occupies one or more frames of superframe exclusively. This leads to a mixed design of self-coexistence cycle in self-coexistence mode of data service, i.e., inside a superframe, each HR network occupies one or more frames exclusively except the symbols for transmission of A-preambles and SFH, while the HR networks transmit a set of A-preambles and SFH in turn in superframes of a self-coexistence cycle.

Figure 2 shows an example of structure of self-coexistence cycle where three cells (cell_1, cell_2, and cell_3) share the same frequency channel by mechanism of self-coexistence. Cell_1 occupies the first frame (F0) of all superframes of a self-coexistence cycle. Cell_2 occupies the second frame (F1) of all superframes of a self-coexistence cycle. Cell_3 occupies the third and the fourth frame (F2 and F3) of all superframes of a self-coexistence cycle. Cell_1 transmits an SA-preamble in the first symbol of the first frame (F0), a PA-preamble in the first symbol of the second frame (F1), an SA-preamble in the first symbol of the third frame (F2), and SFH in the first subframe of the first frame, of superframe SF0, SF3, SF6, and SF9. Similarly, cell_2 transmits a set of SA-preamble, PA-preamble and SFH in SF1, SF4, SF7, and SF10. Similarly, cell_3 transmits a set of SA-preamble, PA-preamble and SFH in SF2, SF5, SF8, and SF11.

Fig. 2 Example of self-coexistence cycle structure for 802.16n cells with WirelessMAN HR-Advanced air interface operating in self-coexistence mode: cell_1, cell_2, and cell_3 share the same frequency channel.

In above example, an 802.16m station in any of the three HR cells is able to receive A-preambles and SFH.

In above mixed design of self-coexistence cycle in self-coexistence mode, an HR network still needs to transmit addition preambles for synchronization among its HR stations. This is because that in a frame that an HR network does not occupy, the subordinate HR stations may loss synchronization to the serving HR-BS since in the first symbol of that frame, another HR network may transmit A-preambles normally. A solution to this issue is that the HR network transmits additional A-preamble in the first symbol of this frame. If this frame is the first, third or the fourth frame of a superframe, then the HR network transmits additional SA-preamble. If the frame is the second frame of a superframe, then the HR network transmits additional PA-preamble.

In above, if two HR networks in self-coexistence are from the same cell ID segment, then it may introduce interference each other when one of them transmits additional SA-preamble in a symbol that another transmits SA-preamble normally. To solve this issue, the HR network transmitting additional SA-preamble transmits additional substitute SA-preamble, instead of transmitting its SA-preamble. A substitute SA-preamble is a SA-preamble corresponds to a substitute cell ID, which is an cell ID in a segment different from the one of the HR network. The method to choose a substitute cell ID is as following:

If the original segment is n, then the cell chooses segment of the substitute cell ID segment as j=MOD((n+1), 3). MOD represents operation of modulo. And it chooses the substitute cell ID as cell_ID_sub = j*256 + MOD(cell_ID_org, 256), cell_ID_org is the original cell ID.

The subordinate HR stations will be informed the selected substitute cell ID.

Proposed Text for the 802.16n Amendment Working Document (AWD)

Note:

The text in BLACK color: the existing text in the 802.16nAmendment Draft Standard

The text in RED color: the removal of existing 802.16nAmendment Draft Standard Text

The text in BLUE color: the new text added to the 802.16nAmendment Draft Standard Text

[------Start of Text Proposal------]

17.3.11.1 Self-coexistence cycle

TBD

A self-coexistence cycle of consists of twelve superframes. Structure of superframe is described in WirelessMAN Advanced, i.e., each superframe consists of 4 frames and duration of each frame is 5 ms.

17.3.11.1.1 Self-coexistence cycle structure in normal mode

When an HR cell operates in normal mode, it occupies all frames of a superframe, and transmits SA-preamble, PA-preamble, and SFH (superframe header) in every superframe of a self-coexistence cycle as that described in WirelessMAN Advanced.

In addition to transmitting SA-preambles and PA-preamble as described inWirelessMAN Advanced, an HR cell transmits an SA-preamble in the first symbol of the fourth frame of each superframe.

An example is shown in Fig. xx01. Cell_1 operates in normal mode and it occupies all frames. It transmits an SA-preamble in the first symbol of the first frame of each superframe, a PA-preamble in the first symbol of the second frame of each superframe, an SA-preamble in the first symbol of the third frame of each superframe, an additional SA-preamble in the first symbol of the fourth frame of each superframe, and SFH in the first subframe of the first frame of each superframe of a self-coexistence cycle.

Figure xx01 Example of self-coexistence cycle structure for HR cell operating in normal mode.

17.3.11.1.2 Self-coexistence structure in self-coexistence mode

In self-coexistence mode, each HR cell occupies one or several frames of a superframe exclusively and the cells transmit SA-preambles, PA-preamble, and SFH normally as described in WirelessMAN Advanced in turn. In the first symbol of a frame that an HR cell occupies, it transmits an additional A-preamble if it does not normally transit an A-preamble in that symbol. If in that symbol, a neighbor HR cell transmits an SA-preamble normally, in order to avoid interference, the HR cell transmits a substitute SA-preamble if the two HR cells are in the same cell ID segment.

17.3.11.1.2.1 Transmitting A-preambles and SFH normally

To normally transmit a set of SA-preamble, PA-preamble and SFH means that an HR cell transmits an SA-preamble in the first symbol of the first frame of a superframe, a PA-preamble in the first symbol of the second frame of a superframe, an SA-preamble in the first symbol of the third frame of a superframe, and SFH in the first subframe of the first frame of a superframe, as that described in WirelessMAN Advanced.

