doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 1 Steve Shellhammer, Nada Golmie, Robert Van Dyck, Jie Liang, Y.C. Maa, Anuj Batra, Jim Lansford, and Arun Arunachalam Tutorial on Draft

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 2 Outline of Draft Interference Modeling –Physical Layer Modeling –MAC Layer Modeling Collaborative Coexistence Mechanisms –AWMA –PTA Noncollaborative Coexistence Mechanisms –BT Packet Scheduling and Selection –BT Adaptive Frequency Hopping

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 3 System Simulation Modeling

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 4 Additive White Gaussian Noise Path loss model Received power and SIR depend on topology and device parameters: Channel Modeling

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 5 DSP based implementation of transceivers Design using typical parameters (goal is to remain non-implementation specific) Bluetooth –Non-coherent Limiter Discriminator receiver IEEE –Direct Sequence Spread Spectrum (1 & 2 Mbits/s) –Complementary Code Keying (5.5 & 11 Mbits/s) –Frequency Hopping (1 Mbits/s) Physical Layer Modeling

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 6 MAC behavioral implementation for Bluetooth and IEEE (connection mode) Frequency hopping Error detection and correction –Different error correction schemes applied to packet segments (Bluetooth) –FCS (802.11) Performance statistics collection –Access delay, packet loss, residual error, throughput MAC Layer Modeling

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 7 Bluetooth Data PacketsDM5, 2871 bits Offered Load50% SCO PacketsHV1, 366 bits Tx Power1 mW Data Rate11 Mbits/s, 1 Mbits/s ModesDirect Sequence, FH Packet Size12000 bits Offered Load50% Tx Power25 mW Bluetooth Slave Bluetooth Master AP Mobile d=1m 582.5Voice 4412Voice 9012Voice 132.3Data 1 Mbit/s FH 1 Mbit/s DS 11 Mbit/s DS 1518Data 3814Data BTBT Traffic Type Percentage of Packet Loss Typical Modeling Results

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 8 Collaborative Coexistence Mechanisms

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 9 Alternating Wireless Medium Access (AWMA) Collaborate Coexistence Mechanism for Collocated IEEE b and Bluetooth –Both in the same laptop or handheld Coordinated MAC Layer Subdivide WLAN Beacon Interval –WLAN Interval –WPAN Interval

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 10 Alternating Wireless Medium Access Synchronization of all units connected to the same WLAN Access Point Eliminates WLAN/WPAN interference due to no temporal overlap Good for high-density of WLAN/WPAN units. Does not support Bluetooth SCO link

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 11 Packet Traffic Arbitration This proposal does not address PHY or antenna issues BluetoothBaseband (up to HCI) b MAC Bluetooth Radio b PHY PTA BT Traffic traffic PTA Interface PTA- Bluetooth Interface

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 12 Packet Traffic Arbitration Collaborative techniques define rules in advance for traffic management by direct communication between systems…no learning Traffic light (TDMA) totally prevents collisions Yield, 4-way stop, etc. are also valid rules Maximizes traffic while avoiding collisions

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 13 Packet Traffic Arbitration Dynamic algorithm schedules traffic Knowledge of time-frequency collisions is key –Simultaneous transmission or reception allowed –Tx simultaneous with Rx allowed if not in-band (requires good LNA and REALLY good channel filters) –Critical for SCO operation-WLAN can work around in-band collisions This figure does not show polls/nulls, which often dominates Bluetooth traffic

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 14 Packet Traffic Arbitration Assumed MAC structure –At most one message pending for BT –At most two messages pending for WLAN PTA Engine Frequency Collision Map WLAN Stack WLAN FIFO2 WLAN FIFO1 WLAN Modem WLAN Modem Decision Logic Decision Logic Bluetooth Stack Backoff & CCA Tx Event Enable Switch Matrix Bluetooth FIFO

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 15 Adaptive Packet Selection Bluetooth provides a wide range of packet types to select from: payload length, FEC options DM1, DM3, DM5, DH1, DH3, DH5,AUX1 –Guidelines: – range limited situation: use DM packet for its FEC – interference Adaptive packet payload length selection: –Adaptive fragmentation

