IPv6 over Bluetooth AdvertisementsAn alternative approach to IP over BLE

2025-04-27 0 0 4.43MB 10 页 10玖币

侵权投诉

IPv6 over Bluetooth Advertisements:

An alternative approach to IP over BLE

Hauke Petersen

hauke.petersen@fu-berlin.de

Freie Universität Berlin

Germany

János Brodbeck

brodbeck@zedat.fu-berlin.de

Freie Universität Berlin

Germany

Thomas C. Schmidt

t.schmidt@haw-hamburg.de

HAW Hamburg

Germany

Matthias Wählisch

m.waehlisch@fu-berlin.de

Freie Universität Berlin

Germany

ABSTRACT

The IPv6 over Bluetooth Low Energy (BLE) standard denes the

transfer of IP data via BLE connections. This connection-oriented

approach provides high reliability but increases packet delays and

requires substantial overhead to manage BLE connections. To over-

come these drawbacks we present the design and implementation

of IPv6 over BLE advertisements, a standard-compliant connection-

less approach. We deploy our proposal on low-power IoT hardware

and comparatively measure key network performance metrics in a

public testbed. Our results show that IP over BLE advertisements of-

fers network performance characteristics complementary to IP over

connection-based BLE, trading lower reliability for shorter latency.

1 INTRODUCTION

The Internet of Things (IoT) is highly fragmented [

]. In the low-

power wireless IoT, heterogeneous link layer technologies compete,

each requiring dedicated (smart) gateways to connect to the Internet.

Bluetooth Low Energy (BLE) is the most deployed low-power radio

technology today [

] and the IP over BLE standard [

]

allows to seamlessly connect BLE devices to the Internet. Further-

more, BLE oers best in class low-power characteristics [

]

as well as reliable network performance [

], making it a promising

default link layer in the low-power IoT.

IP over BLE, however, works on top of BLE connections, which

leads to some disadvantages. First, before exchanging IP data, any

node must open BLE connections to one or more adjacent peers.

Managing these connections automatically poses overhead on BLE

nodes. Second, the number of concurrent BLE connections is typ-

ically limited to

≈

15 peers due to restrictions in memory and ra-

dio scheduling. Third, the current IP over BLE standard increases

packet delays as BLE connections are time-slotted. Typical laten-

cies of IP over BLE networks are, in some scenarios, substantially

larger compared to networks based on carrier-sense multiple access

(e.g., IEEE802.15.4) [32].

In order to mitigate the disadvantages of the current IP over

BLE standard, we propose to explore the transfer of IP data using

the connection-less mode of BLE. We do not aim for replacing the

existing connection-oriented IP over BLE design but to oer an

alternative based on the same technology, to allow IoT developers to

optimize deployments depending on requirements. As both designs

are based on the same software (BLE and IP stacks) and hardware

(radios) they can be deployed and run simultaneously, which nally

will increase IoT use cases for BLE networks.

In this work, we present the protocol design and prototype im-

plementation of IPv6 data over connection-less BLE. We utilize

the extended advertisements, which were introduced in Bluetooth

version 5.0 [

]. Extended advertisements have the advantage of

oering a MTU of up to 65 Kbytes through packet fragmentation

capabilities provided by BLE controller. They are, thus, able to carry

full IPv6 packets with a minimum MTU of 1280 bytes on top of

a lean software system. In contrast to this, legacy BLE advertise-

ments would allow only for a maximum payload of 31 bytes per

packet, which would require complex fragmentation schemes im-

plemented on an intermediate layer between IP and BLE in addition

to 6LoWPAN-based header compression [7, 27].

We systematically measure key performance metrics in practice

based on 15 low-power BLE nodes in the FIT IoTlab testbed [

]. We

analyze reliability, latency, and energy consumption in dierent

single- and multi-hop network topologies and compare them to

the performance of connection-based IP over BLE networks. Our

results show that using advertisements oers lower latency (on

average 1.5

to 5

lower for comparable congurations) but less

reliability (1% to 80% packet loss vs

0.01%) and increased power

consumption (radio always on).

Currently, Bluetooth Mesh [

] is the only standard to transfer

(proprietary) data over connection-less BLE. In contrast to our pro-

posal, however, Bluetooth Mesh does not support arbitrary IP pack-

ets but is limited to the ooding of specic, small data frames

(<20 bytes), and does not support fragmentation. Bluetooth Mesh

aims for vendor-specic simplied scenarios, whereas our proposal

targets exible Internet-like deployments.

In summary, we make the following contributions:

(1)

The rst, standard-compliant design to transfer IPv6 data

over BLE extended advertisements. (§ 3.1)

(2)

A publicly available, open source implementation based on

the operating system RIOT and the BLE stack NimBLE. (§ 3.2)

(3)

Reproducible experiments conducted on real-world hard-

ware, and all artifacts. (§ 4)

(4)

A comparative performance evaluation including network

and system measures to show protocol mechanics in contrast

to connection-based IP over BLE networks. (§ 5–§ 6)

arXiv:2210.06236v1 [cs.NI] 12 Oct 2022

2 BACKGROUND

BLE supports three modes to transfer data: the connection-less

legacy advertising mode, the connection-less extended advertising

mode, and the connection-based mode. Connection-less communica-

tion is usually used to enable the discovery of services and to broad-

cast data for further processing to unknown peers. Connection-

based communication aims for communication between direct

peers, e.g., in the IP over BLE standard [

]. This section briey

presents core background on all three modes with a focus on em-

bedding data.

2.1 Connection-less BLE Communication

Legacy advertising is used in Bluetooth Mesh [

] and the extended

advertising mode was introduced in Bluetooth 5.0 [16].

Legacy Advertising.

