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Requirements for MAC / PHY Simulation Interface

Requirements for MAC / PHY Simulation Interface. Masahiro TAKAGI takagi@csl.rdc.toshiba.co.jp TOSHIBA Darren McNamara Darren.McNamara@toshiba-trel.com TREL. Overview. The PHY services provided to the 802.11 MAC are specified in Clause 12 of the 802.11 specification [1].

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Requirements for MAC / PHY Simulation Interface

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  1. Requirements for MAC / PHY Simulation Interface Masahiro TAKAGI takagi@csl.rdc.toshiba.co.jp TOSHIBA Darren McNamara Darren.McNamara@toshiba-trel.com TREL Masahiro TAKAGI, Toshiba

  2. Overview • The PHY services provided to the 802.11 MAC are specified in Clause 12 of the 802.11 specification [1]. • Inappropriate modeling of the PHY services would affect the results of system simulations. PHY services should be properly modeled in the simulators. • This presentation reviews the current PHY service specification and proposes the requirements for MAC / PHY interface of the simulators. • This proposal is independent of whichever PHY abstraction method is chosen. Masahiro TAKAGI, Toshiba

  3. 802.11 Protocol Reference Model • The PLCP (Physical Layer Convergence Protocol) sublayer hides the PMD (Physical Medium Dependent) sublayer from the MAC, and provides PHY-independent services to the MAC through the PHY-SAP. Masahiro TAKAGI, Toshiba

  4. List of PHY service primitives Masahiro TAKAGI, Toshiba

  5. PHY-DATA • PHY-DATA is used when the MAC transmits or receives an octet of data to or from the PHY. • Simulators may use a frame level data transfer model between the MAC and PHY, so this octet level data transfer behavior can be safely ignored. Masahiro TAKAGI, Toshiba

  6. PHY-TXSTART • PHY-TXSTART is used when the MAC requests the PHY to transmit a frame. TXVECTOR specifies the parameters (Rate, Length, etc.) to be used in the transmission. • TXVECTOR parameter may contain any PHY dependent information which is defined in the relevant specifications (proposal or existing standard). • The simulator may use PHY dependent parameters in addition to Rate and Length when the MAC requests the PHY to transmit a frame. Masahiro TAKAGI, Toshiba

  7. PHY-TXEND • PHY-TXEND terminates transmission prematurely. • Simulations may safely ignore this service. Masahiro TAKAGI, Toshiba

  8. PHY-RXSTART • PHY-RXSTART is used when the PHY notifies the MAC of the start of a frame reception. RXVECTOR specifies the parameters (Rate, Length, etc.) for the frame reception. • RXVECTOR parameter may contain any PHY dependent information which is defined in the relevant specifications (proposal or existing standard). • The simulator may use PHY dependent parameters in addition to Rate and Length when the PHY notifies the MAC of frame reception. Masahiro TAKAGI, Toshiba

  9. PHY-RXEND • Normal frame reception (PHY-RXEND.indication (NoError) with correct FCS) triggers several events at the MAC. • A frame reception with errors triggers an EIFS at the MAC in the following cases: • PHY-RXEND.indication (NoError) and FCS check fail at the MAC. • PHY-RXEND.indication (FormatViolation, CarrierLost or UnsupportedRate) • This service is covered by the existing discussions on PHY abstraction by the SMSC, as only a ‘Reception successful or unsuccessful’ notification is required by simulation. Masahiro TAKAGI, Toshiba

  10. PHY-CCA • The MAC uses PHY-CCA to determine if the PHY carrier sense state is idle or busy. • A simulator should consider all the PHY carrier sense methods (energy, preamble etc.) when determining the setting of PHY-CCA. • The carrier sense sensitivity level should be appropriately adjusted according to the conditions specified in the relevant proposal or standard. • PHY-CCA shall stay in the busy state for the frame duration once this value is determined from the information contained in the PLCP header. Masahiro TAKAGI, Toshiba

  11. PHY-CCARESET • PHY-CCARESET is used when the NAV is reset. • A simulator should set the PHY carrier sense state to idle if the NAV is reset. Masahiro TAKAGI, Toshiba

  12. PHY-CCA for Coexistence • Usage models [2] include scenarios for legacy coexistence evaluation • Scenario 9 (Mixed-Mode BSS) (Mandatory) • Scenario 11 (Co-channel legacy BSS) (Mandatory) • Scenario 19 (Point-to-Point Legacy Sharing Throughput Test for CC 15 (Mandatory) • CCA is the primary MAC deferral mechanism • If proposals include a non backwards compatible PLCP preamble and header for HT operation, this should affect the CCA sensitivity threshold used during reception by legacy STAs [1]. • Calculation of RX power and knowledge of PLCP compatibility is part of the PHY abstraction, and therefore the state of PHY-CCA should be reported by the PHY abstraction. Masahiro TAKAGI, Toshiba

  13. Conclusion • Most of the PHY services which would affect simulation results have already been considered in the SMSC. • CCA at legacy STA should not be overlooked, since it would affect the results of mixed-mode and legacy coexistence scenarios. • PHY-CCA needs to be determined and reported by the PHY abstraction. Masahiro TAKAGI, Toshiba

  14. References • [1] IEEE Wireless LAN Edition -A compilation based on IEEE Std 802.11TM-1999 (R2003) and its amendments- • [2] Usage Models (11-03/802r12 ) Masahiro TAKAGI, Toshiba

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