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 16 Adaptive Packet Scheduling Interference Estimation Maintain a Frequency Usage Table at master and slave nodes. Slave updates master’s Frequency Usage Table every update interval. Master Scheduling Policy Use “good” frequencies for master / slave transmission (upstream and downstream)

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 17 Channel Classification Draft provides an example algorithm for determining the quality of the channels. Actual implementation is left to the vendor. Metrics that could be used by the vendors include: –RSSI, PER, Carrier Sensing, and Packet ACK. Measurements can be made using: –Batch (block) techniques. –Online or offline techniques.

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 18 Adaptive Packet Scheduling Advantages: It does not require changes to the Bluetooth specifications. It conforms to FCC rules. It saves power since no transmission is wasted in bad channels It is neighbor-friendly and mitigates interference on other systems.

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 19 Adaptive Packet Scheduling

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 20 Simulation Results Bluetooth Performance BT Slave Pr [ Packet Loss] Distance between Bluetooth Slave and Mobile (meters) No Scheduling, DM1 Scheduling, DM1, DM3, DM5 No Scheduling, DM3 No Scheduling, DM Distance between Bluetooth Slave and Mobile (meters) BT Slave Mean Access Delay (seconds) Scheduling, DM1 No Scheduling, DM1 Scheduling, DM5 No Scheduling, DM5 Scheduling, DM3 No Scheduling, DM3

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 21 Simulation Results IEEE Performance Mobile Pr [ Packet Loss] Distance between Bluetooth Slave and Mobile (meters) No Scheduling, DM1 Scheduling, DM1, DM3, DM5 No Scheduling, DM3 No Scheduling, DM5

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 22 Adaptive Frequency Hopping Adaptive frequency hopping (AFH) is a non- collaborative mechanism that enables the coexistence of IEEE devices with frequency static devices in the 2.4 GHz ISM band such as IEEE b. This mechanism dynamically changes the frequency hopping sequence in order to avoid or mitigate the interference seen by both b and the device.

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 23 Adaptive Frequency Hopping There are 4 main elements of Adaptive Hopping: –AFH Capability Discovery –Channel Classification –Channel Quality Information Exchange –Adaptive Hopping Mechanism Channel classification is a mechanism for determining the quality of a channel. The channel is classified as either good or bad based on predefined metrics. –Used by both AFH and packet scheduling.

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 24 Adaptive Frequency Hopping

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 25 Adaptive Frequency Hopping The legacy hop kernel generates the hopping sequence defined in the IEEE standard. This hopping sequence is referred to as the original hopping sequence.

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 26 Adaptive Frequency Hopping Partition sequence generator imposes a structure on the original hopping sequence without changing pseudo-random properties. –For SCO+ACL, good slots are first assigned to voice slots. –For ACL only, good and bad channels are grouped together. Reduces the effects of transitions from good-to-bad channels (retransmissions) and bad-to-good channels (idle slots). Maximizes throughput.

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 27 Adaptive Frequency Hopping The frequency re-mapping function uses the partition sequence to generate the new hopping sequence. If necessary, this block uniformly re-maps the original hopping channel onto the set defined by the partition sequence. –When p(k) = 1, the re-mapping function only hops over the good channels (reduced frequency hopping).

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 28 LMP Commands The following LMP commands are needed for the AFH mechanism: Check to ensure that device is using the correct hopping sequence LMP_AFH_check_req/res Forces device back to regular hopping setLMP_regular_hopping_req Forces device to start adaptive hoppingLMP_AFH_start Request and Return of Slave’s Classification LMP_channel_metrics_req/res Identifies AFH-capable devicesLMP_features_req/res Description LMP Command

doc.: IEEE /138r0 Submission March 2002 Steve Shellhammer, Symbol TechnologiesSlide 29 Summary Draft D05 will be available on the server by Thursday AM. Motion to go to letter ballot on and on Friday AM. 40 day letter ballot to start no later than March 22, 2002.