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Mobility Enhancement of Patients Body Monitoring based on WBAN with Multipath Routing

Yasna Ghanbari Birgani, Nastooh Taheri Javan, Mohsen Tourani

arXiv:2610.03042v1cs.NI

TL;DR

Low-power WBAN devices’ short range makes patient mobility a challenge in hospital monitoring, while ad hoc multihop routing can add delay and packet loss. The paper proposes RMPR, which discovers and uses multiple routes; simulations report lower delay and energy consumption and more favorable packet delivery than the compared methods, alongside higher routing overhead.

Abstract

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One of the promising applications of wireless sensor networks (WSNs) is monitoring of the human body for health concerns. For this purpose, a large number of small sensors are implanted in the human body. These sensors altogether provide a network of wireless sensors (WBANs) and monitor the vital signs and signals of the human body; these sensors will then send this information to the doctor. The most important application of the WBAN is the implementation of the monitoring network for patient safety in the hospital environment. In this case, supporting patients' mobility is one of the basic needs, which has been underestimated in recent studies. The problem that involves providing the required energy for the units used in this type of network is challenging; for this reason, sent/received units with very low power consumption and with a very small radius are used in order to save energy. The resulting small sending range leads to the lack of support for patients' mobility. In this paper, the ad hoc mode is suggested for use to establish a network and a multipath routing algorithm for the purpose of supporting patients' mobility in a hospital setting. The results of the simulation show that, in addition to supporting patients' mobility, the use of the proposed idea instead of previously presented protocols reduces delays in data transmission and energy consumption; it also increases the delivery rate depending on the destination and the lifetime of the network, while increasing routing overhead.

I. INTRODUCTION

Hospital WBANs must support patient mobility despite low-power devices’ short range. The paper motivates ad hoc multipath routing as a mobility-supporting approach, balancing transmission performance against routing overhead.

I. INTRODUCTION

  • Medical WBAN sensors measure physiological parameters and send the data to a nearby access point, which forwards it through another network to medical staff.The passage gives WLAN as an example of the intervening network.Source: §I · p. 1
  • Low-power WBAN devices have short ranges, so limited coverage can leave mobile hospital patients confined to their beds.The passage notes that this may suit patients unable to move, but not the needs of patients in other hospital sectors.Source: §I · p. 1
  • GSM-based monitoring depends on cell-phone performance; high transmission delay and network unavailability can disrupt critical medical applications.Network congestion is one stated cause of unavailability.Source: §I · p. 1
  • Covering a hospital with multiple access points can support single-hop delivery and low end-to-end delay, but may require tens or hundreds of access points.The passage identifies the number of access points as a cost of this approach.Source: §I · p. 2
  • In ad hoc mode, patient devices also route other stations’ data, enabling patients to form a mobile network.The passage describes fast, low-cost setup, but notes that multihop transmission raises delay and network breaks can increase packet loss.Source: §I · p. 2
  • The proposed multihop protocol discovers several routes and sends data through them simultaneously to reduce the impact of topology changes and link detachment on packet loss.This introduction describes the approach as increasing reliability.Source: §I · p. 2

II. RELATED WORKS

Prior work addresses WBAN routing, mobility, reliability, and energy, but the paper identifies multihop delay and link-related packet loss as challenges for hospital ad hoc networks. It proposes RMPR to discover and use multiple routes, accepting increased routing overhead.

II. RELATED WORKS

  • A prior WBAN protocol used TDMA channel access, gossip-based routing, and link-quality measurements to address topology changes and energy consumption.The passage says stations could use topology changes immediately according to their needs.Source: §II · p. 2
  • Work on multistep WBAN routing discussed channel-access-layer changes but is described as not considering station movement [9 and 10].Source: §II · p. 2
  • Prior mobility-aware routing estimated topological change from node movement history, while another approach estimated future link conditions from past link quality.The passage reports latency reductions for compared with some existing methods.Source: §II · p. 2
  • Hospital WBAN studies included an implementation of relationships between WBANs and a quality-of-service-aware routing proposal that categorized devices by energy availability.The passage says reliability and quality-of-service parameters were not considered in.Source: §II · p. 2
  • Hospital ad hoc WBANs face multihop transmission delay and packet loss associated with deteriorating or lost links; prior mobility-focused research is described as limited.These are presented as two inherent problems with ad hoc data transmission in these networks.Source: §II · p. 2
  • RMPR discovers multiple appropriate paths and sends data over up to three, using route reliability to address packet loss and multipath transmission to reduce delay.The paper states that increased routing overhead is a cost of this approach.Source: §II · pp. 2–3

A. Route Discovery

RMPR discovers multiple node-disjoint routes on demand, then uses a Strength Factor to select a route. Route requests are flooded with duplicate checks, and replies travel back along discovered paths.

A. Route Discovery

  • RMPR floods route requests and records seen requests to avoid loops, discovering only node-disjoint paths at the source.The destination sends replies back along each request's reverse path.Source: A. Route Discovery · p. 3
  • Each node multiplies the packet's Strength Factor by the received-power ratio, producing a path value such as 0.56 for S-A-D.The source initializes the field to 1; the example starts with a 0.8 ratio on S-A.Source: A. Route Discovery · p. 3
  • The destination returns replies for discovered routes, and the source selects the route with the highest Strength Factor.Figure 1 depicts the route discovery phase.Source: A. Route Discovery · p. 3, Figure 1 · p. 3

B. Route Maintenance

Patient mobility can degrade or detach routes, leaving the source to prioritize among discovered paths. RMPR sends measurement packets from destination to source to update route Strength Factors and select a stronger path.

