线性调频扩频-异步脉冲码多址
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9
Experiment: in congested environments
6 transmitters APCMA占空比: 2%~10%, LoRa占空比: 0.078%~0.39%
transmitters number from 1 to 6 APCMA duty cycle: 10% LoRa duty cycle 0.39%
(a) PER with various signal powers. The noise power is fixed
(b) PER of CSS-APCMA with various SFs.
Fig.3 PER of CSS-APCMA and LoRa with various SNRs and SFs
C− 2x, and x
4
APCMA: Decoding scheme
5
APCMA: Decoding scheme
Same codewords table at Tx and Rx
Shift register at the receiver
Each cell in this shift register represents one time slot,
11
Conclusion
评估了CSSபைடு நூலகம்APCMA的有效性 根据第一个实验，CSS-APCMA在拥挤环境下的PER比LoRA低 第二个实验表明，在低噪声条件下，CSS-APCMA比OOK-APCMA具有更低的PER 在[3]中，实现了在920MHz频段使用500个CSS-APCMA发射机器件的大规模实验 我们目前正在致力于1500个发射机的实现，以便进一步进行大规模实验。
8
Experiment: in congested environments
CSS-APCMA 与 LoRa对比，
用每秒总包数(TNPS)来度量不同流量需求下的包错误率(PER)。 spreading factor (SF) ：7。 bandwidth ：250kHz。 payload size：1Byte。
7
Implementation
implementations of CSS-APCMA, OOK-APCMA, and LoRa on software-defined radios all use the 920 MHz band LoRa based on [7]
每个发射机根据编码表将其数据转换成基于脉冲的码字，然后对其进行调制 并通过其USRP发送。
Performance evaluation of CSS-APCMA for massive IoT using GNU Radio/USRP
线性调频扩频 异步脉冲码多址
Abstract
Asynchronous Pulse Code Multiple Access (APCMA) : Massive IoT, high density,
• [2] APCMA每台设备吞吐量大于LoRaWAN • [3] CSS(Chirp Spread Spectrum)-APCMA，在低接收信号功率下提高接收灵敏
500个APCMA发射机的高密度通信，
3
APCMA: Encoding scheme
Pulse-based, Communication through Silence (CtS), encodes data as an interval between two pulses
Pulse trains small and sparse low power consumption Codewords
contain four or more pulses, Correlations between codewords are minimized This Paper: Pulse codes: four pulses per codeword, delimit intervals of lengths x,
2
Introduction
Low Power Wide Area (LPWA): LoRa, Sigfox, and ELTRES • packet losses or collisions in high-density and congested environments.
Asynchronous pulse code multiple access (APCMA) • high-density environment, senders collide • encodes data as pulse-based codewords • 允许不同发送方的码字冲突时高概率解码
decoding algorithm works even when multiple pulse codewords are received
simultaneously
6
Chirp Spread Spectrum (CSS)
基于OOK-APCMA在FPGA上的实现，文[6]进行了100个器件的实验。 LPWA systems: i.e. LoRa and ELTRES:
a pulse is encoded as a 1 if its power exceeds a threshold, otherwise encoded as 0
contents of the register shift to the right each clock cycle, whereby each new incoming pulse enters the register from the left。
At each clock cycle, the contents of the shift register are compared with the code table
and if a match is found, the corresponding codeword is detected and decoded. This
使用CSS来提高检测性能，并支持距离达数十公里的广域通信
CSS: chirp signals: frequencies increase or decrease with time broad spectrum resistance to noise
CSS-APCMA achieved in [3,4], not compared with other schemes
Benchmark: On-Off Keying APCMA (OOK-APCMA), LoRa Experiments:
Lower packet error rate (PER) than LoRa in congested environment Lower PER than OOK-APCMA in noisy environment 实际上板验证 CSS-APCMA Suitable for massive IoT
接收机的USRP通过在PC上运行的GNU无线电程序,通过解调IQ分量来检测脉冲。 为了检测chirp signal, ，将接收的脉冲信号乘以down-chirp ，然后应用FFT来检 测received chirp signal的峰值功率。 在每个时钟周期将检测结果输入移位寄存器，用于解码APCMA脉冲码。
12
感谢各位老师 请您批评指正
Fig.2(a) Packet error rates at various
Fig.2(b) Packet error rates at various TNPSs,
TNPSs, which depend on the duty cycle.
which depend on the number of transmitters.
Fig. 2: PER of CSS-APCMA and LoRa at various TNPSs in a congested environment.