HR cells in self-coexistencetransmit normally a set of SA-preamble, PA-preamble and SFH in the twelve superframes of a self-coexistence cycle in turn. In case that there are two HR cells in self-coexistence, one HR cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF0, SF2, SF4, SF6, SF8 and SF10, respectively, and the other HR cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF1, SF3, SF5, SF7, SF9 and SF11, respectively. In case that there are three HR cells in self-coexistence, the first cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF0, SF3, SF6 and SF9, respectively, the second HR cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF1, SF4, SF7, and SF10, respectively, and the third cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF2, SF5, SF8 and SF11, respectively. In case that there are four HR cells in self-coexistence, the first HR cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF0, SF4 and SF8, respectively, the second HR cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF1, SF5 and SF9, respectively, the third HR cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF2, SF6 and SF10, respectively, and the fourth HR cell transmits normally a set of SA-preamble, PA-preamble and SFH in SF3, SF7 and SF11, respectively.

Figure xx02 shows an example of structure of self-coexistence cycle where three HR cells (cell_1, cell_2, and cell_3) share the same frequency channel by mechanism of self-coexistence. Cell_1 occupies the first frame (F0) of all superframes of a self-coexistence cycle. Cell_2 occupies the second frame (F1) of all superframes of a self-coexistence cycle. Cell_3 occupies the third and the fourth frame (F2 and F3) of all superframes of a self-coexistence cycle. Cell_1 transmits an SA-preamble in the first symbol of the first frame (F0), a PA-preamble in the first symbol of the second frame (F1), an SA-preamble in the first symbol of the third frame (F2), and SFH in the first subframe of the first frame, of superframe SF0, SF3, SF6, and SF9. Similarly, cell_2 transmits normally a set of SA-preamble, PA-preamble and SFH in SF1, SF4, SF7, and SF10. Similarly, cell_3 transmits normally a set of SA-preamble, PA-preamble and SFH in SF2, SF5, SF8, and SF11.

Figure xx02 Example of self-coexistence cycle structure for HR cells operating in self-coexistence mode: cell_1, cell_2, and cell_3 share the same frequency channel.

Figure xx03 shows one more example of structure of self-coexistence cycle where cell_1 and cell_4 share the same frequency channel. Cell_1 occupies the first, the second, and the third frame of all superframes of a self-coexistence cycle. Cell_2 occupies the fourth frame of all superframes of a self-coexistence cycle. Similar to previous example, cell_1 normally transmits a set of SA-preamble, PA-preamble, and SFH in SF0, SF2, SF4, SF6, SF8 and SF10, of a self-coexistence cycle. Cell_4 normally transmits a set of SA-preamble, PA-preamble, and SFH in SF1, SF3, SF5, SF7, SF9, and SF11 of a self-coexistence cycle.

Figure xx03 Example of self-coexistence cycle structure for HR cells operating in self-coexistence mode: cell_1 and cell_4 share the same frequency channel.

17.3.11.1.2.2 Transmitting additional A-preambles

If an HR cell occupies a frame and it does not transmit an A-preamble normally as that described in 17.3.11.1.2.1, it transmits an additional A-preamble in the first symbol of the frame.

In above, if the frame is the second frame (F1) of a superframe, then the cell transmits additional PA-preamble in the first symbol of this frame.

In above, if the frame is the fourth frame (F3), then the cell transmits an additional SA-preamble in the first symbol of the frame.

In above, if the frame is the first (F0) or the third frame (F2) of a superframe, and the cell ID of this HR cell is in different cell ID segment as the HR cell that transmits A-preambles normally in this superframe as that described in 17.3.11.1.2.1, then this HR cell transmits an additional SA-preamble in the first symbol of the frame.

In above, if the frame is the first (F0) or the third frame (F2), and the cell ID of this HR cell is in the same cell ID segment of the HR cell that normally transmits A-preamble in this superframe as described in 17.3.11.1.2.1, then this HR cell transmits an additional substitute SA-preamble in the first symbol of the frame. An additional substitute SA-preamble carries a substitute cell ID that is in different cell ID segment of the HR cell that normally transmits A-preambles in this superframe. The method that a cell chooses a substitute cell ID and determines substitute SA-preamble is described in 17.3.11.1.2.3.

In example shown in Fig. xx02, cell_1 transmits additional (substitute) SA-preamble in the first symbol of the first frame of superframe SF1, SF2, SF4, SF5, SF7, SF8, SF10, and SF11, cell_2 transmits additional PA-preamble in the first symbol of the second frame of superframe SF0, SF2, SF3, SF5, SF6, SF8, SF9, and SF11, cell_3 transmits additional (substitute) SA-preamble in the first symbol of the third frame and additional SA-preamble in the first symbol of the fourth frame, of superframe SF0, SF1, SF3, SF4, SF6, SF7, SF9, and SF10.

In example shown in Fig. xx03, cell_1 transmits additional (substitute) SA-preamble in the first symbol of the first and the third frame of superframe SF1, SF3, SF5, SF7, SF9, and SF11, and it transmits additional PA-preamble in the first symbol of the second frame of the same superframe, cell_4 transmits additional SA-preamble in the first symbol of the fourth frame of superframe SF0, SF2, SF4, SF6, SF8, and SF10.

17.3.11.1.2.3 Choosing substitute cell ID and determining substitute SA-preamble

The method to choose a substitute cell ID is as following:

The substitute SA-preamble is corresponding to the substitute cell ID: the carrier set of the SA-preamble is the segment ID j. When the cell transmits a substitute SA-preamble, it uses the carrier set j.

The selected substitute cell ID cell_ID_sub and its segment ID j are distributed to all of its subordinate stations.