B. Route Maintenance

  • Mobility can reduce route quality or detach routes, so the source must prioritize among routes discovered earlier.Figure 2 depicts the route maintenance phase.Source: B. Route Maintenance · p. 3, Figure 2 · p. 4
  • Strength Factor is a normalized display of signal strength, using received signal power relative to the acceptable lower threshold.The prose identifies SXY as the signal power node X receives from node Y, and Smin as the lower threshold.Source: B. Route Maintenance · p. 3
  • When the number of powerful routes falls below a threshold, the source can replace them by rerunning route discovery.Source: B. Route Maintenance · p. 4
  • Measurement packets update each route's cumulative Strength Factor, allowing the source to choose the route with the higher value; S-A-D is 0.49 in the example.The destination initializes the field to 1, and each node multiplies in its received-link Strength Factor.Source: B. Route Maintenance · pp. 3–4

C. Data Sending

The source sends data simultaneously over two routes, alternating packets between them. It seeks reliable, time-efficient routes and maintains paths.

C. Data Sending

  • The source alternates packets between two routes to send data simultaneously.It uses a retention (path maintenance) mechanism while seeking the most powerful routes in terms of time efficiency.Source: C. Data Sending · p. 4
  • The source prioritizes routes with higher reliability when sending data.Route selection also considers time efficiency and path maintenance.Source: C. Data Sending · p. 4
  • A retention mechanism is used to maintain paths as the source discovers routes.The source seeks the most powerful routes in terms of time efficiency.Source: C. Data Sending · p. 4

III. EVALUATION AND RESULTS

The evaluation uses OMNet++ with Castalia to compare three multihop, ad hoc algorithms under increasing patient mobility. The simulation uses a specified node, radio, mobility, and traffic setup.

III. EVALUATION AND RESULTS

  • The simulation compares the proposed RMPR with the referenced algorithms [14] and in multihop ad hoc mode.The authors state these methods cannot be compared with non-ad hoc methods because of inherent differences.Source: §III · p. 4
  • Algorithm [14] divides devices into three energy-based categories, including non-rechargeable body nodes, and measures route reliability.The authors note implementation limitations and complexity for this method.Source: §III · p. 4
  • Algorithm [15] groups patients into clusters with cluster heads that require adjustable-range nodes to reach access points.Source: §III · p. 4
  • The simulation uses 200 patients in a 200 m × 200 m area, 15 m transmission radius, Random Way Point mobility, and three-second pause times.Each 600-second scenario is averaged over 15 runs, with CBR traffic and the default IEEE 802.15 channel access.Source: §III · p. 4
  • The evaluation increases each patient's maximum Random Way Point speed up to 50 meters per minute (3 km/h) to assess mobility effects.Source: §III · p. 4

A. End-to-end delay

As patient mobility increases, PMPR has lower average end-to-end delay than the two other algorithms. Delay rises in all three scenarios as mobility increases.

A. End-to-end delay

  • PMPR has lower average end-to-end delay than the other two algorithms as patient mobility increases.The comparison is for data packets received by the sink node; the passage attributes PMPR's lower delay to sending data simultaneously over two routes.Source: A. End-to-end delay · pp. 4–5, Figure 3 · p. 5
  • End-to-end delay rises greatly in all three scenarios as mobility increases lost connections, packet resends, or route rediscovery.Source: A. End-to-end delay · p. 5

B. Packet Delivery Ratio

The proposed algorithm has a more favorable packet-delivery outcome as patient mobility and link loss increase, attributed to discovering and using reliable routes.

B. Packet Delivery Ratio

  • The proposed algorithm has a more favorable packet-delivery outcome as patient mobility and link loss increase.Figure 4 shows the percentage of packets delivered to the destination; the passage attributes the outcome to discovery and use of highly reliable routes.Source: B. Packet Delivery Ratio · p. 5, Figure 4 · p. 5

C. Energy Consumption

Energy consumption rises with patient mobility, but the proposed method consumes less energy than the other two methods. The authors attribute this difference to reduced packet loss and retransmission.

C. Energy Consumption

  • Greater patient mobility increases energy consumption by causing route losses and renewed route discovery.The resulting route-discovery process adds to energy consumption.Source: C. Energy Consumption · p. 5
  • Reduced packet loss lowers retransmissions and contributes to the proposed method’s lower energy consumption.Source: C. Energy Consumption · p. 5
  • The proposed method consumes less energy than the other two methods as patient mobility increases.Figure 5 compares energy consumption with patient mobility.Source: Figure 5 · p. 5, C. Energy Consumption · p. 5

D. Network Lifetime

Network lifetime is considered as patient mobility changes. PMPR has a longer lifetime than the two multi-hop methods, which the authors attribute to sending packets through more reliable paths.

D. Network Lifetime

  • Higher node mobility increases energy consumption, and the first network blackout occurs sooner.Source: D. Network Lifetime · p. 5
  • PMPR has a longer lifetime than the two multi-hop methods because it sends packets through more reliable paths.Figure 6 presents network lifetime versus patient mobility.Source: Figure 6 · p. 5, D. Network Lifetime · p. 5

E. Routing Overhead

PMPR has higher routing overhead than the other two methods, while the conclusion reports reduced delay and packet loss alongside increased routing overhead.

E. Routing Overhead

  • PMPR has higher routing overhead than the other two methods.The authors attribute the difference to using multiple packets during route discovery and selection; Figure 7 presents routing overhead.Source: Figure 7 · p. 6, E. Routing Overhead · p. 6

IV. CONCLUSION

  • The conclusion reports reduced end-to-end delay and packet loss, alongside increased routing-data overhead.Source: §IV · p. 6
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