10
Experiment: under low SNR condition
SF: 7~10 Bandwidth: 250kHz Payload size: 1Byte Number of transmitters: 6 Message duty cycle: 10%
Experiment: in congested environments
6 transmitters APCMA占空比: 2%~10%, LoRa占空比: 0.078%~0.39%
transmitters number from 1 to 6 APCMA duty cycle: 10% LoRa duty cycle 0.39%
(a) PER with various signal powers. The noise power is fixed
(b) PER of CSS-APCMA with various SFs.
Fig.3 PER of CSS-APCMA and LoRa with various SNRs and SFs
C− 2x, and x
4
APCMA: Decoding scheme
5
APCMA: Decoding scheme
Same codewords table at Tx and Rx
Shift register at the receiver
Each cell in this shift register represents one time slot,
11
Conclusion
评估了CSSபைடு நூலகம்APCMA的有效性 根据第一个实验，CSS-APCMA在拥挤环境下的PER比LoRA低 第二个实验表明，在低噪声条件下，CSS-APCMA比OOK-APCMA具有更低的PER 在[3]中，实现了在920MHz频段使用500个CSS-APCMA发射机器件的大规模实验 我们目前正在致力于1500个发射机的实现，以便进一步进行大规模实验。
8
Experiment: in congested environments
CSS-APCMA 与 LoRa对比，
用每秒总包数(TNPS)来度量不同流量需求下的包错误率(PER)。 spreading factor (SF) ：7。 bandwidth ：250kHz。 payload size：1Byte。
7
Implementation
implementations of CSS-APCMA, OOK-APCMA, and LoRa on software-defined radios all use the 920 MHz band LoRa based on [7]
每个发射机根据编码表将其数据转换成基于脉冲的码字，然后对其进行调制 并通过其USRP发送。
Performance evaluation of CSS-APCMA for massive IoT using GNU Radio/USRP
线性调频扩频 异步脉冲码多址
Abstract
Asynchronous Pulse Code Multiple Access (APCMA) : Massive IoT, high density,
• [2] APCMA每台设备吞吐量大于LoRaWAN • [3] CSS(Chirp Spread Spectrum)-APCMA，在低接收信号功率下提高接收灵敏
500个APCMA发射机的高密度通信，
3
APCMA: Encoding scheme
Pulse-based, Communication through Silence (CtS), encodes data as an interval between two pulses
Pulse trains small and sparse low power consumption Codewords
contain four or more pulses, Correlations between codewords are minimized This Paper: Pulse codes: four pulses per codeword, delimit intervals of lengths x,
2
Introduction
Low Power Wide Area (LPWA): LoRa, Sigfox, and ELTRES • packet losses or collisions in high-density and congested environments.
Asynchronous pulse code multiple access (APCMA) • high-density environment, senders collide • encodes data as pulse-based codewords • 允许不同发送方的码字冲突时高概率解码
decoding algorithm works even when multiple pulse codewords are received
simultaneously
6
Chirp Spread Spectrum (CSS)
基于OOK-APCMA在FPGA上的实现，文[6]进行了100个器件的实验。 LPWA systems: i.e. LoRa and ELTRES:
a pulse is encoded as a 1 if its power exceeds a threshold, otherwise encoded as 0
contents of the register shift to the right each clock cycle, whereby each new incoming pulse enters the register from the left。
At each clock cycle, the contents of the shift register are compared with the code table
and if a match is found, the corresponding codeword is detected and decoded. This
使用CSS来提高检测性能，并支持距离达数十公里的广域通信
CSS: chirp signals: frequencies increase or decrease with time broad spectrum resistance to noise
CSS-APCMA achieved in [3,4], not compared with other schemes
Benchmark: On-Off Keying APCMA (OOK-APCMA), LoRa Experiments:
Lower packet error rate (PER) than LoRa in congested environment Lower PER than OOK-APCMA in noisy environment 实际上板验证 CSS-APCMA Suitable for massive IoT
接收机的USRP通过在PC上运行的GNU无线电程序,通过解调IQ分量来检测脉冲。 为了检测chirp signal, ，将接收的脉冲信号乘以down-chirp ，然后应用FFT来检 测received chirp signal的峰值功率。 在每个时钟周期将检测结果输入移位寄存器，用于解码APCMA脉冲码。
12
感谢各位老师 请您批评指正
Fig.2(a) Packet error rates at various
Fig.2(b) Packet error rates at various TNPSs,
TNPSs, which depend on the duty cycle.
which depend on the number of transmitters.
Fig. 2: PER of CSS-APCMA and LoRa at various TNPSs in a congested environment.
10
Experiment: under low SNR condition
SF: 7~10 Bandwidth: 250kHz Payload size: 1Byte Number of transmitters: 6 Message duty cycle: 10%