Legacy advertising supports a maximum pay-

load of 31 bytes. The advertisement packets are sent periodically in

so-called advertising events during an advertising interval, depend-

ing on the conguration between 20ms and 10.48s, see Figure 1.

Each advertisement packet is sent via the primary advertisement

channels, three predened channels that are exclusively reserved

for advertisements to achieve some level of robustness. This mode

is unidirectional (no link layer acknowledgements) and unmanaged

(no CSMA scheme).

To receive advertisements, nodes listen periodically on one of

the primary advertising channels (scan event) based on the scan

interval. An active radio in RX mode is expensive in terms of energy.

The Bluetooth standard, thus, allows the receiver during each scan

event to only activate the radio during the scan window. If the scan

window is shorter than the advertising interval, advertising packets

might get lost. There exist a number of approaches on how these

parameters can be optimized to balance energy usage and delivery

probability [24, 34, 35].

In common advertising use-cases (e.g., beaconing), devices use

a xed payload. When considering less predictable application

data such as carried in IP packets, this data should preferably be

sent within a single advertising event. Since there is no guarantee

that an advertising event is received, a single payload is typically

transmitted in multiple advertising events, hence implementing

a xed number of link layer packet retransmissions. This is, for

example, applied in Bluetooth Mesh, which defaults to carry the

same payload in 5 connection events [17].

When transmitting IP data using legacy advertisements, the

limited payload becomes a major bottleneck. To encapsulate IP data

into the payload of advertising packets, an additional advertising

data header of at least 6 bytes is required, leaving only 25 bytes for IP

data. Even when using header compression techniques (e.g., dened

in 6LoWPAN [

]), packet fragmentation would then be needed.

Extended Advertising.

Extended advertising allows for larger

payloads and is based on legacy advertising. Instead of carrying

data in (very limited) packets via the primary channels, extended

advertising uses these packets to refer to one of 37 data channels

and a start time. The actual payload is then sent at the specied

start time on the given data channel in one or more chained data

packets (see Figure 1).

A A

time

Legacy advertising

A B B B

Extended advertising

Connection-based

PPP

A A

Ack A Ack B Ack B Ack

P P P B B

C37 C38 C39 Cn [0:36] Cn+1 [0:36]

C37 C38 C39

Cn [0:36] Cn+1 [0:36]

TX RX

C37 C38 C39

Advertising event N Advertising event N+1

Connection Event N

Advertising event N+1

Connection Event N+1

Advertising event N

time

150µs

[0:10ms]

[0:10ms][300µs:2.45s]

[20ms:10.48s]

[7.5ms:4s]

Figure 1: BLE packet ow when transferring payloads A

and B using legacy and extended advertisements as well as

connection-based communication.

By containing only a short pointer, the packets sent on the 3

advertising channels need less air time for transmission. This re-

duces collision probability on those potentially crowded channels.

The collision probability for data packets is reduced by utilizing all

37 data channels for their transmission.

By splitting the payload over multiple chained packets, extended

advertising allows to transfer up to 65 Kbytes in a single advertising

event. Fragmentation and reassembly into link layer data packets is

done by the Bluetooth controller, which relieves higher layers from

implementing fragmentation schemes to transfer full IPv6 MTUs.

2.2 Connection-based BLE Communication

In contrast to advertisements, which are transmitted in the broad-

cast domain, BLE connections are always point-to-point. In a con-

nection between two nodes, one node acts as connection coordinator

while the peer node is the connection subordinate.

Similar to adver-

tising events, the communication in the connection-based mode is

structured into connection events. Each connection event consists of

at least a single data packet exchange between the coordinator and

subordinate. This can be repeated multiple times in the same event

until no payload is left to send or the next connection event starts.

If one of the peers has no data to send, it will send empty packets.

Each connection event takes place on one of the 37 available data

channels.

BLE connections provide a point-to-point service guaranteeing

rst-in-rst-out, in-order, and complete data delivery. To achieve

this, data packets are retransmitted on the link layer until they

are acknowledged. If by either side no valid packet is received

during a specic amount of time, the connection is considered

lost and is closed. Consequently, as long as connections are active,

there is no packet loss on the link layer [

]. The IP over BLE

standard [13, 15, 28] is using this connection-based mode.

The terms “coordinator” and “subordinate” used in this paper diverge from Bluetooth

specications, to support non-discriminatory language.

文档加载中……请稍候！
如果长时间未打开，您也可以点击刷新试试。

下载文档到电脑，查找使用更方便

10 玖币 0人已下载

立即下载

摘要：

IPv6overBluetoothAdvertisements:AnalternativeapproachtoIPoverBLEHaukePetersenhauke.petersen@fu-berlin.deFreieUniversitätBerlinGermanyJánosBrodbeckbrodbeck@zedat.fu-berlin.deFreieUniversitätBerlinGermanyThomasC.Schmidtt.schmidt@haw-hamburg.deHAWHamburgGermanyMatthiasWählischm.waehlisch@fu-berlin.deFr...

展开>> 收起<<

IPv6 over Bluetooth AdvertisementsAn alternative approach to IP over BLE.pdf

共10页,预览2页

还剩页未读，继续阅读

声明：本站为文档C2C交易模式，即用户上传的文档直接被用户下载，本站只是中间服务平台，本站所有文档下载所得的收益归上传人(含作者)所有。玖贝云文库仅提供信息存储空间，仅对用户上传内容的表现方式做保护处理，对上载内容本身不做任何修改或编辑。若文档所含内容侵犯了您的版权或隐私，请立即通知玖贝云文库，我们立即给予删除！

IPv6 over Bluetooth AdvertisementsAn alternative approach to IP over BLE

相关推荐

开通VIP享超值会员特权

作者详情

相关内容

热门标签

举报选择: